A study of the genetic diversity of Mycobacterium tuberculosis isolated from patients in the eastern province of South Africa using random amplified polymorphic DNA profiling

We have compared the analytical performance and biological variability of three commercially available bone resorption assays: Pyrilinks-D, Osteomark, and CrossLaps, for the measurement of urinary free deoxypyridinoline (Dpd), cross-linked N-telopeptides of type I collagen (NTx), and linear C-telopeptides of type I collagen (CTx), respectively. The intraassay and interassay CVs for precision of the Dpd and NTx assays were < 10% for analyte concentrations greater than the second calibrator (i.e., 3 nmol/L Dpd or 30 nmol bone collagen equivalents/L NTx). The CTx assay demonstrated poor precision for analyte concentration lower than the third calibrator (i.e., 200 micrograms/L). The NTx assay exhibited nonlinear recovery for sample dilutions prepared in buffer; however, this nonlinear recovery could be corrected for sample dilutions made in urine at a low analyte concentration. Supplement recoveries of each of the three assays were within 100% +/- 10% on average. All three analytes showed stability through five freeze-thaw cycles. The mean day-to-day variations were 16% for Dpd, and 23% for both NTx and CTx. Similar diurnal rhythm was observed for all three assays on average, with the peak in the early morning and the nadir in the afternoon. Mean amplitude of the diurnal variation was 37% for Dpd and NTx, and 57% for CTx. Variations within the reference intervals for a healthy premenopausal population were 28% for Dpd, 57% for NTx, and 56% for CTx. Pyrilinks-D has demonstrated analytical precision and accuracy equal or superior to Osteomark and CrossLaps in all areas. Dpd exhibits the least biological variability day-to-day, within individuals across the diurnal cycle, and within a healthy premenopausal population.     

Whole body bone resorption in the growing pig

Our knowledge of total body bone resorption during growth is limited. The primary purpose of this study was to determine if a commercially available bone resorption assay, developed for measuring human bone resorption, could be used to measure whole body bone resorption in young, growing pigs. A secondary purpose was to evaluate if this method could detect changes in bone resorption in response to certain dental appliances which have been shown to change mandibular and maxillary growth. Five growing 4-month-old male Hanford minipigs (Sus scrofa) were housed in metabolic cages for 24 h, every other day, over a period of 1 month. Three of the animals were fitted with a mandibular protrusive orthodontic appliance. Total 24 h urines were collected in which the concentration of creatinine and collagen type I N-telopeptide crosslinks (NTx, a marker of bone resorption) were measured. The NTx immunoassay was originally developed for the analysis of human urine. Pig bone was powdered, defatted, and decalcified, and the resulting powder digested with bacterial collagenase. The digest was screened for NTx content, in the same fashion as the pig urines. Bone extract and pig urines were cross-calibrated to a standard of adolescent human urine. This allowed calculation of the daily quantity of pig bone resorbed. Daily metabolite excretion was quite variable in these growing animals; for NTx the CV was 31%, for creatinine the CV was 25%. The mean daily quantities of bone resorption ranged between 26 and 46 grams of bone which amounted to 1.2-1.7% of estimated total skeletal mass. The protrusive appliances increased bone resorption significantly during the first two weeks of the trial. In conclusion: the NTx assay can be used to measure bone resorption in pigs; the assay is sensitive enough to indicate changes in bone resorption, such as those caused by an orthodontic mandibular protrusive appliance. During growth, bone resorption varies greatly from day to day. On average, every 24 h, 1.4% of the skeletal mass is resorbed.     

Biochemical effects of calcium supplementation in postmenopausal women: influence of dietary calcium intake

We studied the biochemical effects of calcium supplementation during a 2-mo course in postmenopausal women (x +/- SD: 64 +/- 5 y of age and 14.5 +/- 6.7 y since menopause). The effects on calcium homeostasis and bone remodeling were assessed after 1 and 2 mo of daily administration of either calcium carbonate (1200 mg elemental Ca/d, n = 60) or a placebo (n = 56). The daily dietary calcium intake assessed before the beginning of calcium supplementation was 786 mg/d. We found a significant inverse relation between baseline intact parathyroid hormone (iPTH) and dietary calcium intake before supplementation (r = -0.48, P = 0.0002). A significant increase in urinary excretion of pyridinoline was observed when the dietary calcium intake was lower than the median value. Calcium supplementation resulted in a significant increase in 24-h urinary calcium (39%, P < 0.02) and a significant reduction of bone alkaline phosphatase at 2 mo and of all bone-resorption markers (hydroxyproline, pyridinoline, and deoxypyridinoline) at I and 2 mo without significant changes in 44-68 PTH fragments or iPTH concentrations. When the dietary calcium intake was low (mean +/- SD: 576 +/- 142 mg/d), calcium supplementation was responsible for a greater increase in urinary calcium excretion and a greater decrease in markers of bone turnover. The greatest variations were observed for deoxypyridinoline at 1 and 2 mo (-18.5%, P < 0.05) and for pyridinoline at 1 mo (-16.3%, P < 0.01). Two months of calcium supplementation in postmenopausal women was efficient in reducing markers of bone turnover, with a greater effect in women with a low dietary calcium intake.     

Exhaled nitric oxide is higher both at day and night in subjects with nocturnal asthma

Nitric oxide in exhaled air is thought to reflect airway inflammation. No data have been reported so far on circadian changes in NO in subjects with nocturnal asthma. To determine whether exhaled NO shows a circadian rhythm inverse to the circadian rhythm in airway obstruction in subjects with nocturnal asthma, we conducted a study involving six healthy controls, eight individuals without nocturnal asthma (4-h to 16-h variation in peak expiratory flow [PEF] <= 15%), and six individuals with nocturnal asthma (4-h to 16-h PEF variation > 15%). Smoking, use of corticosteroids, and recent respiratory infections were excluded. NO concentrations were measured at 12, 16, 20, and 24 h, and at 4, 8, and 12 h of the next day, using the single-breath method. At the same times, FEV1 and PEF were also measured. Mean NO concentrations were significantly higher in subjects with nocturnal asthma than in subjects without nocturnal asthma, and higher in both groups than in healthy controls at all time points. Mean exhaled NO levels over 24 h correlated with the 4-h to 16-h variation in PEF (r = 0.61, p < 0.01). Exhaled NO did not show a significant circadian variation in any of the three groups as assessed with cosinor analysis, in contrast to the FEV1 in both asthma groups (p < 0.05). At 4 h, mean +/- SD NO levels were higher than at 16 h in subjects with nocturnal asthma; at 50 +/- 20 ppb versus 42 +/- 15 ppb (p < 0.05); other measurements at all time points were similar. Differences in NO and FEV1 from 4 h to 16 h did not correlate with one another. We conclude that subjects with nocturnal asthma exhale NO at higher levels both at night and during the day, which may reflect more severe diurnal airway-wall inflammation. A circadian rhythm in exhaled NO was not observed. NO levels did not correspond to the circadian rhythm in airway obstruction. The small increase in NO at 4 h may indicate an aspect of inflammation, but it is not associated with increased nocturnal airway obstruction.     

Calcium supplementation and bone mineral density in adolescent girls

OBJECTIVE: To evaluate the effect of calcium supplementation on bone acquisition in adolescent white girls. DESIGN: A randomized, double-blind, placebo-controlled trial of the effect of 18 months of calcium supplementation on bone density and bone mass. SUBJECTS: Ninety-four girls with a mean age of 11.9 + 0.5 years at study entry. SETTING: University hospital in a small town. INTERVENTIONS: Calcium supplementation, 500 mg/d calcium as calcium citrate malate; controls received placebo pills. MAIN OUTCOME MEASURES: Bone mineral density and bone mineral content of the lumbar spine and total body were measured by dual-energy x-ray absorptiometry and calcium excretion from 24-hour urine specimens. RESULTS: Calcium intake from dietary sources averaged 960 mg/d for the entire study group. The supplemented group received, on average, an additional 354 mg/d of calcium. The supplemented group compared with the placebo group had greater increases of lumbar spine bone density (18.7% vs 15.8%; P = .03), lumbar spine bone mineral content (39.4% vs 34.7%; P = .06), total body bone mineral density (9.6% vs 8.3%; P = .05), and 24-hour urinary calcium excretion (90.4 vs 72.9 mg/d; P = .02), respectively. CONCLUSIONS: Increasing daily calcium intake from 80% of the recommended daily allowance to 110% via supplementation with calcium citrate malate resulted in significant increases in total body and spinal bone density in adolescent girls. The increase of 24 g of bone gain per year among the supplemented group translates to an additional 1.3% skeletal mass per year during adolescent growth, which may provide protection against future osteoporotic fracture.     

The predictive value of biochemical markers of bone turnover for bone mineral density in early postmenopausal women treated with hormone replacement or calcium supplementation

To compare the relative sensitivity and specificity of bone turnover indexes for bone loss or gain in early postmenopausal women, we performed a multicenter trial in 236 menopausal women (mean age, 51 yr), who were randomized to hormone replacement therapy (HRT) or calcium supplementation (CS; 500 mg/day) for 1 yr. Two markers of bone formation, osteocalcin (OC) and bone alkaline phosphatase (BSAP), and two markers of bone resorption, urinary N-telopeptide (NTx) and urinary free deoxypyridinoline (fDpd), as well as spine and femoral neck bone mineral density (BMD) were measured at baseline and 3, 6, and 12 months after treatment. Women receiving HRT (n = 105) showed a significant increase in spine BMD (+2.5%; P < 0.0001) and hip BMD (+1.0%; P = 0.02) compared to women receiving CS, who showed a decline at both sites (-1.1%; P < 0.01). All four markers showed time-dependent decreases in women receiving HRT (P < 0.001) and no change in women receiving CS alone. When baseline indexes of turnover were stratified by quartile, there was a significantly greater increase in BMD among those with the highest NTx, OC, and BSAP levels compared to that in those with the lowest NTx, OC, and BSAP levels (P < 0.05). The highest quartile for percent change from baseline to 6 months in fDpd, BSAP, and NTx was also associated with the greatest change in spine BMD at 1 yr. Receiver operator characteristic curves for percent change from baseline to 6 months in an individual marker to 1 yr change in BMD during HRT revealed that the percent change in NTx provided the greatest discrimination between gain and loss of BMD. When subjects receiving HRT were compared by their positive or negative skeletal response at 1 yr and their baseline turnover marker, initial NTx values were significantly higher in those that gained bone than in those that lost bone (P = 0.0002). CS women in the highest quartile for NTx at baseline had significantly greater decreases in spine BMD than subjects with the lowest NTx values (P < 0.005), although this was not true for fDpd (P < 0.20). In conclusion, for early postmenopausal women there are differential responses of biochemical markers to HRT and CS. Baseline urinary NTx and serum OC were the most sensitive predictors of change in spine BMD after 1 yr of either HRT or CS. Similarly, the percent change in NTx and OC from baseline to 6 months best predicted bone gain or loss. We conclude that markers of bone formation and resorption can be used clinically to predict future BMD in early postmenopausal women.     

Effects of alendronate on bone turnover markers in early postmenopausal women

BACKGROUND: Alendronate sodium (Fosamax, Merck, Sharp & Dohme, Whitehouse Station, NJ, USA) is an aminobisphosphonate that can inhibit osteoclast-mediated bone resorption activity to reduce bone turnover rate and improve progressive gains in bone mass. METHODS: This was a randomized, double-blind, placebo-controlled study comparing the effects on bone turnover markers between daily treatment with alendronate sodium 10 mg and placebo. Forty early postmenopausal women completed three months of treatment. The bone turnover rate was determined by measuring the biochemical markers at baseline, week 6 and at the end of the three-month treatment period. All adverse events were recorded during each follow-up visit. RESULTS: Patients receiving alendronate treatment had a significant decrease in urinary excretion of the bone resorption marker deoxypyridinoline (Dpd) as well as one of the bone formation markers, bone-specific alkaline phosphatase (AlkP-B). Patients receiving placebo tended to have increased urinary excretion of bone resorption and formation markers. At the end of three months, the mean percentage change of Dpd and AlkP-B from baseline in the group receiving 10 mg alendronate was 30.49% and 29.45% reduction, respectively. The placebo group had 2.39% and 1.52% increase, respectively. Overall, three biochemical markers (Dpd, AlkP-B and osteocalcin) differed significantly between the treatment and control groups after three months of treatment. The drug was well tolerated, without a significant increase in incidence of adverse effects such as gastrointestinal discomfort and esophageal irritation. CONCLUSIONS: Bone turnover rate decreased quickly following drug administration. The incidence of adverse effects did not differ significantly between the alendronate and placebo groups. Alendronate is, therefore, recommended as an effective nonhormonal treatment for postmenopausal osteoporosis.     

Comparison of biochemical markers of bone turnover in Paget disease treated with pamidronate and a proposed model for the relationships between measurements of the different forms of pyridinoline cross-links

We have compared the use of new markers of bone turnover in the assessment and treatment of Paget disease and made observations on the mechanisms of bone resorption. Urine hydroxyproline (Hyp) as a bone resorption marker and serum alkaline phosphatase (ALP) as a bone formation marker have traditionally been used to biochemically assess and monitor treatment of Paget disease. Hyp and total ALP were compared with total urine pyridinoline (Pyd) and deoxypyridinoline (Dpd), free urine Pyd and Dpd, urine type I collagen N-terminal cross-linked telopeptide (NTX), type I collagen C-terminal propeptide (PICP), serum osteocalcin, and bone ALP in Paget patients treated with pamidronate. Patients were divided into three biochemical severity-based treatment groups by their fasting urine hydroxyprolline excretion (HypE) levels (Le., group 1, HypE < 5.0 mumol/l of glomerular filtrate [GF]; group 2, HypE of 5.0-9.9 mumol/l of GF; group 3, HypE > 10 mumol/l of GF). Group 1 received one 60 mg intravenous infusion of pamidronate, and groups 2 and 3 received four and six 60 mg infusions at weekly intervals, respectively. Fasting serum and morning urine specimens were taken before and at 2, 6, 13, and 26 weeks after starting treatment. Baseline Z scores were used to compare separation of patient results from normal, and the difference in Z scores from baseline to 13 weeks was used to compare response to treatment. Baseline discrimination and response to treatment at all disease activity levels was greatest for NTX and was poor for osteocalcin, PICP, and C-terminal cross-linked telopeptide of type I collagen (ICTP). The other markers showed good discrimination and response at medium and high levels of disease activity. NTX, total Pyd and Dpd, free Pyd and Dpd, and ICTP are all pyridinoline cross-link-based markers, but discrimination and response by NTX was generally much greater than for the others. Determination of the mechanism of the difference between NTX and other cross-link measures is necessary for appropriate use of the markers and may also lead to a better understanding of the bone resorption process. It has been proposed that the greater sensitivity and discrimination of NTX is because it is more bone-specific than the other cross-link markers with significant amounts of free Pyd and Dpd coming from nonbone sources. We propose another model where the proportion of peptide-bound cross-links such as NTX may be increased in high bone turnover states partly due to a rate-limiting step in their degradation to free cross-links. Conditions with high bone resorption rates would have high levels of NTX that would decline rapidly when resorption rates fall to a level where the capacity to degrade NTX matches the rate of production.     

Is there a means for cost reduction in intensive care fluid therapy without a loss of quality?

The objective of this study was to examine the value of NTx, a urinary cross-linked N-telopeptides of type I collagen, as a marker of bone resorption. We assessed changes in pre- and postmenopausal bone resorption by evaluating the correlation of NTx with L2-4 bone mineral density (BMD) in a total of 1100 Japanese women, aged 19-80 years [272 premenopausal (45.2 +/- 6.2 years) and 828 postmenopausal (59.5 +/- 6.2 years)]. Postmenopausal women were divided into three groups based on the range of BMD (normal, osteopenic, and osteoporotic). Within each group, subjects were further segregated according to years since menopause (YSM). NTx values were then evaluated for each group. Our results showed that BMD was significantly decreased (P < 0.05) and NTx was significantly increased (P < 0.01) after menopause in age-matched analysis. Consistent with a previous report, NTx was inversely correlated with BMD for the entire cohort of study subjects (r = -0.299), although NTx correlated better with premenopausal than postmenopausal BMD (r = -0.240 versus r = -0.086). This may have been due to the fact that elevated values of NTx were exhibited over the entire range of BMD present in the postmenopausal women, suggesting that NTx might respond faster to the estrogen withdrawal than BMD. In all postmenopausal women, regardless of the range of BMD, the increase in NTx reached a peak within 5 YSM. After 11 YSM, however, NTx remained elevated in the osteoporotic group but it decreased in the osteopenic group, and showed no significant change in the group of postmenopausal women with normal BMD. These findings suggest that bone resorption is dramatically increased within 5 years after menopause but remains increased only in osteoporotic women.     

Quantification of biochemical markers of bone turnover by kinetic measures of bone formation and resorption in young healthy females

The quantification of biochemical markers of bone formation and resorption with kinetic measures of bone turnover is an essential step in their validation. Some biochemical markers have been validated by quantification against formation and resorption rates measured by calcium kinetics in adults with bone disease. However, none has been validated in healthy individuals who are undergoing skeletal growth and bone consolidation. Therefore, we have measured biochemical markers of bone formation (serum osteocalcin [OC], bone-specific alkaline phosphatase [BAP], and total alkaline phosphatase [ALP]) and resorption (serum tartrate resistant acid phosphatase [TRAP], urinary cross-linked N teleopeptides of type I collagen/creatinine [NTx/Cr], and hydroxyproline/creatinine [OHP/Cr]) in healthy females aged 11-32 years (n = 31) after an overnight fast to determine their relationship with bone formation (Vo+) and bone resorption (Vo-) as measured by calcium kinetics and balance. All biochemical markers were highly intercorrelated (r > 0.6, p < 0.001) as were Vo+ and Vo- (r = 0.91, p < 0.001). Highly significant correlations were present between bone formation measured by calcium kinetics (Vo+) and serum levels of bone biochemical markers (OC, r = 0.82, p = 0.001; ALP, r = 0.92, p = 0.001; and BAP, r = 0.90, p = 0.001) and between bone resorption measured by calcium kinetics (Vo-) and fasting serum levels and urine creatinine ratios of biochemical markers (TRAP, r = 0.77, p < 0.001; OHP/Cr, r = 0.79, p < 0.001; and NTx/Cr, r = 0.70, p < 0.001). Thus, biochemical markers of bone formation and resorption can be used to predict calcium kinetic rates during skeletal growth and the early years of formation of peak bone mass, ages at which strategies to build peak bone mass are important. Biochemical markers of formation and resorption are equally useful in predicting either the bone formation rate or the resorption rate.     

Effects of calcium supplementation using AAACa or milk on nocturnal bone resorption in young women

In order to study the effect of calcium supplementation on bone resorption, a randomized controlled crossover study was carried out on eight healthy 18-19 year old female volunteers using either AAACa heated oyster shell with vacuum-heated seaweed or milk. Regimen A consisted of an oral dose of 200 mg calcium in the form of AAACa. B 200 ml milk after breakfast and supper and at bedtime, and C control with no calcium supplement. Early morning fasting blood and urine sampling was carried out after 7 days of calcium supplementation. Serum calcium was higher in groups A and B than in C, and serum intact parathyroid hormone (PTH) was significantly lower in group A than in groups B and C, according to a paired t-test. Urinary excretion of crosslinked collagen degradation product, pyridinoline and deoxypyridinoline showed a similar decrease in groups A and B but not in C. The more effective suppression of PTH by AAACa than by milk may be due to its higher bioavailability and the absence of phosphate stimulating PTH secretion.     

Oestrogen-progestogen oral contraceptives and urinary calcium excretion

To examine the effects of age and use of oestrogen-progestogen oral contraceptive agents (OCA) on urinary calcium excretion, 24 h urine collections were obtained from 525 women aged 16-69 years during a health survey, and measurements made of the amounts of calcium, creatinine, sodium, potassium and magnesium excreted. Younger women using OCA excreted more potassium and creatinine but less calcium, and less calcium and magnesium relative to creatinine, than corresponding controls using no OCA. Older women excreted less creatine, but significantly greater amounts of calcium, sodium, potassium and magnesium relative to creatinine than younger women. It is postulated that the diminished urinary calcium excretion observed in women using OCA resulted from suppression of bone resorption by oestrogens in OCA.     

Prevention of bone loss induced by thyroxine suppressive therapy in postmenopausal women: the effect of calcium and calcitonin

Although controversies exist on the possible adverse effect of T4 on bone mass, most studies reported bone loss in estrogen-deprived postmenopausal women taking suppressive doses of T4. We prospectively studied 46 postmenopausal women with carcinoma of thyroid for 2 yr to evaluate the rate of bone loss and assess whether calcium supplementation with or without intranasal calcitonin was able to decrease the rate of bone loss. All patients were receiving a stable dose of L-T4 (170 +/- 60 micrograms/day or 3.0 +/- 1.4 micrograms/kg.day) for more than 1 yr. All had TSH levels of 0.03 mIU/L or less and an elevated free T4 (FT4) index, but normal T3 levels. The calcium intake was low and averaged 507 +/- 384 g/day as assessed by dietary recall. The subjects were randomized into three groups: 1) intranasal calcitonin (200 IU daily) for 5 days/week plus 1000 mg calcium daily, 2) calcium alone, or 3) placebo. Total body and regional bone mineral density were measured by a dual energy x-ray absorptiometry bone densitometer at 6-month intervals. The results showed that both groups 1 and 2 had stable bone mass, whereas patients in groups 3 showed significant bone loss at the end of 2 yr (lumbar spine, 5.0%, hip, 6.7%, trochanter, 4.7%; Ward's triangle, 8.8%; P < 0.05), with bone mineral densities at all four regions lower than those in the other two groups (P < 0.05). There were no differences between groups 1 and 2. All three groups had elevated osteocalcin levels compared with age-matched reference controls. At 1 yr, the osteocalcin level decreased in groups 1 and 2, but remained significantly raised in group 3. No significant changes were detected in the bone-specific alkaline phosphatase levels. Urinary hydroxyproline excretion increased in group 3 at the end of 2 yr, but remained the same in groups 1 and 2. In conclusion, T4-suppressive therapy was associated with bone loss in postmenopausal women, which could be prevented by either calcium supplementation or intranasal calcitonin, although the latter did not provide additional benefit compared to calcium alone. However, careful titration of T4 dosage to maintain biochemical euthyroidism is a better way to avoid the adverse effect of T4 on bone.     

Seasonal variations in vitamin D status and calcium absorption do not influence bone turnover in young women

OBJECTIVE: To evaluate the effect of seasonal variations in UV B-exposure on calcium absorption and bone turnover in young women with the overall goal to assess the potential benefit of a vitamin D supplementation during wintertime. DESIGN: Cross-sectional study. SETTING: Area of Bonn, Germany (51 degrees N). SUBJECTS: Thirty-eight women (24.5+/-0.5 y) studied in winter and 38 females of the same age (24.7+/-0.4 y) studied in summer. RESULTS: As estimated by a 4 d food record, both groups had similar dietary calcium and phosphorus intakes (> 1200 mg/d, respectively) covering actual recommendations. Significant reductions in serum concentrations of 25-hydroxyvitamin D (25OHD) and calcitriol, fractional calcium absorption (Fc220, measured by means of a stable strontium test), 24h urinary calcium and 24h urinary phosphorus excretion were observed during wintertime. 25OHD but not calcitriol was correlated with Fc220 values and with 24h urinary phosphorus excretion. Moreover, Fc220 was related to 24 h urinary calcium excretion. Fasting 2 h-urinary deoxypyridinoline concentrations (biomarker of bone resorption) and serum levels of carboxyterminal propeptide of type I procollagen (biomarker of bone formation) showed no differences between summer and winter. CONCLUSIONS: Our data indicate a decrease in intestinal calcium and phosphorus absorption during wintertime, most likely because of a reduction in serum 25OHD levels. Since bone turnover was not affected by the seasonal differences in mineral metabolism, there is no objective for young women with high calcium intake to supplement vitamin D during wintertime.     

The measurement of urinary amino-terminal telopeptides of type I collagen to monitor bone resorption in patients with primary hyperparathyroidism

This study was carried out in order to evaluate clinical usefulness of cross-linked N-telopeptides (NTx) of type I collagen determination, in patients with primary hyperparathyroidism. Twenty-six consecutive patients (6 males and 20 females, aged 56.3 +/- 15.0, SD, yrs) with primary hyperparathyroidism were studied in basal conditions and, ten of them, after surgical cure of the disease. Cross-linked collagen peptides were measured by enzyme-linked immunosorbent assay and conventional markers of bone turnover according to standard procedures. Bone densitometry at the lumbar spine and proximal femur was performed using dual-energy X-ray absorptiometry. Bone mineral density, was also assessed at the junction of the distal and middle third of the radius and at the ultradistal radius of the non-dominant arm by a dual photon densitometer. Mean urinary NTx values (194.2 +/- 121.9 pmoles bone collagen equivalents/mumoles creatinine) were significantly higher (p < 0.001) in respect to those found in normal subjects. The mean increase of Z score values of both serum tartrate resistant acid phosphatase activity (1.4 +/- 1.8) and the fasting hydroxyproline/creatinine ratio (1.45 +/- 2.0) was significantly lower (p < 0.02) in respect to that of NTx Z score values (3.3 +/- 3.3); the latter values were not significantly different than mean Z score values of serum osteocalcin (4.0 +/- 3.9), serum alkaline phosphatase activity (2.6 +/- 2.6) and urinary calcium/creatinine ratio (3.2 +/- 3.3). We found a significant inverse correlation between NTx values and both lumbar spine (p < 0.01) and ultradistal radius bone mineral density (p < 0.05); a modest inverse correlation was also observed between serum tartrate resistant acid phosphatase activity and lumbar spine bone mineral density (p < 0.04). Following successful adenoma removal, the percentage decrease of both NTx and hydroxyproline was similar in patients with increased bone turnover rate; major discrepancies were observed in patients with normal values of NTx, the telopeptide reduction being greater than that of hydroxyproline. Finally, in a hypercalcemic patient with metastatic parathyroid cancer, telopeptide excretion was shown to be more sensitive in respect to urinary hydroxyproline when evaluating the effects of antiresorptive therapy. Our results seem to indicate that amongst the markers with good sensitivity, NTx is the only one that is inversely related with bone mineral density at two different skeletal sites. This assay should therefore have a place in both the initial screening and medical follow-up of patients with this glandular disorder; in fact, in both situations an increased urinary excretion of this marker should warn about the possibility of hidden bone loss.     

Therapeutic efficacy of 1alpha,25-dihydroxyvitamin D3 and calcium in osteopenic ovariectomized rats: evidence for a direct anabolic effect of 1alpha,25-dihydroxyvitamin D3 on bone

It is an important question for clinical therapy of osteoporosis with vitamin D metabolites whether these compounds exert their beneficial effects on the skeleton indirectly through an increase in intestinal calcium absorption or whether there is also a major direct component of action on bone. In this study, female 6-month-old Fischer rats were either ovariectomized (OVX) or sham operated. One month before surgery, all rats were placed on a diet containing 0.25% calcium and were kept on this diet throughout the study. Beginning 3 months post-OVX, groups of OVX rats orally received vehicle, a calcium supplement, low dose (0.025 microg/kg x day) or high dose (0.1 microg/kg x day) 1alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3], or combinations of low and high dose 1,25-(OH)2D3 with the calcium supplement. By 3 months postsurgery, pretreatment OVX controls had lost 74% and 37% of tibial and vertebral cancellous bone, respectively. Two-way factorial ANOVA showed that a 3-month treatment of osteopenic OVX rats with 1,25-(OH)2D3 dose dependently increased vertebral and tibial cancellous bone mass (P < 0.001 and P = 0.021, respectively) and trabecular width (P < 0.001). Furthermore, 1,25-(OH)2D3 increased serum calcium (P = 0.028) and urinary calcium excretion (P < 0.001) and reduced serum PTH levels (P < 0.001), osteoclast numbers (P < 0.001), and urinary collagen cross-links excretion (P < 0.001). Calcium supplementation alone was without therapeutic effect, and there was no significant two-way interaction between the individual treatment effects of 1,25-(OH)2D3 and calcium on bone mass. These data indicate that the anabolic effects of 1,25-(OH)2D3 in osteopenic OVX rats are mediated through a direct activity on bone.     

Diagnostic validity of bone metabolic markers for bone metastasis

We measured bone resorption markers in tumor patients with and without bone metastases and evaluated the diagnostic validity of these biochemical parameters in the diagnosis of neoplastic bone involvement. On the basis of radiography and bone scintigraphy findings, subjects were divided into 3 groups, 83 patients without bone metastases (META(-)), 22 patients with 1 or 2 bone metastases (META(+)) and 22 patients with more than 3 bone metastases (META(++)). Among the biochemical markers, urinary pyridinoline (PYR), circulating C-terminal telopeptide of type I collagen (ICTP) and urinary N-terminal telopeptide of type I collagen (NTx) were especially sensitive and specific and increased significantly not only in META(++) but also even in META(+). The efficacy of several bone metabolic markers in differentiating between patients with and without bone metastases was evaluated by receiver-operating characteristic (ROC) analysis, and PYR, ICTP and NTx were proved to have high diagnostic validity (area under the ROC curve; 0.75 for PYR, 0.77 for ICTP and 0.77 for NTx). Furthermore, their odds ratios showed significantly high values for both META(+) and META(++)(to META(++); 7.91 for PYR, 5.33 for ICTP and 5.70 for NTx). On the other hand, urinary deoxypyridinoline (DPYR) and serum total alkaline phosphatase (ALP) showed relatively low sensitivities, the odds ratio of ALP in particular being insignificant. In conclusion, several bone metabolic markers were proved to be useful in the diagnosis of bone metastases in patients with malignancies, particularly PYR, ICTP and NTx had rather high diagnostic validities among all markers examined in this study.     

Bone hyperresorption is prevalent in chronically critically ill patients

STUDY OBJECTIVE: Chronically critically ill (CCI) patients are primarily elderly people who have survived a life-threatening episode of sepsis but remain profoundly debilitated and ventilator dependent. The objective of this study was to determine the prevalence of bone hyperresorption and parathyroid hormone (PTH)-vitamin D axis abnormalities in these patients. DESIGN: Prevalence survey. SETTING: Respiratory care step-down unit (RCU) at a tertiary care teaching hospital. PATIENTS: Forty-nine ventilator-dependent CCI patients transferred from ICUs within the same institution. INTERVENTION: None. MEASUREMENTS AND RESULTS: N-telopeptide (NTx) levels in 24-h urine collections and serum intact PTH, 25-vitamin D, and 1,25-vitamin D levels were measured within 48 h of RCU admission. Patients were hospitalized a median of 30 days before RCU admission. Four patients (9%) had normal NTx and PTH levels. Forty-five patients (92%) had elevated urine NTx levels consistent with bone hyperresorption. Nineteen patients (42% of total patients) had elevated PTH levels consistent with predominant vitamin D deficiency, 4 patients (9%) had suppressed PTH levels consistent with predominant hyperresorption from immobilization, and 22 patients (49%) had normal PTH levels consistent with an overlap of both vitamin D deficiency and immobilization. There were no differences in vitamin D metabolites among these groups. CONCLUSIONS: CCI patients have a high prevalence of bone hyperresorption in which PTH levels may clarify the cause. Further studies will determine the efficacy and cost-effectiveness of routine NTx and PTH screening in these patients and the role of vitamin D and antiresorptive therapies.     

Effects of growth hormone (GH) replacement on bone metabolism and mineral density in adult onset of GH deficiency: results of a double-blind placebo-controlled study with open follow-up

It is known that GH stimulates bone turnover and that GH-deficient adults have a lower bone mass than healthy controls. In order to evaluate the influences of GH replacement therapy on markers of bone turnover and on bone mineral density (BMD) in patients with adult onset GH deficiency, a double-blind placebo-controlled study of treatment with recombinant human GH (rhGH; mean dose 2.4 IU daily) in 20 patients for 6 months and an extended open study of 6 to 12 months were conducted. Eighteen patients, fourteen men and four women, with a mean age of 44 years with adult onset GH deficiency were evaluated in the study. Compared with placebo, after 6 months serum calcium (2.39 +/- 0.02 vs 2.32 +/- 0.02 mmol/l, P = 0.037) and phosphate (0.97 +/- 0.06 vs 0.75 +/- 0.05 mmol/l, P = 0.011) increased and the index of phosphate excretion (0.03 +/- 0.03 vs 0.19 +/- 0.02, P < 0.001) decreased significantly, and there was a significant increase in the markers of bone formation (osteocalcin, 64.8 +/- 11.8 vs 17.4 +/- 1.8 ng/ml, P < 0.001; procollagen type I carboxyterminal propeptide (PICP), 195.3 +/- 26.4 vs 124.0 +/- 15.5 ng/ml, P = 0.026) as well as those of bone resorption (type I collagen carboxyterminal telopeptide (ICTP), 8.9 +/- 1.2 vs 3.3 +/- 0.5 ng/ml, P < 0.001; urinary hydroxyproline, 0.035 +/- 0.006 vs 0.018 +/- 0.002 mg/100 ml glomerular filtration rate, P = 0.009). BMD did not change during this period of time. IGF-I was significantly higher in treated patients (306 +/- 45.3 vs 88.7 +/- 22.5 ng/ml, P < 0.001). An analysis of the data compiled from 18 patients treated with rhGH for 12 months revealed similar significant increases in serum calcium and phosphate, and the markers of bone turnover (osteocalcin, PICP, ICTP, urinary hydroxyproline). Dual energy x-ray absorptiometry (DXA)-measured BMD in the lumbar spine (1.194 +/- 0.058 vs 1.133 +/- 0.046 g/cm2, P = 0.015), femoral neck (1.009 +/- 0.051 vs 0.936 +/- 0.034 g/cm2, P = 0.004), Ward's triangle (0.881 +/- 0.055 vs 0.816 +/- 0.04 g/cm2, P = 0.019) and the trochanteric region (0.869 +/- 0.046 vs 0.801 +/- 0.033 g/cm2, P = 0.005) increased significantly linearly (compared with the individual baseline values). At 12 months, BMD in patients with low bone mass (T-score < -1.0 S.D.) increased more than in those with normal bone mass (lumbar spine 11.5 vs 2.1%, P = 0.030, and femoral neck 9.7 vs 4.2%, P = 0.055). IGF-I increased significantly in all treated patients. In conclusion, treatment of GH-deficient adults with rhGH increases bone turnover for at least 12 months. BMD in the lumbar spine and the proximal femur increases continuously in this time (open study) and the benefit is greater in patients with low bone mass. Therefore, GH-deficient patients exhibiting osteopenia or osteoporosis should be considered candidates for GH supplementation. However, long-term studies are needed to establish that the positive effects on BMD are persistent and are associated with a reduction in fracture risk.     

A randomized, placebo-controlled trial of calcium supplementation for decreased bone density in corticosteroid-using patients with inflammatory bowel disease: a pilot study

BACKGROUND: Patients with inflammatory bowel disease (IBD) have a high prevalence of osteoporosis. A number of studies have found that corticosteroid use is associated with the development of osteoporosis in these patients. Calcium supplementation may be of benefit in corticosteroid-induced osteoporosis and calcium may be a nutrient that patients with IBD lack. AIM: To test the benefit of calcium supplementation on bone density in a pilot study over a 1-year period, in a group of corticosteroid-using patients with IBD, in a randomized, double-blind, placebo-controlled treatment study. METHODS: Corticosteroid-using patients with IBD including males over the age of 18 years and premenopausal females, were randomized to receive either calcium carbonate 1000 mg plus vitamin D 250 IU (Oscal) or an identically matched placebo. Dual energy X-ray absorptiometry measurements of bone density were obtained at entry and at 1 year. At entry, and every 3 months thereafter, serum was collected for the measurement of haemoglobin, biochemistry and bone hormones. Simultaneously a 24-h urine collection was analysed for calcium excretion and creatinine clearance, and a 4-day food record was collected to document dietary calcium and vitamin D ingestion. RESULTS: We found a high prevalence of moderately severe decreased bone density in corticosteroid-using patients with IBD. The dose of prednisone in the year prior to study entry was inversely correlated with bone density at the hip (R = -0.67, P = 0.004). At study entry serum osteocalcin was inversely correlated with corticosteroid dose in the year prior to the study (R = -0.64, P = 0.02) and at study end, directly correlated with the percentage change in spine bone density (R = 0.59, P = 0.01). The dietary calcium intake of these patients was close to the current RDA (recommended daily intake) for premenopausal, post-adolescent adults. Calcium supplementation with small extra doses of vitamin D conferred no obvious benefit to bone density at the end of 1 year. There was no correlation between oral calcium ingestion and bone mass measurements. Both the treatment and placebo groups' bone density remained relatively stable at 1 year, suggesting that bone loss in corticosteroid-using patients may peak early into the use of the corticosteroids. CONCLUSIONS: Calcium supplementation (1000 mg/day) conferred no significant benefit to bone density at 1 year in patients with corticosteroid-using IBD patients with osteoporosis. Future investigations should explore other therapeutic avenues that may have greater effects on increasing bone density in patients who already have considerable osteoporosis.