Oral contraceptives, norethindrone and mestranol: effects on tissue levels of minerals

The study involved three levels of dietary zinc (deficient, marginal, and adequate) and four hormonal conditions; namely, no steriods, norethindrone, mestranol, and norethindrone plus mestranol. The steroids were incorporated into diets and fed to 11-wk-old female Sprague-Dawley rats. After 10 wk of treatment, various tissues were excised for mineral assays by atomic-absorption spectrophotometry. Both steroids, reduced weight gain. Mestranol depressed plasma zinc, tibia copper and magnesium, and liver iron, but elevated the zinc levels in liver and erythrocytes, plasma copper, liver magnesium and calcium, and iron content of tibia and heart. In general, the effect was most prominent with adequate zinc but diminished in magnitude with the reduction of zinc intake. In addition, norethindrone increased heart iron and tibia calcium. Mestranol appeared to be the main causative factor and may have induced a possible shift of minerals from one pool to another. As expected, zinc deficiency resulted in the reduction of zinc concentrations of plasma, tibia, kidney, and pancreas, and the elevation of copper, iron, magnesium, and calcium concentrations of various tissues.     

Iron status, menarche, and calcium supplementation in adolescent girls

The effects of growth, menstrual status, and calcium supplementation on iron status were studied over 4 y in 354 girls in pubertal stage 2 who were premenarcheal at baseline (x+/-SD age: 10.8+/-0.8 y). Girls were randomly assigned to placebo or treatment with 1000 mg Ca/d as calcium citrate malate. Anthropometric characteristics, bone mass, and nutritional status were measured biannually; ferritin was measured annually; and red blood cell indexes were determined at 4 y. The simultaneous effects of iron intake and menstrual status on serum ferritin, after change in lean body mass (LBM) was controlled for, were evaluated in subjects in the upper and lower quartiles of cumulative iron intake. The average maximal accumulation of LBM (386 g/mo; 95% CI: 372, 399) occurred 0.5 y before the onset of menarche. Change in LBM was a significant predictor of serum ferritin (P < 0.0001), with a negative influence on iron status (t ratio=-4.12). The 2 fitted mathematical models representing ferritin concentrations of subjects in the upper and lower quartiles of cumulative iron intake were significantly different (P < 0.018). The regression line of the ferritin concentration in menstruating girls with high iron intakes had a less negative slope than the line fit to serum ferritin concentrations in girls with low iron intakes (NS). Serum ferritin concentrations at 0, 1, 2, 3, and 4 y were not significantly different between groups. In addition, there was no significant difference between groups in any of the red blood cell indexes. In summary, growth spurt and menstrual status had adverse effects on iron stores in adolescent girls with low iron intakes (<9 mg/d), whereas long-term supplementation with calcium (total intake: approximately 1500 mg/d) did not affect iron status.     

Serum calcium, magnesium, copper and zinc and risk of cardiovascular death

OBJECTIVE: To study the association of serum calcium, magnesium, copper and zinc concentrations with cardiovascular mortality. DESIGN: A nested case-control study within a prospective population study. SUBJECTS AND METHODS: 230 men dying from cardiovascular diseases and 298 controls matched for age, place of residence, smoking and follow-up time. Mean follow-up time was 10 years. Serum calcium, magnesium, copper and zinc concentrations were determined from samples kept frozen at -20 degrees C. RESULTS: High serum copper and low serum zinc concentrations were significantly associated with an increased mortality from all cardiovascular diseases and from coronary heart disease in particular. The relative risk of coronary heart disease mortality between the highest and lowest tertiles of serum copper and zinc were 2.86 (P = 0.03) and 0.69 (P = 0.04), respectively. Adjustment for social class, serum cholesterol, body mass index, hypertension and known heart disease at baseline examination did not materially alter the results. No significant differences were observed in concentrations of serum calcium and magnesium between cases and controls. CONCLUSIONS: High serum copper and low serum zinc are associated with increased cardiovascular mortality whereas no association was found with serum calcium and magnesium and mortality risk.     

Long-term survival of 2 cases of hemochromatosis respectively homozygous for His63Asp and Cys282Tyr mutations]

A 45-year-old Greek patient was found to have a moderate iron overload (ferritin 1213 micrograms/l, serum iron 21.5 mumol/l, transferrin saturation 40%). He underwent 12 phlebotomies of 450 cc over an 8-year period and ferritin was normalized (267 micrograms/l) after the seventh. Study of the HLA-H gene in leukocyte DNA showed that the patient is homozygous for the His63Asp mutation while no modification was found at position 282. This case is compared with that of a 50-year-old Swiss male presenting a severe iron overload (ferritin 7660 micrograms/l, serum iron 36.5 mumol/l, transferrin saturation 97%). Although this patient has undergone 77 phlebotomies (450 cc each time) over a 2-year period, he continues to have a high ferritin level (2200 micrograms/l). HLA-H gene analysis showed the absence of codon 63 mutation and the presence of Cys282Tyr mutation in the homozygous state. The study of these two cases indicates that penetrance of the His63Asp mutation in the homozygous state is very low as compared to Cys282Tyr and results in moderate iron accumulation, probably without organ damage. This genotype must be looked for whenever moderate iron overload is present.     

连续光源火焰原子吸收光谱法测定氧化镍中钴铜锌铁钙镁

采用盐酸溶解样品,选择Co 240.72nm、Cu 324.75nm、Zn 213.86nm、Fe 248.33nm、Ca 422.67nm、Mg 202.58nm作为分析谱线,钴、铜、锌、铁选择3个像素点,钙、镁选择9个像素点,建立了连续光源原子吸收光谱法(CS-AAS)同时测定氧化镍中的钴、铜、锌、铁、钙、镁的方法。实验表明:在100mL测定液中加入2mL 200g/L氯化锶溶液,可消除测定介质(体积分数为2%的盐酸)对待测元素的影响;基体镍对测定的干扰可忽略。在优化的实验条件下,钴、铜、锌、铁、钙、镁的校准曲线相关系数均不低于0.999 0,且其方法检出限在0.002~0.092μg/mL之间。按照实验方法对氧化镍样品中钴、铜、锌、铁、钙、镁分别平行测定11次,钙和镁的测定值在0.1%~0.4%之间,其对应的相对标准偏差(RSD)不大于2%;钴、铜、锌、铁的测定值在0.003%~0.04%之间,其对应的相对标准偏差均小于10%。将实验方法应用于电真空镍光谱标准样品(该标样为氧化镍状态)中上述各元素的测定,结果与认定值基本一致。     

Effects of calcium supplementation and lactation on iron status

Calcium has been shown to inhibit iron absorption. The consequences of chronic calcium supplementation on iron status are unclear, however. As part of a randomized calcium-supplementation trial in lactating and nonlactating women in the postpartum period, we determined whether long-term calcium supplementation and lactation status affected iron stores as measured by serum ferritin concentrations. Subjects (95 lactating and 92 nonlactating) were enrolled at approximately 6 mo postpartum and then randomly assigned to receive either 500 mg Ca as calcium carbonate or a placebo twice daily with meals for 6 mo. Lactating women weaned their infants approximately 2 mo after enrollment (ie, approximately 8 mo postpartum). Calcium supplementation had no effect on serum ferritin concentrations. At the end of the study, geometric mean serum ferritin concentrations were 28.4 microg/L in the calcium-supplemented group and 27.5 microg/L in the placebo group (P > 0.5). Lactation status was significantly related to serum ferritin concentrations. At baseline, serum ferritin concentrations were higher in lactating women than in nonlactating women (47.7 compared with 31.5 microg/L, P < 0.001). In lactating women, serum ferritin concentrations decreased by a mean of 17 microg/L after weaning. By 12 mo postpartum, mean serum ferritin concentrations in women who were previously lactating were not significantly higher than those of nonlactating women (30.5 compared with 25.5 microg/L). These findings provide reassurance that long-term calcium supplementation does not impair iron stores. Furthermore, lactation status should be considered when assessing iron nutriture of women and determinants of iron status in populations.     

Blood vitamins, mineral elements and inflammation markers as risk factors of vascular and non-vascular disease mortality in an elderly population

BACKGROUND: The need for protecting agents against degenerative processes of the body has been proposed to be especially high in elderly people. In order to evaluate the prognostic value of various biochemical factors in ageing the associations of blood concentrations of several vitamins, mineral elements and some other suggested risk factors with vascular and non-vascular mortality were studied in an elderly population. METHODS: A large health survey with complete clinical evaluation was carried out in the City of Turku in 1982-1983. A random sample of 344 community-living elderly individuals aged 65 years or older, stratified into four age groups, was studied. During the 13 years follow-up 225 subjects had died. Calcium, magnesium, copper, ceruloplasmin, zinc, selenium, iron, ferritin, transferrin, alpha-tocopherol, retinol, folate, vitamin B12, malondialdehyde, orosomucoid and insulin levels were analysed from the blood specimens. The relations between the compounds measured and relative mortality risks during the 13-year follow-up were analysed by Cox proportional hazards model adjusting for other known risk factors. RESULTS AND CONCLUSIONS: High concentrations of serum copper, orosomucoid and insulin were associated with increased risk of vascular mortality. The relative risks within the subjects of the highest tertile of serum concentrations were 2.2 for copper, 1.8 for orosomucoid, and 1.8 for insulin when adjusted for many confounding risk factors. Low serum vitamin B12 concentrations appeared to be significantly (P = 0.01) associated with increased vascular mortality. The associations were essentially not more significant when adjusted only for age. Contrary to earlier observations concentrations of serum magnesium, selenium, alpha-tocopherol, iron and its binding proteins or plasma and erythrocyte folate were not associated with increased mortality risk when adjusted for confounding risk factors. The authors suggest that in elderly subjects these elements and compounds are at the most weak, and probably non-independent risk factors for vascular mortality.     

Zinc protoporphyrin (ZPP) in diagnosis of anemia

In iron deficiency, zinc protoporphyrin (ZPP) is produced instead of heme, and the ZPP concentration in erythrocytes increased (normal value < 2.3 micrograms ZPP/g Hb). The ZPP level and comparison with the other normally used tests in iron deficiency in the group of the patients with iron deficiency, ACD, MDS, AML, plasmocytoma was investigated. The ZPP level was determined by hematofluorometry in samples from 96 patients. Thirty five patients with iron depletion showed decreased both serum ferritin (median 5.9 ng/ml), and hemoglobin level (median 9.8 g/dl) with significantly increased ZPP level (median 8.5 micrograms/gHb). An increased level of ZPP (median 3.95 micrograms/gHb) with normal level of ferritin (median 24 ng/ml) and iron (median 50 (g/dl) in the serum of patients with ACD was determined. Measurement of ZPP level in the combination with ferritin and peripheral blood morphology allows to classify the degree of iron deficiency. The ZPP levels higher than 4.55 micrograms/gHb confirms iron deficiency in the group of anaemic patients.     

Plasma homocysteine, a risk factor for cardiovascular disease, is lowered by physiological doses of folic acid

Elevated plasma homocysteine, an independent risk factor for cardiovascular disease (CVD) can be lowered by administration of pharmacological doses of folic acid. The effect of lower doses in apparently normal subjects is currently unknown but is highly relevant to the question of food fortification. Healthy male volunteers (n = 30) participated in a chronic intervention study (26 weeks). Folic acid supplements were administered daily at doses increasing from 100 micrograms (6 weeks), to 200 micrograms (6 weeks), to 400 micrograms (14 weeks). Fasting blood samples collected before, during and 10 weeks post intervention were analysed for plasma homocysteine, serum and red-cell folate levels. Results, expressed as tertiles of baseline plasma homocysteine concentration, showed significant (p < or = 0.001) homocysteine lowering in the top (10.90 +/- 0.83 mumol/l) and middle (9.11 +/- 0.49 mumol/l) tertiles only. In the low tertile, where the mean baseline homocysteine level was 7.07 +/- 0.84 mumol/l, no significant response was observed. Of the three folic acid doses, 200 micrograms appeared to be as effective as 400 micrograms, while 100 micrograms was clearly not optimal. There is thus a minimal level of plasma homocysteine below which folic acid has no further lowering effect, probably because an optimal folate status has been reached. A dose as low as 200 micrograms/day of folic acid is effective in lowering plasma homocysteine concentrations in apparently normal subjects. Any public health programme for lowering homocysteine levels, with the goal of diminishing CVD risk, should not be based on unnecessarily high doses of folic acid.     

Effects of trace element and/or vitamin supplementation on vitamin and mineral status, free radical metabolism and immunological markers in elderly long term-hospitalized subjects. Geriatric Network MIN. VIT. AOX

A randomized double-blind trial was performed in order to assess the efficacity of differing combinations of antioxidant nutrients on biochemical parameters of vitamin and trace element status, immunological parameters and free radical metabolism in elderly long term hospitalized subjects. A total of 756 institutionalized elderly subjects were recruited in 26 nursing homes in different areas of France. Four groups were constituted, receiving daily, for 1 year, either vitamins (beta-carotene, 6 mg; vitamin C, 120 mg; and vitamin E, 15 mg), trace elements (zinc, 20 mg and selenium, 100 micrograms), trace elements associated with vitamins, or a placebo. Biochemical indicators of trace elements and vitamin status and free radical parameters were measured before and after 6 months and 1 year of supplementation. Some immunological markers were investigated initially and after 6 months of supplementation on a subsample of 134 subjects. Mean plasma levels of alpha-tocopherol, gamma-tocopherol, vitamin C, alpha-carotene, beta-carotene and copper increased significantly after 6 months of supplementation in groups receiving vitamins alone or associated with trace elements. Serum selenium concentrations were significantly increased at 6 months of supplementation, and serum zinc only after one year in the trace element groups. Serum lycopene levels were significantly decreased by trace element supplementation. A significant increase in Se-glutathione peroxidase (GPx) levels was observed in groups receiving trace elements alone or associated with vitamins. No effect was noted on superoxide dismutase (SOD) activity or TBARs production. No effect of supplementation was found for in vitro lymphocyte proliferative responses or most lymphocyte subsets, except for a significantly lower percentage of CD2 subsets observed in groups receiving mineral supplementation either alone or associated with vitamins. A significant difference in CD19 subsets was found in groups receiving trace elements. Mean IL-1 production was significantly higher after 6 months of supplementation in the vitamin groups.     

On the automaticity of ipsilateral response activation in the Simon effect

The purpose of this investigation was to establish whether plasma cholesterol and triacylglycerol(s) in copper deficiency can be increased or decreased by hepatic iron levels. Weanling male Sprague-Dawley rats were randomly divided into six dietary groups based on levels of dietary copper and iron. They were fed from weaning their respective diets for 6 wk. Forty percent of the copper-deficient rats fed a 15.7 mumol Fe/g diet died; 22% of those fed a diet containing 8.6 mumol Fe/g died; and there were no deaths in the 3.4 mumol Fe/g diet group. Rats belonging to the group fed the high-iron diet also exhibited the highest levels of liver iron, liver glutathione, and plasma cholesterol and triacylglycerol(s) compared with those fed either the adequate or low levels of dietary iron. There was a direct correlation (r = 0.82 and 0.77, respectively) between levels of cholesterol and triacylglycerol(s) in plasma and hepatic iron concentrations. These results provide strong evidence that points to a major involvement of iron in the lipemia of copper deficiency. These data may be important to those individuals who consume large quantities of fortified iron foods and supplement with iron but whose intake of copper is suboptimal.     

An evaluation of the Ektachem serum lithium method and comparison with flame emission spectrometry

We evaluated the performance of a new colorimetric method in dry chemistry for serum lithium (Li) assay using an Ektachem E500 analyser. Imprecision results were acceptable and the linearity was verified for concentrations within the range of 0.2-3.9 mmol l-1, i.e. y(measured) = 1.02x(calculated) + 0.07, r = 0.99. The Ektachem Li assay was unaffected by potassium (K), calcium (Ca) and magnesium (Mg) at all concentrations tested. Significant interference was caused by sodium (Na) and haemoglobin. Statistically and clinically significant interference was caused by high concentrations of Na (213 mmol l-1) with a bias of 0.20 mmol l-1 (p = 0.02) and by high levels of haemoglobin (280 mumol l-1) with a bias of 0.20 mmol l-1 (p = 0.01). Comparison of serum Li results from 80 patient samples assayed using the Ektachem method with those obtained using the IL943, a flame atomic emission spectrometry (FAES)-based method, gave a regression line equation: Ektachem = 0.95xFAES + 0.13, r = 0.96. The data revealed a mean difference of 0.10 mmol l-1 between the Ektachem and FAES results that was statistically significant (p = 0.01), but clinically negligible. We conclude that the Kodak method provides reliable Li serum results and represents a valid alternative to the FAES method.     

Effect of micronutrient supplementation on infection in institutionalized elderly subjects: a controlled trial

To determine the impact of a trace element and vitamin supplementation on infectious morbidity, a double-blind controlled trial was performed on 81 elderly subjects in a geriatric center during a 2-year period. Subjects were randomly assigned to one of four treatment groups, and received daily: placebo; trace elements/zinc 20 mg; selenium 100 micrograms); vitamins (vitamin C 120 mg; beta-carotene 6 mg; alpha-tocopherol 15 mg); or a combination of trace elements and vitamins at equal doses. (1) Before supplementation, low serum values in vitamin C, folate, zinc and selenium were observed in more than two thirds of the patients. (2) After 6 months of supplementation, a significant increase in vitamin and trace element serum levels was obtained in the corresponding treatment groups: a plateau was then observed for the whole study. (3) Subjects who received trace elements (zinc and selenium) alone or associated with vitamins had significantly less infectious events during the 2 years of supplementation. These results indicate that supplementation with low doses of vitamins and trace elements is able to rapidly correct corresponding deficiencies in the institutionalized elderly. Moreover, zinc and selenium reduced infectious events.     

Serum mineral changes in dithizone-induced diabetes before and after insulin treatment

In this study, diabetes was induced by intravenous injection of dithizone. In dithizonised diabetic animals, the levels of serum zinc, iron, and potassium were found to be higher than normal, while those of serum calcium and sodium were lower. Copper and magnesium levels were unchanged. After treatment with insulin, most of these serum levels approached the normal, except for serum potassium and magnesium.     

从铜铁锌酸性液中选择性萃取铜

采用Lix984萃取剂 ,对含铜铁锌酸性浸出液进行选择性萃取铜研究。结果表明 ,萃取剂浓度为 3%时 ,铜的萃取率可达到 99% ,且锌和铁共萃率低 ;萃取混合时间 >2min时 ,铜的萃取率达 96 % ,而铁和锌的萃取率 <5 % ;当相比 (O/A)为 1∶1时 ,铜的萃取效果最佳 ;随萃取值的增大 ,铜的萃取率升高 ,但为了避免萃取污物的大量产生 ,应控制萃取pH <2 .5。反萃试验结果表明 ,铜和铁的反萃率随着反萃剂浓度、反萃相比、反萃时间的增大而升高。     

Interactions among iron, calcium, phosphorus and magnesium in the nutritionally iron-deficient rat

We studied the development of nutritional iron deficiency 0, 10, 20, 30 and 40 days after the intake of a semisynthetic diet lacking iron (diet 0) and the possible interactions with calcium, phosphorus and magnesium in both control rats and rats after 40 days of iron deficiency. During this period, iron deficiency was found to produce stress in the rats, as evidenced by high levels of cortisol in the serum. High levels of parathyroid hormone (PTH) were also found. There was a considerable increase in the absorption of calcium, phosphorus and magnesium, but the phosphorus and magnesium balance decreased and that of calcium remained practically unchanged, although there was an increase in calcium urinary elimination. Despite the noticeable degree of bone demineralization, which was evident in the femur, serum levels of calcium, phosphorus and magnesium remained constant. The present study shows that severe nutritional ferropenic anaemia provokes significant alterations in the metabolism of calcium, phosphorus and magnesium. We conclude that these alterations should be taken into account in the treatment of this pathology, given its prevalence and the fact that it may exacerbate other pathologies, particularly those related to the metabolism of calcium and phosphorus.     

Phospholipase-C-independent inositol 1,4,5-trisphosphate formation in Dictyostelium cells. Activation of a plasma-membrane-bound phosphatase by receptor-stimulated Ca2+ influx

Glutathione (GSH) was measured using HPLC-electrochemical detection in bronchoalveolar lavage fluid from 28 neonates for up to 21 days after birth. GSH levels varied from 0.1-11.2 mumol l-1 (with a geometric mean concentration of 1.3 mumol l-1). GSH in epithelial lining fluid was estimated using the urea dilution method at 15.0 mumol l-1 (range 0.5-196 mumol l-1), which is significantly lower than observed in adult subjects. There was an L shaped relationship between GSH and the two markers of oxygen therapy, oxygen index and FiO2. The lowest GSH levels were associated with the group of infants with the most severe airways problems who required high oxygen.     

Development and evaluation of peptide-based prolyl oligopeptidase inhibitors--introduction of N-benzyloxycarbonyl-prolyl-3-fluoropyrrolidine as a lead in inhibitor design

Different supplementation schemes to build iron stores in female Indonesian adolescents were investigated. Subjects were 273 high-school girls allocated randomly to four treatment groups. During a 3-mo period one group received 60 mg Fe, 750 micrograms retinol, 250 micrograms folic acid, and 60 mg vitamin C per day; a second group received 60 mg Fe, 6000 micrograms retinol, 500 mg folic acid, and 60 mg vitamin C once a week; a third group received 120 mg Fe and the same amount of the other three micronutrients as the second group once a week; and a fourth group received only placebos. All subjects were dewormed and supplement allocation was double blind. Blood samples were collected at baseline, after 2 and 3 mo of supplementation, and 6 mo after the last supplement. After 2 mo of supplementation, groups supplemented weekly and daily showed similar significant improvements (P < 0.001) in hemoglobin and retinol concentrations, and supplementation for 3 instead of 2 mo did not significantly increase these two indicators. After 3 mo, the increase in ferritin was approximately equal to 27 micrograms/L in the daily and 14-15 micrograms/L in the weekly groups (P < 0.001), the latter having a final concentration of 42-45 micrograms/L. At 6 mo postsupplementation there were no significant differences among daily and weekly groups, but the ferritin concentration was still approximately equal to 10-12-micrograms/L higher (P < 0.001) than in the placebo group. The group supplemented weekly with 60 mg Fe complained less about side effects than the other supplemented groups (P < 0.05). Weekly supplementation with 60 mg Fe and 6000 micrograms retinol for 3 mo was optimal for improving the iron status of the adolescents for approximately equal to 9 mo.     

Iron-overload in patients on maintenance hemodialysis: diagnostic criteria, indications and treatment by desferrioxamine (author's transl)

33 patients with chronic renal failure were divided into two groups. Group I consisted of 8 non-dialysed patients without any clinical or biochemical sign of liver disturbance nor any iron supplementation. Group II consisted of 25 maintenance hemodialysis (MHD) patients treated from 2 to 13 years. 19 subjects had chronic B hepatitis. Total exogenous iron load parenteral iron and/or blood transfusions) was calculated. Body iron overload (hemosiderosis) was assessed by liver iron concentration (LIC) in needle biopsy specimens according to Barry's method (less than 200 microgram/100 mg dry weight) and serum ferritin levels (less than 360 ng/ml). 4 patients whose serum ferritin was increased with or without hepatic fibrosis and with or without any organ dysfunction due to hemochromatosis received i.v. infusions of desferrioxamine in doses of 2 g at each dialysis. Serum ferritin levels were correlated with LIC (p less than 0.001) and iron load (p less than 0.001). Hemosiderosis was noted in 16 MHD patients (group II) and correlated with iron load. Hemochromatosis was noted in 4 patients (group II). 4 hemodialysed patients with iron overload were treated by desferrioxamine from 6 to 18 months. During this therapy, body iron stores fell and organ dysfunction (heart failure, hepatic cytolysis, anaemia, diabetes mellitus improved. Long-term chelation therapy by desferrioxamine was effective and the chelated iron was readily removed by dialysis. These data show the importance of precise evaluation of iron stores in MHD patients.     

Surgical procedure for modifying the duodenum in cattle to measure bile flow and the diurnal variation in biliary manganese, iron, copper and zinc excretion

A surgical procedure is described for modifying the duodenum of cattle so that bile can be sampled and its rate of flow measured for long periods. In 12 steers, aged three months to three years and weighing between 50 and 650 kg, bile flow ranged from 2 to 12 ml per minute, the rate of flow increasing with bodyweight. The rate of flow expressed as ml per minute per 100 kg bodyweight decreased as bodyweight increased, the regression equation being in (ml per minute per 10 kg) = 1.65-0.0022 x where x = bodyweight (kg), r = 0.871. The mean concentrations of copper, iron, manganese and zinc in bile were 8.2, 6.2, 17.1 and 3.3 mumol per litre respectively. The concentration of iron was the least variable between the steers. The average total cholate concentration was 100 mmol per litre and total solids ranged from 5.4 to 7.2 per cent. Diurnal patterns in bile flow and trace element excretion were measured in four adult steers during a period of 38.5 hours. Although the rate of excretion of iron, zinc and copper and bile flow varied throughout the period, changes could not be associated with feeding or time of day. The concentration of manganese in bile and its excretion rate varied in a reproducible manner which may be related to feeding activity. The mean output of the four trace elements in bile from the four steers during 24 hours was, copper 37.7 mumol, iron 68.0 mumol, manganese 80.3 mumol and zinc 59.6 mumol.