Reliability of copper reduction methods for quantitation of glucosuria

In the present study we evaluated the reliability of the "2-drop" Clinitest method in determining the 24-h glucose spill of a diabetic patient. The urine glucose content over the 33 day study period was measured with a Beckman glucose analyzer that employed a glucose oxidase method. There was no statistical difference between the glucose content determined by the two methods. There was a mean error of +4.4 +/- 3.6% between the values obtained with the "2-drop" method and values obtained with glucose analyzer. The mean coefficient of variation for determining the glucose content of urine with the "2 drop" method was 19%. In a group of 10 normal volunteers we found that there was a falsely elevated glucose value in urines with osmolality of less than 295 mosm/kg when the "5-drop" method was used. The "2-drop" Clinitest and the Beckman analyzer could accurately determine glucose concentration even in these dilute urines. The "2-drop" Clinitest method is a useful and reasonably reliable method for evaluationg 24-h glucosuria.     

Hormonal control of water and sodium in plasma and urine of camels during dehydration and rehydration

Eight dromedary camels were studied for 24 days under control conditions (3 days), and during water deprivation (14 days) and rehydration (7 days) in Tadla (Morocco), during the summer. During dehydration, food intake gradually fell and was zero on the last day and animals lost about 30% of their body weight. However, most of this reduction in weight was attributed to water loss, since body weight of the animals returned to control values following rehydration. Dehydration was associated with a decrease in plasma volume (-42 +/- 3%) and a concomitant rise in plasma Na concentration (from 154 +/- 2 to 191 +/- 3 mM). These changes were accompanied by increased plasma arginine-vasopressin (from 0.2 +/- 0.1 to 5.7 +/- 2.2 pg ml-1) and plasma renin activity (from 1.2 +/- 0.2 to 20.0 +/- 5.2 ng Al ml-1 hr-1), without significantly changed plasma concentrations of aldosterone and atrial natriuretic peptide. Dehydration was associated with increased urine osmolality (from 952 +/- 515 to 1963 +/- 498 mosm kg-1 H2O), reduced urine production (from 4565 +/- 2230 to 817 +/- 178 ml day-1), and increased Na excretion. Most of these parameters returned to control values during initial rehydration, except for plasma renin activity, which remained elevated for 7 days, and diuresis, which rose to 12773 +/- 6707 ml day-1 on Day 7 of rehydration.     

Responses of reindeer to water loading, water restriction and ADH

Two female reindeer were hydrated by administration of (10% of b.wt.) water into the rumen. The diuretic response was very fast and strong but the urea and electrolyte excretion were little affected. Dehydration was carried out by not giving the reindeer water for 48 h. This water deprivation caused a loss of up to 20% of their body weight. The urine osmolality did not exceed 840 mosm/kg H2O, although the plasma osmolality rose from 300 to 346 and 368 mosm/kg H2O respectively. The plasma and urine urea concentrations were elevated during dehydration, while the urine urea excretion did not increase. Urine sodium concentration did not increase. When the urine flow rate, after two days of water deprivation, decreased to half of the original, the urine Na+ concentrations, instead of increasing, went down to half of the original. So did the potassium excretion. When ADH was injected intravenously into hydrated animals a dose of 30 mU of ADH was needed to induce antidiuresis or increased excretion of potassium. The resistance to ADH and the low relative thickness of the medulla confirm the limited capacity of reindeer kidney to concentrate urine or to excrete a solute load. On the other hand, reindeer is able rapidly to excrete surplus water without affecting the electrolyte or nitrogen balance.     

Organisation of the bph gene cluster of transposon Tn4371, encoding enzymes for the degradation of biphenyl and 4-chlorobiphenyl compounds

We have isolated beta-trace protein from cerebrospinal fluid, serum, plasma, and urine samples of normal volunteers and sera and hemofiltrate of patients with chronic renal failure. Blood-derived and urinary beta-trace have significantly higher molecular weights than their cerebrospinal fluid counterpart, the amino acid sequences being identical. Oligosaccharide structural analysis revealed these molecular weight differences to be due to different N-glycosylation. beta-Trace from hemofiltrate and urine has larger sugar chains and concurrently significantly higher sialylation than cerebrospinal fluid-beta-trace which bears truncated "brain-type" oligosaccharide chains (published previously). beta-Trace concentrations were about 40 ng/ml for normal sera and plasma. 2000-6000 ng/ml were measured in sera of dialysis patients whereas in normal human cerebrospinal fluid, beta-trace concentration was about 8000 ng/ml. A reduced amount of 900 ng/ml was found in a single case of hydrocephalus cerebri. The sialylated glycoforms of beta-trace detected in the blood are presumably derived from resorbed cerebrospinal fluid protein whereas beta-TP-molecules bearing asialo-oligosaccharides are absent due to their hepatic clearance. The residual, sialylated beta-TP-species are probably eliminated from the blood via the kidney. This physiological clearance mechanism for the sialylated glycoforms is disturbed in hemodialysis patients resulting in about 100-fold elevated serum concentrations. These results let us suggest beta-trace may become a useful novel diagnostic protein in renal diseases.     

Limb salvage and survival rates among elderly patients with advanced limb ischemia

Beta-Thalassemia hemoglobin E (beta-thal/Hb E) is the commonest form of hemoglobinopathy in Thailand. Shortened red cell life span, rapid iron turnover and tissue deposition of excess iron are major factors responsible for functional and physiological abnormalities found in various forms of thalassemia. Increased deposition of iron had been found in renal parenchyma of thalassemic patients, but no systematic study of the effect of the deposits on renal functions has been available. The purpose of this study is to describe the functional abnormalities of the kidney in patients with beta-thal/Hb E and provide evidence that increased oxidative stress might be one of the factors responsible for the damage. Urine and serum samples from 95 patients with beta-thal/Hb E were studied comparing with 27 age-matched healthy controls. No difference in the creatinine clearance was observed. beta-thal/Hb E patients excreted significantly more urinary protein (0.8+/-0.5 vs. 0.3+/-0.1 g/day, p < 0.001). Aminoaciduria was found in 16 % of the patients. Analysis of urinary protein by SDS-PAGE electrophoresis and silver staining revealed abnormal pattern of protein with increased small molecular weight (<45 kD) bands. Morning urine analysis showed significant lower urine osmolality (578.3+/-164.6 vs. 762.4+/-169.9 mosm/kg, p < 0.001) in patients. Patients excreted more NAG (N-acetyl beta-D-glucosaminidase, 26.3+/-41.3 vs. 8.4+/-3.9 U/g Cr, p < 0.0001) and beta2-microglobulin, 124.3+/-167 vs. 71+/-65.5 microg/g Cr, p = 0.001. Plasma and urine MDA (malonyldialdehyde) levels were both raised (p < 0.0001). Nine patients were selected for renal acidification study. All were found to be normal, but showed poor response to DDAVP challenge (urine osmolality 533+/-71). This is the first report of renal tubular defects found associated with beta-thal/Hb E disease. The mechanism leading to the damage is not known but it might be related to increased oxidative stress secondary to tissue deposition of iron, as indicated by the raised levels of serum and urine MDA. It is not known whether these functional defects would have any long-term effects on the patients. Further studies are warranted and means of prevention of these defects should urgently be sought.     

Minimum urine flow rate during water deprivation: importance of the nonurea versus total osmolality in the inner medulla

Antidiuretic hormone leads to an increase in the permeability for water and urea in the inner medullary collecting duct. Hence, urea may not be an "effective" osmole in the inner medulla during maximal renal water conservation. Accordingly, the purpose of this study was to evaluate whether differences in the rate of urea excretion would influence maximum renal water conservation in humans. In water-deprived rats, the concentration of urea and total osmolality were somewhat higher in the urine exiting the inner medullary collecting duct than in interstitial fluid obtained from the entire papillary tip. Nevertheless, the "nonurea" (total osmolality minus urea in millimolar terms) osmolality was virtually identical in both locations. Chronically fasted human subjects that were water-deprived for 16 h had a lower rate of urea excretion (71 +/- 7 versus 225 +/- 14 mumol/min) and a somewhat lower urine osmolality (745 +/- 53 versus 918 +/- 20 mosmol/kg H2O). Nevertheless, they had identical urine flow rates (0.5 +/- 0.01 and 0.5 +/- 0.02 ml/min, respectively), and their nonurea osmolality also was similar (587 +/- 25 and 475 +/- 14 mosmol/kg H2O, respectively) to the water-deprived normal subjects. The composition of their urine differed in that the principal nonurea osmoles became NH4+ and beta-hydroxybutyrate rather than Na and C1. During water deprivation in normal subjects, the ingestion of urea caused a twofold rise in urine flow rate, a fall in the nonurea osmolality, and a rise in the rate of excretion of nonurea osmoles. The nonurea osmolality of the urine, and presumably the medullary interstitial fluid as well, was inversely related to the urea excretion rate. In chronic fasting, the nature, but not the quantity, of nonurea osmoles changed. The similar minimum urine volume was predictable from an analysis based on nonurea osmole considerations.     

Methohexital impairs osmoregulation. Studies in conscious and anesthetized volume-expanded dogs

BACKGROUND: Anesthetic agents influence central regulations. This study investigated the effects of methohexital anesthesia on renal and hormonal responses to acute sodium and water loading in dogs in the absence of surgical stress. METHODS: Fourteen experiments (two in each dog) were performed in seven well-trained, chronically tracheotomized beagle dogs kept in highly standardized environmental and dietary conditions (2.5 mmol sodium and 91 ml water/kg body weight daily). Experiments lasted 3 h, while the dogs were conscious (7 experiments) or, after 1 h control, while they were anesthetized (7 experiments) with methohexital (initial dose 6.6 mg/kg body weight and maintenance infusion 0.34 mg.min-1.kg-1 body weight) over a period of 2 h. In both experiments, extracellular volume expansion was performed by intravenous infusion of a balanced isoosmolar electrolyte solution (0.5 ml.min-1.kg-1 body weight). Normal arterial blood gases were maintained by controlled mechanical ventilation. In another five dogs the same protocol was used, and vasopressin (0.05 mU.min-1.kg-1 body weight) was infused intravenously during methohexital anesthesia. RESULTS: Values are given as means. During methohexital anesthesia, mean arterial pressure decreased from 108 to 101 mmHg, and heart rate increased from 95 to 146 beats/min. Renal sodium excretion decreased; urine volume increased; and urine osmolarity decreased from 233 to 155 mosm/l, whereas plasma osmolarity increased from 301 to 312 mosm/l because of an increase in plasma sodium concentration from 148 to 154 mmol/l. Plasma renin activity, plasma aldosterone concentration, plasma atrial natriuretic peptide, and plasma antidiuretic hormone concentrations (range 1.8-2.8 pg/ml) did not change in either protocol. In the presence of exogenous vasopressin (antidiuretic hormone 3.3 pg/ml), water diuresis did not occur, and neither plasma osmolarity nor the plasma concentration of sodium changed. CONCLUSIONS: Methohexital may impair osmoregulation by inhibiting adequate pituitary antidiuretic hormone release in response to an osmotic challenge.     

Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) enhance lipopolysaccharide binding to neutrophils via CD14

BACKGROUND: Microalbuminuria is an early marker of prognostic significance in diabetic renal disease. However, testing for microalbuminuria in a timed sample of urine using the double antibody radioimmunoassay (RIA) method is cumbersome and requires special laboratory facilities. Recently, a test strip for microalbuminuria, the Micral Test was available and we evaluated the performance of this test strip as a screening method for detection of microalbuminuria. METHODS: One hundred consecutive diabetic patients who were tested to be dipstick-negative (Albustix) for proteinuria were enrolled for the study. Micral Tests were performed on a paired first morning and random urine specimen from the same patient and the results compared with a timed 24-hour urine measurement of urine albumin excretion using the RIA method. RESULTS: Eighteen specimens were tested positive by the RIA method with a urinary albumin range of 32-177 mg/24 hours. With the Micral Test, the following sensitivity, specificity, positive and negative predictive values were obtained: 66.7%. 97.6%, 85.7% and 93.0% for the first morning urine specimens, and 77.8%, 91.5%, 66.7% and 94.9% for the random urine specimens. CONCLUSIONS: These results suggest that Micral Test with either the first morning or random urine specimen offers a simple, reliable, rapid and convenient method for screening of microalbuminuria in the diabetic patient.     

Free-water clearance and the early recognition of acute renal insufficiency after cardiopulmonary bypass

The predictive value of free-water clearance measurements for the early recognition of acute renal insufficiency was evaluated in 59 patients immediately following cardiopulmonary bypass. Blood urea nitrogen and serum creatinine measurements were taken before and after operation. Intraoperatively, immediately after completion of bypass, urine and serum samples were obtained for osmolality. Duration of bypass, urine output, degree of hemolysis, and quality of perfusion were recorded. Fifty-four patients developed no signs of renal insufficiency following bypass, and all had free-water clearance values equal to or less than -20 ml per hour. Five patients who had free-water clearance values equal to greater than -8 ml per hour developed manifestations of an acute renal insufficiency state. There were no false-negative or false-positive determinations. Consequently, free-water clearance measurements appear to be a reliable indicator of those patients who will develop renal insufficiency following cardiopulmonary bypass. Early recognition provides an opportunity immediately after operation for initiating treatment consisting of administration of diuretics, potassium restriction, and oliguric fluid regimens.     

Low dosage dopamine improves kidney function: current status of knowledge and evaluation of a controversial topic

The ability of low dose dopamine (1-3 micrograms x kg-1 x min-1) to cause selective renal vasodilation, to increase glomerular filtration rate, urine output, and natriuresis, is intuitively considered favourable. Dopamine, therefore, continues to be used in critically ill patients to preserve or improve renal function. Despite its application in a wide variety of disease states and in patients at risk of acute renal failure or with already decreased renal function, there is no conclusive evidence that "renal doses" of dopamine prevented acute renal failure or had any positive effect on patient outcome although it increased urine output and natriuresis consistently. Data from many clinical studies, however, are difficult to interpret due to small numbers of patients, the absence of control groups, the inability to exclude changes in cardiac output or to separate a diuretic effect of dopamine in the tubulus system from specific increases of glomerular filtration rate, and because of the variability of methods to determine renal performance (i.e. creatinine clearance, urine output, natriuresis, fractional excretion of sodium). Moreover, the routine use of dopamine is not innovous, since it may worsen gut ischaemia and suppress certain hormonal systems. Those who believe in the clinical benefits of "renal dose" dopamine argue that, even in the absence of an improvement in renal function, the maintenance of urine output could be useful in patients unresponsive to diuretics. Again, the clinical benefit of this diuretic action still needs to be shown. In conclusion, there is little justification for the routine administration of low-dose dopamine in patients at risk of renal failure. Large controlled clinical studies are urgently needed to determine whether dopamine improves renal function or prevents acute renal failure in patients at risk.     

热处理工艺对海洋工程用高强度耐低温H型钢组织及性能影响

摘要：以热轧耐低温H型钢为研究对象,采用光学显微镜、扫描电镜、透射电镜分析和力学性能测试等手段,研究了完全淬火和亚温淬火对试验钢微观组织和力学性能的演变规律。结果表明,试验型钢经780℃亚温淬火+600℃回火处理后,形成回火索氏体+铁素体的网状组织;试验型钢900℃淬火+600℃回火处理后,转变得到具有马氏体位向的回火索氏体,碳化物分布更加细小均匀,位错密度下降。2种热处理工艺制备H型钢综合力学性能优良,屈服强度均达到500MPa以上,900℃淬火+600℃回火处理后钢的屈服强度和抗拉强度更高。-40℃低温冲击韧性比热轧状态下出现大幅度提高,随着淬火温度升高冲击功更加稳定。     

Physiopathology of proteinuria and laboratory diagnostic strategy based on single protein analysis

A quantification of proteins of different molecular size has been shown to be useful in characterizing the mechanism and medical causes of proteinuria. By analyzing urine albumin, alpha1-microglobulin, immunoglobulin G and alpha2-macroglobulin together with total protein, prerenal, glomerular, tubular and postrenal causes of proteinuria can be detected and differentiated by their specific urine protein patterns. Using automated turbidimetric procedures, prerenal proteinurias are characterized by an albumin/total protein ratio below 0.4. Tubulo-interstitial diseases which are negative in the protein test strip procedure are detected and clearly differentiated from other causes of proteinuria by their high alpha1-microglobulin/albumin ratios. In post-renal proteinuria, alpha2-macroglobulin proved to be a useful marker, when albumin excretion exceeds 100 mg/l urine. This protein exhibits plasma-like ratios to albumin in postrenal causes, whereas it is much lower in renal proteinurias. The new strategy, which has been evaluated in more than 500 clinically and partly histologically proven cases of renal diseases, more sensitively detects glomerular and tubulo-interstitial diseases when applied in urine screening and allows us to distinguish all clinically important causes from analysis of a morning spot urine sample.     

Meprin A, the major matrix degrading enzyme in renal tubules, produces a novel nidogen fragment in vitro and in vivo

We examined the effect of meprin A, the major matrix degrading metalloproteinase in rat kidney, on the laminin-nidogen complex. N-terminal sequence information from the most abundant 55 kDa fragment revealed that it was a breakdown product of nidogen rather than laminin. In comparison with over 50 nidogen cleavage sites produced by other proteases, the meprin A-induced nidogen cleavage site at amino acid position 899-900, a glutamine-glycine site in the G3 domain, is unique. In addition, these data demonstrate that meprin A degrades the G3 domain of nidogen even in the presence of laminin binding, which usually accords protection from proteolytic degradation. Meprin A also degraded purified nidogen into similar breakdown products. Given that the tubular basement membrane is located on the basilar side of the cell, the location of meprin A on the apical brush border makes it difficult to envision a role for meprin A in injury-induced basement membrane component breakdown. Thus, we examined the possibility that following renal tubular epithelial cell injury, meprin A undergoes a translocation to reach the underlying basement membrane. After renal ischemia-reperfusion there was a marked alteration in meprin A staining with meprin A now distributed throughout the renal tubular cell cytoplasm and directly adherent to the tubular basement membrane. This was in contrast to the usual linear staining of the brush border of tubules in the corticomedullary junction. These data provide unequivocal evidence that following injury, meprin A undergoes redistribution and/or adherence to the tubular basement membrane. Since in our in vitro studies, we identified a distinct meprin-induced 55 kDa nidogen breakdown product, the urine was also examined for the presence of nidogen degradation products after rat renal ischemia-reperfusion injury. Western blots showed a marked increase in the urinary 55 kDa nidogen fragment as early as the first day following ischemia-reperfusion injury and continuing for six days. Taken together, these in vivo data strongly support the notion that the nidogen breakdown products are the result of partial degradation of tubular basement membrane by meprin A following renal tubular ischemia-reperfusion injury.     

The effect of furosemide on renal blood flow and renal tissue oxygen tension in dogs

The effect of furosemide (2 mg/kg i.v.) on blood flowin the renal artery and the tissue oxygen tension of the renal cortex and medulla was investigated in six dogs. The flow was measured with an electromagnetic flowmeter and the tissue oxygen tension with IBC tissue oxygen electrodes. The flow in the renal artery increased significantly (p less than 0.05) 5-15 minutes after furosemide administration. 40 minutes after the injection the flow had returned to its initial level. The tissue oxygen tension of both the cortex and the medulla showed significant elevation following furosemide administration. The maximum increase of tissue oxygen tension was recorded 10-20 minutes after the injection. The oxygen tension values exceeded the initial level by 22% in the cortex and by 48% (p less than 0.001) in the medulla. Simultaneously, with the changes in oxygen tension, urine output increase considerably and urine osmolality declined. Application of these renal effects of furosemide in clinical work, particularly in cardiopulmonary bypass surgery, is discussed.     

普通碳素钢超细晶微观组织的特征分析

 用Gleeble热模拟实验机对2种不同成分的普通碳素钢进行实验，实验的过程为：以10 ℃/s加热到950 ℃，保温2 min，再以10 ℃/s的冷速降到变形温度(900~600 ℃)，以10 s-1或30 s-1的变形速率进行了变形量为80%的变形，变形后立即水淬。通过光学显微镜和透射电镜观察分析，确定了普通碳素钢利用形变诱导铁素体相变获得的超细晶组织及两相区变形获得的超细晶组织的典型形貌特征。     

Correspondence between stone composition and urine supersaturation in nephrolithiasis

Supersaturation (SS) with respect to calcium oxalate monohydrate (COM), brushite (Br) and uric acid (UA), obtained in three 24-hour pretreatment urine samples from patients with stone disease were compared to the mineral composition of stones passed by the same patients to determine whether sparse urine SS measurements accurately reflect the long-term average SS values in the kidney and final urine. Among males and females elevation of SS above same sex normals corresponded to composition. As well, treatments that reduced stone rates also reduced these SS values. The degree of calcium phosphate (CaP) admixture was accurately matched by shifting magnitudes of COM and Br SS. As well, increasing CaP content was associated with falling urine citrate and rising urine pH, suggesting renal tubular acidosis. We conclude that sparse urine SS measurements accurately track stone admixtures, and are a reliable index of average renal and urine SS.     

A PRELIMINARY STUDY OF THE REACTIONS BETWEEN TUNGSTEN CARBIDE AND TUNGSTEN CARBIDE - 6% COBALT POWDERS AND WET AND DRY HYDROGEN

Abstract

The apparent activation energy for the following reactions has been determined by measuring the amount of carbon removed from samples of powder heated to various temperatures in an atmosphere of either dry or wet hydrogen:

Dry Hydrogen

“As-carburized” tungsten carbide: no reaction up to 900°C.

Water–milled tungsten carbide: 8·38 kcal/mole over the range 600–900°C.

Water–milled tungsten carbide+ 6% cobalt: complex reaction over the range 600–900°C.

Wet Hydrogen

“As-carburized” tungsten carbide: 58·1 kcal/mole over the range 800–900°C.

Water–milled tungsten carbide: 34·8 kcal/mole over the range 700–900°C.

Water–milled tungsten carbide+ 6% cobalt: 38·4 kcal/mole over the range 825–900°C; 7·38 kcal/mole over the range 600–800°C.

It has been shown that ball-milling in water changes both the physical and chemical properties of tungsten carbide powder. These changes are discussed in relation to the marked differences in reaction rates. A number of possible reasons for these differences are given.     

Renal water channel expression in newborns: measurement of urinary excretion of aquaporin-2

Aquaporin-2 (AQP-2) encodes the vasopressin-regulated "water channels" of the renal collecting duct and is excreted in human urine. We measured urinary excretion of AQP-2 by radioimmunoassay in 15 term and 10 preterm infants on day 1 and day 4 of life to determine the molecular basis of water balance during the newborn period. AQP-2 was detectable in the urine of term and preterm newborns, but AQP-2 excretion was severalfold less than the reported level in normal adults. Urinary excretion of AQP-2 significantly decreased postnatally, in parallel with a reduction in urine osmolality and arginine vasopressin (AVP) excretion. Urinary AQP-2 correlated positively and significantly with urine osmolality on days 1 and 4 and with AVP on day 1 in both groups. No significant differences were detected in AQP-2 levels between term and preterm newborns. Our findings suggest that vasopressin-regulated water channels are expressed in the renal collecting duct of both term and preterm newborns, although to a lesser extent as compared with adults, and these channels encoded by AQP-2 contribute to the urine concentrating power of the newborn kidney.     

Probenecid inhibits the renal clearance and renal glucuronidation of nalidixic acid. A pilot experiment

The aim of this pilot study was to demonstrate the possible inhibitory effect of probenecid on the renal glucuronidation and on the renal clearance of nalidixic acid in a human volunteer. Under acidic urine conditions, hardly any nalidixic acid is excreted unchanged (0.2%). It is excreted as acyl glucuronide (53.4%), 7-hydroxymethylnalidixic acid (10.0%), the latter's acyl glucuronide 30.9%, and 7-carboxynalidixic acid (4.2%). Under probenecid co-medication the renal glucuronidation of nalidixic acid is reduced from 53% to 16%; the renal clearance of both nalidixic acid and 7-hydroxymethylnalidixic acid are reduced (p < 0.001); the intrinsic t1/2 of the metabolite 7-hydroxymethylnalidixic acid increased from 0.48 h to 4.24 h. The amount of acyl glucuronidation of 7-hydroxymethylnalidixic acid was not altered. The in vitro protein binding of both acyl glucuronides was increased, while no effect on the unconjugated compounds was seen. Nalidixic acid had no effect on the maximal renal excretion rate of probenecid acyl glucuronide.     

Urine specific gravity and osmolarity in hypertension patients with dehydration

Results are reported from the comparative investigations of kidney concentration function by urine specific gravity and its osmolatity of 58 patients with arterial hypertension. Significant differences were found in more of the half of the patients. On the base of certain theoretical prerequisites and possibilities of technical errors was concluded that the determination of the maximal urine osmolality is a more reliable and more accurate index for the actual renal concentration ability. Urine specific gravity can be used in the everyday clinical practice due to the more convenient and easier determination. Urine osmolality must be used predominantly in scientific-clinical studies.