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[Validity of diagnostic methods for kidney function tests in the cat].
The diagnosis of kidney disease is difficult in the stage of compensation and impossible based solely on the routinely performed laboratory tests on blood and urine. For this reason, more sensitive methods are required. In the present study, three special techniques are compared with regard to their validity in the early diagnosis of kidney disease in the cat: 1. the molecular-weight related separation of urine proteins with the sodium-dodecyl-sulfate-polyacrylamide-gradient gel electrophoresis (SDS-page) in the PhastSystem, 2. measurement of the glomerular filtration rate (GFR) with the renalyzer PRX90 using an iodine containing contrast medium and 3. kidney scintigraphy. The results of this comparison demonstrate that these procedures are important adjuncts to common laboratory investigations in the testing of renal function. The SDS-page allows an early qualitative assessment on alterations of specific functional compartments of the kidney. However, it is not possible with this method alone to evaluate the degree of renal disturbance and it does not give information concerning the severity of renal functional impairment. Measurement of the GFR is also a valuable procedure which gives a quantitative result on the global renal function within a few hours. It is of special importance when subclinically disturbed kidney function is present. In the cat however it is until now not possible to give a correct prognosis in high grade nephropathies. Only scintigraphy allows unilateral assessment of renal function, which is most important in cats with morphologically altered kidneys, such as kidney cysts, hydronephrosis or tumours.
Fetal serum concentrations of cystatin C and beta2-microglobulin as predictors of postnatal kidney function.
OBJECTIVES: Cystatin C and beta(2)-microglobulin are established serum markers of renal function in children and adults. In contrast to creatinine, diaplacental exchange is minimal. The aim of the study was to establish reference values in fetal serum and to test their efficiency in predicting postnatal kidney function. STUDY DESIGN: This was a prospective noninterventional study measuring cystatin C and beta(2)-microglobulin by particle-enhanced immunoturbidimetry in excess serum from 129 cordocenteses performed in 84 fetuses. Reference intervals (mean +/- 1.96 SD) were calculated in a subgroup of 54 fetuses without evidence of kidney disease, and these reference values were evaluated in 75 sera from 55 fetuses. RESULTS: Mean cystatin C was 1.66 +/- 0.202 mg/L (upper limit 2.06), and mean beta(2)-microglobulin was 4.25 +/- 0.734 mg/L. Unlike cystatin C, beta(2)-microglobulin decreased significantly with gestational age so that the upper reference limit was 7.19-0.052 x gestational age in weeks. beta(2)-Microglobulin had higher sensitivity (90.0% vs 63.6%) and cystatin C a higher specificity (91.8% vs. 85.5%) for the prediction of impaired renal function; diagnostic efficiency was equal (87.6% vs. 86.1%). Fetuses with impaired renal function at birth or who were aborted for renal malformations had higher cystatin C concentrations than those in a control group. beta(2)-Microglobulin was increased only in fetuses who were aborted. CONCLUSION: Fetal serum cystatin C and beta(2)-microglobulin concentrations may be useful predictors of postnatal kidney function.
Maillard reaction products and lysinoalanine: urinary excretion and the effects on kidney function of preterm infants fed heat-processed milk formula.
Heat processing is essential for the preservation of milk-based infant formulas. Heating, however, induces a number of chemical changes during which lysine in the milk proteins reacts with reducing sugars to form Maillard reaction products (MRPs) and also reacts with the dehydroalanine resulting from cystine degradation to form lysinoalanine (LAL). Both products have been reported to induce histological changes in the straight portion of the proximal tubule in the rat kidney. This pilot study was made to investigate the urinary excretion by healthy preterm babies of MRPs and LAL contained in infant formula and to determine their influence on kidney function. Twelve healthy male preterm babies were first fed for 10 days with pooled human milk and then for 5 days with each of two experimental premature infant formulas in a cross-over design. The infant formulas were sterilized either by ultra-high temperature (UHT) treatment or by a conventional retort process to give products with low and high levels of MRPs and LAL, respectively. In total, some 15.6% of the initial lysine had been modified in the in-can-sterilized product, compared to 6.2% in the UHT product. Urinary excretion of MRP lactulosyllysine ranged from 1.3 to 3.9% of the ingested amount, whereas that of LAL ranged from 6.2 to 9.3%. The higher level of MRPs and LAL in the formulas compared to breast milk had no influence on creatinine clearance or electrolyte excretion. There was no evidence of tubular damage as determined by the urinary excretion of four kidney-derived enzymes. Feeding of formula, however, did result in a general increase in urinary microprotein levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Fetal compensatory renal hypertrophy with a unilateral functioning kidney.
OBJECTIVE: To evaluate the possibility of fetal compensatory renal hypertrophy with a unilateral functioning kidney. METHODS: A nomogram of renal length was established from 254 normal fetuses. Renal length was also obtained in 14 fetuses with unilateral renal agenesis and 22 fetuses with a unilateral multicystic kidney. RESULTS: Compensatory renal hypertrophy, defined as a renal length > 95th percentile for gestational age, occurred in 16 of 36 cases (44.4%). CONCLUSIONS: Compensatory renal hypertrophy is detectable in utero and may occur as early as 22 weeks' gestation.
Kidney function and size in normal subjects before and during growth hormone administration for one week.
Kidney function and size were studied in seven normal male subjects before and after administration of highly purified human growth hormone for 1 week. Glomerular filtration rate, renal plasma flow (steady-state infusion technique with urinary collections using 125I-iothalamate and 131I-hippuran) kidney size (ultrasonic scanning) and urinary excretion rates of albumin and beta 2-microglobulin (radioimmunoassays) were measured. Highly purified growth hormone was injected subcutaneously, 2 IU in the morning and 4 IU in the evening. Glomerular filtration rate increased from (mean +/- SEM) 114 +/- 5 to 125 +/- 4 ml/min x 1.73 m2 (P less than 0.01) and renal plasma flow increased from 554 +/- 30 to 601 +/- 36 ml/min x 1.73 m2 (P less than 0.01). Kidney size and urinary excretion rates of albumin and beta 2-microglobulin did not change significantly. Our results show that raising plasma growth hormone into a range similar to that found in insulin-dependent diabetics enhances glomerular filtration rate and renal plasma flow, while kidney size remains unchanged. Increased renal plasma flow is the major determinant of growth hormone induced elevation in glomerular filtration rate. Growth hormone may thus contribute to the enhancement of glomerular filtration rate and renal plasma flow typically found in insulin-dependent diabetics.
Effects of obstruction on single-kidney function: clinical and experimental results with 131I-hippurate and 99mTc-DMSA.
In 35 patients, renography with 131I-o-hippurate (OIH) and static renal imaging with 99mTc-dimercaptosuccinic acid (DMSA) were used to measure differential renal function (DRF). The results were compared. Depth correction was applied in both methods. In non-obstructed kidneys (19 patients), both methods revealed nearly identical kidney function (r = 0.98). For completely obstructed kidneys (16 patients), OIH gave a significantly better DRF (14 ml/min) than DMSA. This small difference was of no clinical value. Because DMSA is reported to give unreliable results in unilateral obstructed kidneys, the right ureter was ligated in 8 dogs for 10 days and DRF was measured before and after opening an ureteral fistula. The difference in DRF was about 1% and could be accounted for by the amount of urinary radioactivity collected from the pelvic system after the ligature had been opened. Although DMSA appears to give reliable values in determining DRF, even in obstructed kidneys, OIH is preferred since total clearance values and postrenal urinary dynamics can be determined simultaneously.
Effect of C10-C11 isoparaffinic solvent on kidney function in Fischer 344 rats during eight weeks of inhalation.
Two groups of 50 male and 50 female Fischer 344 rats were exposed by inhalation to either 5.48 g/m3 (900 ppm) or 1.83 g/m3 (300 ppm) of C10-C11 isoparaffin (IP) 6 hr/day, 5 days/week for 8 weeks to evaluate renal function and histologic effects. Another group of rats (50/sex) was air exposed and served as controls. Urine and blood were collected from 10 male and 10 female rats of each group after 1, 4, and 8 weeks, and following a 4-week period of recovery. The ability of males to concentrate urine was reduced at 4 and 8 weeks of exposure to either level of IP. Following the 4-week recovery period, the urine concentrating ability of the exposed groups showed evidence of recovery. Following 4 and 8 weeks of exposure, glucose, protein, and epithelial cell excretion in urine of males was higher in the exposed groups than in that of controls. Creatinine clearance decreased after 8 weeks in the male high exposure group. After 4 weeks of recovery, urine glucose, protein, epithelial cell exfoliation, and creatinine clearance returned to control levels in exposed male rats. Overall, the effect on kidney function in male rats was mild, with evidence of near complete recovery. Histologic changes in exposed male rats compared to controls included an increased incidence of regenerative tubular epithelia and tubules dilated at the corticomedullary junction with proteinaceous debris in the tubules. No functional or histologic changes were observed in exposed female rats.
Mifentidine: evaluation of antiandrogen effects and kidney function studies.
Among a number of investigations aimed at evaluating the safety profile of a new antihistamine (H2), N1-[(4-imidazolyl)-phenyl]-N2-isopropyl-formamidine (mifentidine), its effects on male accessory sexual organs and on kidney function were studied in greater detail because of the known propensity of H2-antagonists to cause antiandrogenic activity and to alter renal function. Mifentidine (190 and 380 mg/kg p.o.) was compared to cimetidine (475 and 950 mg/kg p.o.) for its ability to affect growth of seminal vesicles and prostate of immature castrated rats treated either with testosterone (TP) or 5-alpha-dihydrotestosterone (DHT). Lower doses of mifentidine were investigated because, in terms of H2-antagonistic activity, it was shown to be several times (15 to 30) as potent as cimetidine. Cimetidine at the highest dose (950 mg/kg) reduced prostate growth sustained by TP, and the DHT-promoted growth of seminal vesicles and prostate. Mifentidine had no effect on hormone promoted growth of male accessory sexual organs. Renal function studies after repeated (7 days) administration of mifentidine (150 and 600 mg/kg p.o.) and cimetidine (1500 mg/kg p.o.) revealed a significant increase of the excreted fraction of filtered sodium (FeNa) and potassium (FeK) only after cimetidine, indicating altered tubular reabsorption. Creatinine and urea clearances were unchanged by either drug treatment. Thus mifentidine appears to be devoid of antiandrogenic activity and renal effects.
[Kidney function tests of practical value].
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Simultaneous direct and indirect inulin clearance as a separate kidney function test.
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[Endogenous creatinine excretion; its use as kidney function test].
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[Modern kidney function tests in childhood].
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[Significance of urinary volume in kidney function tests].
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Occupational exposure to lead, kidney function tests, and blood pressure.
In the present study we examined sensitive biochemical markers of kidney function and damage in 166 workers exposed to lead and in 60 control workers. The objective was to investigate the chronic renal toxicity of lead and its possible correlation with arterial pressure. Diastolic arterial pressure was higher in the exposed group (p < 0.05), but the two groups did not differ in systolic pressure. Median activity of urinary N-acetyl-beta-D-glucosaminidase was higher in the exposed group (p < 0.001), and correlated with blood lead levels (p < 0.001) and duration of exposure (p < 0.001), but not with arterial pressure. The other indicators studied, gamma-glutamyl-transpeptidase and alanine-aminopeptidase activity, urine albumin, and total urine protein, were not higher than in the control group and were not correlated with blood lead, duration of exposure, or arterial pressure.
Hydrocarbon exposure, hypertension and kidney function tests.
Control and hydrocarbon exposed workers participated in a cross-sectional study about the nephrotoxicity of chronic hydrocarbon exposure. Different markers of glomerular and tubular function as well as the celluria were examined and compared. The results show that the interaction between hypertension and hydrocarbon exposure has an influence on the kidney function. For the clearance the interaction age-exposure seems to play a more important role than age or exposure alone. The most useful markers appear to be the albuminuria, the N-acetyl-beta-D-glucosaminidase activity, the retinol-binding-protein concentration and the creatinine clearance.
Effect of captopril on kidney function in insulin-dependent diabetic patients with nephropathy.
The influence of angiotensin II on kidney function in diabetic nephropathy was assessed by studying the effect of 12 weeks' monotherapy with captopril (25-50 mg twice a day) in 16 hypertensive insulin dependent diabetic patients with persistent albuminuria. In an initial one week randomised single blind trial of captopril versus placebo, captopril (for nine patients) reduced arterial blood pressure from 148/94 (SD11/6) to 135/88 (8/7) mm Hg (p less than 0.05) and albuminuria from 1549 (range 352-2238) to 1170 (297-2198) micrograms/min (p less than 0.05), while glomerular filtration rate remained stable. No significant changes occurred in seven patients treated with placebo. During the 12 weeks of captopril treatment arterial blood pressure in all patients fell from 147/94 (11/6) to 135/86 (13/7) mm Hg (p less than 0.01), albuminuria fell from 1589 (range 168-2588) to 1075 (35-2647) micrograms/min (p less than 0.01), and glomerular filtration rate fell from 99 (SD19) to 93 (25) ml/min/1.73 m2 (p less than 0.01). The renin-angiotensin system showed suppressed plasma concentrations of angiotensin II and increased concentrations of angiotensin I and renin. The study showed that glomerular filtration rate is not dependent on angiotensin II, that captopril reduces albuminuria, probably by lowering glomerular hypertension, and that captopril represents a valuable new drug for treating hypertension in diabetics dependent on insulin with nephropathy.
Kidney function and glomerulopathy over 8 years in young patients with Type I (insulin-dependent) diabetes mellitus and microalbuminuria.
AIMS/HYPOTHESIS: We aimed to investigate prospectively the interrelation between kidney function and glomerular morphological changes over 8 years in young patients with Type I (insulin-dependent) diabetes mellitus and microalbuminuria. METHODS: Kidney biopsies were taken at baseline and after 8 years in 18 subjects who were 20 years of age (19-29 mean and range), had duration of diabetes for 11 years (7-18), and who had an albumin excretion rate of 45 microg/min (15-194). The glomerular ultrastructural parameters were analysed using stereological methods. RESULTS: At the end of the study three patients had an increased albumin excretion rate of more than 25 % a year, two of whom developed overt nephropathy. Glomerular filtration rate declined 2.3 ml/min x 1.73 m(-2) x yr(-1). Glomerular volume, volume fractions of matrix and mesangium, and basement membrane thickness showed an increase over the 8 years. Multiple regression analysis showed that mean 8-years HbA(1 c), matrix volume fraction(baseline) and basement membrane thickness BMT(baseline) accounted for 70 % of the variation in AER at the end of the study. Mesangial volume fraction(baseline,) glomerular filtration fraction(baseline,) and mean 8-year HbA(1 c) accounted for 73 % of the change in glomerular filtration rate from baseline. Smoking was strongly associated with the glomerular filtration rate at baseline ( r = 0.65). When glomerular filtration rate(baseline) was omitted from the equation, smoking was the only significant parameter linked to the change in glomerular filtration rate from the baseline. CONCLUSION/INTERPRETATION: In patients who had diabetes for 20 years, long-term hyperglycaemia and glomerulopathy found 8 years prior to the study, and possibly smoking, affected renal function (i. e. albumin excretion rate and glomerular filtration rate).