Tubular dysfunction in type I diabetes mellitus

Tubular function was investigated in patients with diabetic ketoacidosis and those with poorly controlled type I diabetes. Urinary excretion of beta 2 microglobulin and that of certain enzymes: gamma glutamyltransferase, leucine aminopeptidase, and N-acetyl-beta-D-glucosaminidase activities were significantly raised during ketoacidosis in 11 patients compared with healthy controls. In 13 poorly controlled diabetics, tubular electrolyte transport was studied and a significant reduction in tubular phosphate and sodium reabsorption was found. Tubular dysfunction occurring during diabetic ketoacidosis and in poorly controlled diabetics may contribute to the development of diabetic nephropathy.

Pathophysiological changes in rat kidneys with partial ureteral obstruction since infancy

A partial ureteral obstruction (PUO) was created in 5-day-old rats by implanting the left ureter in the psoas muscle. The surgical technique was modified to produce mild or severe hydronephrosis [Hn (m) and Hn (s)]. The rats were studied at ages between 45 and 65 days with regard to kidney weight, number of functioning glomeruli, mean arterial blood pressure (MAP), total glomerular filtration rate (GFR), nephron filtration rate (SNGFR), tubular free-flow pressure (PT, and stop-flow pressure (SFP). Total GFR was determined after the release of obstruction. The other studies were performed in the obstructed state. Reference values were obtained from sham-operated and untouched control rats. The number of functioning nephrons was depressed 38% in Hn (m) and 73% in Hn (s). Total GFR was preserved in Hn (m) and depressed 54% in Hn (s). SNGFR in the remaining nephrons was significantly elevated in Hn (m) and normal in Hn (s). SFP was significantly elevated in Hn (s). The Hn (s) rats were hypertensive. The glomerular density was lower in the hydronephrotic than in the contralateral kidneys. This suggests a compensatory growth of the remaining nephrons in the Hn kidneys. We conclude that PUO present since infancy will either destroy the nephrons or elicit an adaptive response that will tend to preserve GFR.

Estimation of glomerular filtration rate from plasma clearance of 51-chromium edetic acid

The glomerular filtration rate was estimated by a single compartment analysis of the rate of fall of plasma concentration of 51-chromium edetic acid after a single intravenous injection. This slope clearance consistently overestimated the simultaneously determined standard urinary clearance, but could be used to predict the latter with an accuracy of ±9% (95% confidence limits). The coefficient of variation of replicate estimates of the slope clearance in the same individual was 3·9%; thus two estimates of glomerular filtration rate by this technique which differ by 11% have a 95% probability of reflecting a genuine difference. The method requires an intravenous injection and blood samples at 2 and 4 hours; urine samples are not required. It is simple, safe, and precise, and is applicable to children.

Lower urinary obstruction in infancy. A review of lesions and symptoms in 165 cases

This paper reviews 165 cases of lower urinary obstruction in infancy. The commonest lesions were posterior urethral valves (91) and ectopic ureterocele (34), stenosis or atresia of the urethra (8), and bladder neck obstruction (6). There were 12 different diagnoses in the remaining 26 cases. The commonest presenting features were general in nature (110), and of these, failure to thrive and vomiting (87) were most frequent. The commonest urinary signs and symptoms were palpable bladder (93) and urinary infection (90). An accurate diagnosis was obtained by intravenous pyelography or cystourethrography. Treatment was directed to correction of electrolyte and water disturbances, followed by early relief of the obstruction. The mortality rate was 32·5% for children admitted in the first month of life, and only 8% thereafter, with an overall rate of 18%.