Renal Acid-Base Disorders: Pathogenesis and Management

Calcagno, Philip L.; D’Albora, James B.

doi:10.1016/s0031-3955(16)31586-3

Cited by 4 publications

(1 citation statement)

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“…This possibility has brrn suspected in the syndromes of FANCONI [46] and LOWE [13,34,571, although only a frw bicarbonate rrabsorption studirs h a w bern rcportrd. In Fanconi syndromr low bicarbonatc thrcshold [7,48,591 ancl 'Tm of rrabsorption 148, 591 havc been found, and when scrum bicarbonatc was below the thrcshold value paticnts havr had acid urinrs and hydrogen excrrtion adequate for the Ievrl ofglomrrular filtration [59]. I n K. J., although all trstsof tubularfunctionothrr than bicarbonatr rcabsorption were normal, the possibility of a gradual srquential development of othrr tubular defrcts, as has been rrportcd by LCJIIEN and SIIELDON [40,671 and BLOOMER et (11.…”

Section: Hicarbotlnte Reab~or/ition In Secorzdnyj R T Amentioning

confidence: 99%

Proximal Renal Tubular Acidosis. A Defect in Bicarbonate Reabsorption with Normal Urinary Acidification

et al. 1967

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ExtractThisreport concerns two patients with primary renal tubular acidosis (RTA) in whom the abnormality in hydrogen excretion was shown to result from inappropriate urinary loss of bicarbonate due to a low renal hicarbonate threshold. O n the basis of the findings, a new definition and reclassification of RTA is proposed.. .The clinical course and response to medication is illustrated in figs. 1-4. Repeated measurements of clearances of creatinine, inulin, and PAH gave normal values (table I).Excretion of aminoacids (table 11) was normal in both patients. After water restriction, the urinary osmolality was 990 mOsm/kg water for K. J. and 1088 mOsm/kg water for S.G. No reducing substance was found in the urine of K. J. ; glucose was present in trace amounts on several occasions in the urine of S.G. Tul~ular real~sorption of phosphate was always in the normal range, 80 to 90 percent of the filtered amount. Both children had an adequate response to the oral administration of ammonium chloride, providing no alkali therapy was being administered at the time of the test (table 111).In fig. 5, rates of reabsorption and excretion of bicarbonate, expressed as mmoles/100 ml glomerular filtrate (GF) are plotted against serum bicarbonate concentration in mmoles/liter. Data from 2 studies are included in the figure. K. J. started to excrete bicarbonate into the urine at a serum bicarbonate level of 18 to 19 mmoles/liter; the T m of reabsorption was low, being approximately 2.1 mmoles/100 ml GF. In S.G., although the threshold was similarly depressed (19 to 20 mmoles/liter), the T m of reabsorption was at the lower limit of the normal range (2.5 to 2.6 mmoles/100 ml GF).The ratio of reabsorbed bicarbonate to T m has been plotted as a function of the ratio of filtered l~icarbonate to T m ( fig. 6). The data from the studies in K. J. demonstrate a splay very similar to that of normal infants. S.G., however, has a markedly increased splay. During bicarbonate infusion and when rates of bicarbonate reabsorption were near the Tm, acetazolamide was administered intravenously in a single dose of 100 mg. In both children, marked inhibition of bicarbonate reabsorption was demonstrated. At similar rates offiltered bicarbonate, the urinary excretion increased two-to-three-fold with a concomitant decrease in the rate ofreabsorption (table V).Results for glucose reabsorption in K.J. are close to those of normal adults with a threshold of 300 mg/min/1.73 m2 and a T m of over 400. In contrast, S.G. had small amounts of glucose in the control urines and the glucose threshold was abnormally low, approximately 100 mgImin11.73 m2. Although blood glucose was not maintained at high values long enough to be certain that the T m had been reached, values as high as 327 mg/min/1.73 m2 were obtained, suggesting that his glucose T m was normal.After administration of histamine, the acidity of the gastric fluid increased markedly and the values of free acid and total titratable acid compare closely with that of normal children (table VI).Histologic exa...

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Section: Hicarbotlnte Reab~or/ition In Secorzdnyj R T Amentioning

confidence: 99%