The renal excretion of hydrogen ion in renal tubular acidosis. I. quantitative assessment of the response to ammonium chloride as an acid load

Urinary citrate excretion in the diagnosis of distal renal tubular acidosis

Since hypocitraturia in distal renal tubular acidosis, we screened the asymptomatic children in three families with familial dRTA, by comparing their 24-hour urine citrate excretion to values obtained in 45 normal children. Subsequent acid loading uncovered four new cases of dRTA suspected because of the finding of hypocitraturia. Because hypocitraturia probably contributes to nephrolithiasis/nephrocalcinosis and subsequent renal damage in dRTA, affected family members were treated with alkali (4 mEq/kg/day), which normalized urine citrate in three children; in a fourth child citrate excretion rose but was not normal. Measurement of urine citrate excretion was superior to other currently proposed screening tests for dRTA (first morning urine pH and sediment, urine concentration).

Amelioration of metabolic acidosis with fludrocortisone therapy in hyporeninemic hypoaldosteronism

In four patients with renal hyperchloremic acidosis and hyperkalemia, hyporeninemic hypoaldosteronism and chronic renal insufficiency (glomerular filtration rates of 13, 31, 35 and 44 ml per minute per 1.73 m2), prolonged administration of fludrocortisone increased urinary potassium and net acid excretion, corrected hyperkalemia and substantially ameliorated acidosis. Except in the patient with the lowest glomerular filtration rate, the increased net acid excretion was due mostly to increased ammonium excretion. Urine pH decreased initially in each patient, but in the three patients with the highest filtration rates, it increased subsequently as ammonium excretion increased, indicating that renal ammonia production increased. Urinary ammonium excretion correlated inversely with serum potassium concentration and did not decrease on discontinuation of therapy if hyperkalemia was prevented from recurring. In patients with renal acidosis and hyporeninemic hypoaldosteronism, administration of mineralocorticoid hormone can augment both renal hydrogen-ion secretion and, by correction of hyperkalemia, renal ammonia production, and thereby ameliorate metabolic acidosis.

Primary renal tubular acidosis recognized and treated at three days of age. A case report illustrating the value of routine postmortem examination

Renal tubular acidosis should be suspected even in the very young in fant who does not thrive, and who demonstrates a hyperchloremic acidosis with urine of neutral pH. This case report details the course of an infant whose disease was diagnosed in the newborn nursery.

Hypercalcaemia, hypophosphataemia, and inability to excrete hydrogen ions

Investigation of a patient with hypercalcaemia, hypophosphataemia, and nephrocalcinosis failed to lead to a clear diagnosis. Neither primary hyperparathyroidism nor primary incomplete renal tubular acidosis could explain all the biochemical features, and it seems that more than one fundamental abnormality may have been present.

Renal tubular acidosis in infants: the several kinds, including bicarbonate-wasting, classic renal tubular acidosis

In four infants with renal tubular acidosis (RTA), including three with apparently classic RTA and one with Fanconi syndrome (FS), the physiologic character of the renal acidification defect was investigated. In two of the infants with apparently classic RTA, the acidification defect was physiologically separable from that described in both adult patients and children with classic RTA (type 1 RTA) in the following ways. (a) The fractional excretion of filtered bicarbonate (C(HCO3)/C(ln)) was not trivial but substantial (6-9%), as well as relatively fixed, over a broad range of plasma bicarbonate concentrations (15-26 mmoles/liter). (b) This value of C(HCO3)/C(ln), combined with a normal or near normal glomerular filtration rate, translated to renal bicarbonate wasting (RBW). (c) RBW at normal plasma bicarbonate concentrations was the major cause of acidosis, and its magnitude was the major determinant of corrective alkali therapy (5-9 mEq/kg per day), just as in the patient with FS, who was found to have type 2 ("proximal") RTA. (d) Persistence of RBW at substantially reduced plasma bicarbonate concentrations, which did not occur in FS, accounted for the spontaneous occurrence of severe acidosis and its rapid recurrence after reduction in alkali therapy. (e) During severe acidosis the urinary pH was >7, a finding reported frequently in infants with apparently classic RTA and "alkali-resistant" acidosis but rarely in adult patients with classic RTA. Continued supplements of potassium were required to maintain normokalemia during sustained correction of acidosis with alkali therapy. Yet, in at least two of the three infants with apparently classic RTA, but in distinction from the patient with FS and other patients with type 2 RTA, fractional excretion of filtered potassium decreased when plasma bicarbonate was experimentally increased to normal values. In one of the two infants with apparently classic RTA and RBW, C(HCO3)/C(ln) and the therapeutic alkali requirement decreased concomitantly and progressively over 2 yr, but RBW continued. Renal tubular acidosis has persisted in all four patients for at least 3 yr, and in three for 4 years.

A case of bicarbonate-losing renal tubular acidosis with defective carboanhydrase activity

A girl of 20 months had primary proximal renal tubular acidosis with a lowered renal threshold for bicarbonate. There was no carboanhydrase inhibition after acetazolamide administration, suggesting that defective carboanhydrase activity may have been causative.