Pediatr Nephrol. 2006 Mar 2; [Epub ahead of print]
Hyperkalemic distal renal tubular acidosis associated with Rett syndrome
Assadi F, Crowe C, Rouhi O.
Abstract
Renal function was studied in a 7-year-old girl with Rett syndrome (RS) complicated by persistent hyperchloremic hyperkalemic metabolic acidosis. The acidosis was associated with a urine pH above 5.5, positive urinary anion gap and decreased potassium excretion. Plasma renin activity, aldosterone and cortisol levels were normal. Therapy with sodium bicarbonate failed to lower urine pH below 5.5 or increase potassium excretion. Hydrochlorothiazide administration resulted in a fall in urine pH below 5.5 and an increase in potassium excretion as a result of increased distal sodium delivery and increased sodium reabsorption in the distal nephron. We conclude that a voltage-dependent type of derangement in the distal nephron, rather than aldosterone deficiency, is responsible for the impairment in urinary acidification observed in this patient. Early detection of impaired renal acidification in RS may prevent or slow the progression of growth failure.
Lay Summary
In this case study, doctors describe a 7-year-old girl with Rett syndrome with altered kidney function. A feature not previously described in Rett syndrome, they describe the co-occurrence of a condition known as "hyperchloremic hyperkalemic metabolic acidosis". The key point in this article is that they suggest that early diagnosis of altered kidney function may be important in Rett syndrome, as medical interventions are available to prevent or slow progression of such types of kidney failure.