vitamin-b-12 and Hyperkalemia

The patients affected by vitamin B12-unresponsive methylmalonic acidemia (MMA) on the long run develop chronic renal disease with interstitial nephropathy and progressive renal insufficiency. The mechanism of nephrotoxicity in vitamin B12-unresponsive MMA is not yet known. Chronic hyporeninemic hypoaldosteronism has been found in many cases of methylmalonic acidemia, hyperkalemia and renal tubular acidosis type 4. We report 2 patients affected by B12-unresponsive methylmalonic acidemia diagnosed at the age of 23 months and 5 years, respectively, with normal glomerular filtration and function. They showed hyporeninemic hypoaldosteronism and significant hyperkalemia requiring sodium potassium exchange resin (Kayexalate) therapy after an episode of metabolic decompensation leading to diagnosis of MMA. In both children, hyporeninemic hypoaldosteronism and hyperkalemia disappeared after 6 months of good metabolic control.

Topics: Child, Preschool; Female; Fumarates; Humans; Hyperkalemia; Hypoaldosteronism; Infant; Kidney; Male; Maleates; Metabolism, Inborn Errors; Vitamin B 12

Persistent hyperkalaemia was found in a patient with vitamin B12 unresponsive methylmalonic acidaemia associated with hyperuricaemia. At 3 years and 8 months of age, a serum potassium level of 6.8 mmol L-1 was found when blood gas measurement was normal. One year later azotaemia was noted. At the age of 5 years, renal function studies disclosed hyperaldosteronism, decreased creatinine clearance, reduction of the reabsorption of sodium at distal diluting segments and inadequate concentration of urine at the collecting ducts. The reduction of the reabsorption of sodium, which may have resulted in decreased potassium excretion, and the decrease in glomerular filtration rate, together with the superimposed excess intake of potassium, appeared to be responsible for the hyperkalaemia. Dietary potassium restriction was effective in suppressing the hyperkalaemia.

Topics: Child; Female; Glomerular Filtration Rate; Humans; Hyperaldosteronism; Hyperkalemia; Malonates; Metabolism, Inborn Errors; Methylmalonic Acid; Uremia; Uric Acid; Vitamin B 12