Hyperkalemia in familial mitochondrial cytopathy.

AIM: To contribute to understanding the pathogenesis of hyperkalemia that often occurs in patients with diabetes.

MATERIALS AND METHODS: We describe 3 familial cases of mitochondrial diabetes mellitus. The mitochondrial A3243G point mutation was confirmed in a mother and her 2 children. We examined their clinical features and pathological findings, and assessed heteroplasmy of mutant mitochondria DNA (mtDNA) by molecular analysis.

RESULTS: The second son had spontaneous hyperkalemia and hyporeninemic hypoaldosteronism. Histopathological examination revealed severe tubulointerstitial and vascular changes around the juxtaglomerular apparatus. The mother only showed intermittent hyperkalemia concurrently with the aggravation of heart failure, and the pathological changes in her kidneys were mild. Heteroplasmy was more severe in the second son than in the mother.

CONCLUSION: Heteroplasmy of mitochondrial cytopathy combined with diabetes mellitus led to abnormalities resembling those seen in Type IV renal tubular acidosis.