Renal hypomagnesemia, hypercalciuria and nephrocalcinosis in a middle-aged man.

We report a 41-year-old man with hypomagnesemia, hypercalciuria, nephrocalcinosis, myopia and horizontal nystagmus. The hypomagnesemia was due to primary renal magnesium loss. He was diagnosed as having the syndrome of renal hypomagnesemia, hypercalciuria and nephrocalcinosis. This is a rare condition generally diagnosed by the first to third decades of life. Renal failure is common and end-stage renal disease can occur in children or young adults. The patient was treated with oral magnesium, chlorthalidone, potassium citrate and allopurinol and was followed up for 3 years. Treatment resulted in an improvement in hypercalciuria but serum magnesium level could not be normalized. The patient's renal function remains stable, with a mild degree of renal insufficiency.