Hypomagnesemia and impaired parathyroid hormone secretion in chronic renal disease.

Severe hypocalcemia secondary to magnesium depletion has been described in numerous patients with gastrointestinal disorders. The development of profound hypomagnesemia in chronic renal disease is a rare finding. We studied three patients with advanced renal failure and magnesium depletion. Severe hypocalcemia also was present in these patients. Despite hyperplasia of the parathyroid glands, the levels of immunoreactive parathyroid hormone (PTH) in blood were inappropriately low for the degree of renal insufficiency. After the administration of magnesium there was a significant increase in the levels of circulating i-PTH in serum with a concomitant improvement in the hypocalcemia.