Hypovitaminosis D and an Inadequate PTH Response in Chronic Liver Disease Patients

Hypovitaminosis D is a common condition found in patients referred for orthotopic liver transplant. The classical physiologic response to vitamin D deficiency is the development of secondary hyperparathyroidism. However, several previous studies have found a high incidence of inappropriate functional hypoparathyroidism in patients with chronic liver disease and hypovitaminosis D. The mechanism underlying this functional hypoparathyroidism is not understood but previous investigators have postulated that it is related to intracellular magnesium (Mg) deficiency. Our short term goals of this pilot project are two fold: (a) We will estimate the prevalence of magnesium deficiency in chronic liver disease patients by performing standard Mg loading testing (b) We will examine the effects of acute intravenous Mg infusion on the calcium-PTH axis. The vitamin D-PTH endocrine system is one of the principal regulators of calcium homeostasis and bone metabolism. Metabolic bone disease is a quite pervasive problem in chronic liver disease patients. Insight into this important endocrine system will aid us in our long term goals of addressing metabolic bone disease issues in this patient population.