The purpose of this study is to determine how common low levels of magnesium are in patients with end stage liver disease. In addition, investigator is trying to determine if low levels of magnesium affect the release of parathyroid hormone in patients with end stage liver disease and low vitamin D levels

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.

Inclusion Criteria:

chronic liver disease patients > 18 years of age Diagnosed end stage liver disease >18 years of age Presence of hypovitaminosis D Glomerular filtration rate of 60 ml/min./1.73m2 or greater

Exclusion Criteria:

subjects with known parathyroid disease subjects taking magnesium supplementation <18 years of age History of parathyroid disease Current supplementation of magnesium Abnormal baseline EKG Current diagnosis of cancer or undergoing cancer treatment