Vitamin D insufficiency and deficiency in chronic kidney disease - A single center observational study

Background: Kidney disease has been identified as a risk factor for vitamin D deficiency in hospitalized patients, and low levels of 25-hydroxyvitamin D have been suggested to be a risk factor for hyperparathyroidism in patients with chronic kidney disease (CKD). However, little is known about the magnitude of vitamin D deficiency in patients with CKD living in the United States. Methods: In this regard, we examined the levels of 25( OH) D in 43 patients with CKD and serum creatinine between 1 and 5 mg/dl ( calculated glomerular filtration rate 111 - 11 ml/min per 1.73 m(2)) as well as in 103 patients undergoing hemodialysis. Results: In the predialysis patients, we found that 37 of the 43 patients (86%) had suboptimal levels of vitamin D (<30 ng/ml). Regression analysis indicated that there was a negative correlation between 25( OH) D and intact parathyroid hormone (PTH). Alkaline phosphatase showed a similar but less sensitive relationship. Serum albumin levels correlated with 25( OH) D levels. In contrast to findings reported in normal individuals, the levels of calcitriol correlated with those of 25( OH) D in the patients with CKD. In the group undergoing maintenance hemodialyis, we found that 97% of the patients had vitamin D levels in the suboptimal range, and there was no correlation of 25( OH) D levels with either PTH or serum albumin values. These data indicate that vitamin D insufficiency and deficiency are highly prevalent in patients with CKD and may play a role in the development of hyperparathyroidism. The functional significance of low levels of 25( OH) D in patients with stage 5 CKD remains to be determined. Copyright (C) 2004 S. Karger AG, Basel.