People with renal insufficiency are at high risk of vitamin D deficiency. A March 2010 article by Ishar Bhan appearing in the "Clinical Journal of the American Society of Nephrology" found that 79 percent of the 1,908 patients studied were vitamin D-deficient. Consuming excess vitamin D in the form of food or sunshine does not necessarily remedy this problem.
Names
The name "vitamin D" is a bit of a misnomer because it refers to a number of different compounds. The vitamin D that we get from the sun and from dietary sources is more properly called cholecalciferal. The liver transforms cholecalciferal into 25-hydroxycholecalciferol, also called 25-hydroxyvitamin D. The kidneys, in turn, transform 25-hydroxycholecalciferol produced into the biologically active 1,25-dihydroxycholecalciferol, also called 1,25 dihydroxyvitamin D or calcitriol.
Renal Issues
Patients with impaired renal function are often unable to convert vitamin D to his biologically active form. If you have severely impaired kidney function, it doesn't matter how much sun you get or who many high vitamin D foods you eat because none of this vitamin D is biologically active.
Treatment
Patients with impaired kidney function are at risk for weak bones because they often have high levels of serum phosphorus, which pulls calcium from the bone. This condition can be further aggravated by the vitamin D deficiency because this vitamin is essential for balancing levels of calcium and phosphorus. Fractures are commonplace, and rickets and osteomalacia, a bone disorder found in adults, can result.
Warning
In some instances, nephrologists may decide not to treat vitamin D deficiencies. For example, in some people, increased vitamin D might cause calcium to be removed from bone, causing painful calcium deposits on the joints and on blood vessels. Deciding to whether to treat this deficiency requires a careful analysis of phosphorus, calcium and parathyroid hormone levels. Patients should never decide to treat such deficiencies without consulting their doctor because they could easily make the situation worse.
References
- Colorado State University: Vitamin D
- "Clinical Journal of the American Society of Nephrology;" Clinical Measures Identify Vitamin D Deficiency in Dialysis; Ishir Bhan, et al; March, 2010
- "Clinical "Journal of the American Society of Nephrology;" Vitamin D and Kidney Disease; Wisam Al-Badr, et al.; Sept. 2008
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Calcium and Vitamin D: Important at Every Age
- Davita: Vitamin D and Chronic Kidney Disease
