| [ Summary ] |
In patients with chronic kidney disease (CKD), vitamin D deficiency is highly prevalent as early as at CKD stage G3. This condition is inversely associated with secondary hyperparathyroidism, progression of kidney dysfunction, and increased risk of mortality. Non-active (natural/nutritional) vitamin D is cost-effective with a low risk of hypercalcemia. Supplementation may increase serum levels to 1,25(OH)2D concentrations and decreases plasma parathyroid hormone (PTH) levels. As a result, the prevalence of nutritional vitamin D supplementation has rapidly increased in the United States, where approximately half of CKD patients are currently being prescribed vitamin D. In Japan, although measurement of serum level of 25(OH)D concentration is recently available, physicians can not prescribe non-active vitamin D as a medical treatment. To clarify the clinical relevance of non-active vitamin D, there is a need to determine optimal concentrations of 25(OH)D and the usefulness of measuring free/bioactive 25(OH)D, as well as testing the effectiveness of combined active and non-active vitamin D agents for CKD patients. |