08 July, 2011
Kidney Disease & Vitamin D Deficiency
Vitamin D deficiency is a common problem among those with chronic kidney disease. Vitamin D is a mineral that is found in plant and animal sources, dietary supplements, as well as synthesized from exposure of your skin to sunlight. Low levels of vitamin D can cause weak bones, muscle spasms, fractures and may even increase your risk of death if you have chronic kidney disease. Fortunately, this condition can be treated with a vitamin D supplement prescribed by your doctor.
Function of Vitamin D
According to The Merck Manuals Online Medical Library, there are two forms of vitamin D: an inactive and active form. Vitamin D2 and D3 are considered the inactive forms, while calcitriol is considered the active form. Vitamin D2 is found in plants, yeast and dietary supplements. Vitamin D3 is found in animal products and is also synthesized when your skin is exposed to sunlight. Vitamin D2 and D3 are converted to calcitriol by the liver and kidneys. Calcitriol is needed for the absorption of calcium and phosphorus in the intestines. Calcium and phosphorus, in turn, are needed to build bones and make them strong.
Vitamin D Deficiency and Kidney Disease
Vitamin D deficiency occurs commonly in those with kidney disease because the kidneys becomes damaged so that they are unable to convert the inactive form of vitamin D to calcitriol. According to DaVita, “about half of all chronic kidney disease patients who are not on dialysis and almost all of those on dialysis are not able to activate vitamin D into its usable form.”
Vitamin D deficiency can lead to problems such as muscle pain, muscle spasms, weak bones, fractures, bone pain, rickets, osteomalacia and other problems arising from elevated levels of calcium in the blood. Vitamin D deficiency may initially present with low levels of calcium in the blood, but over time may lead to elevated levels as the body tries to compensate by increasing the secretion of parathyroid hormone. High levels of calcium in the blood can cause calcium to be deposited in the tissues, leading to a heart attack, breathing problems and joint pain. “Renal and Urology News” notes that chronic kidney disease patients with vitamin D deficiency are at an increased risk of developing diabetes, insulin resistance, high blood pressure and elevated triglycerides. Patients on dialysis with low vitamin D and calcitriol levels also have a higher risk of death within 90 days of beginning dialysis.
A study published in 2010 in the “Clinical Journal of the American Society of Nephrology” discovered that the risk of vitamin D deficiency was highest among females, African-Americans, those with low levels of albumin in the blood and those starting dialysis in the winter. Participants with low albumin during the winter were at the greatest risk.
Your doctor may prescribe a vitamin D supplement for you if you have chronic kidney disease and vitamin D deficiency. You may need to be started on a high dose of a vitamin D2 supplement for about six to 12 weeks to replenish vitamin D stores, notes DaVita. If you have chronic kidney disease do not take an over-the-counter vitamin D supplement without consulting your doctor first, as this could be harmful to your health.
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