Vitamin D overdose goes by the medical terms hypervitaminosis D or vitamin D toxicity. Vitamin D is a fat-soluble vitamin that's stored in your liver and body fat, and this makes toxicity more likely than if you took too much of a water-soluble vitamin. Vitamin D overdose is rare; however, if you have specific medical conditions or take certain drugs, this may make you more susceptible to toxicity if you take supplemental vitamin D.
Symptoms
According to MedlinePlus, when vitamin D toxicity occurs, it's usually in people who use doctor-prescribed supplements. Symptoms of hypervitaminosis D include constipation, lethargy, dehydration, confusion, nausea, vomiting and a flagging appetite. Vitamin D overdose can have serious consequences, causing extensive damage to bones, kidneys and other organs. Mayo Clinic nutritionist Katherine Zeratsky indicates that the primary complication of vitamin D toxicity is hypercalcemia, a condition in which the calcium levels in your blood are abnormally high. Hypercalcemia is caused by taking excessive amounts of vitamin D, but it also can be caused by excess calcium supplementation, cancer, an overactive parathyroid gland and use of certain medications.
Treatment
Consult your doctor if you exhibit signs and symptoms of vitamin D toxicity. In most cases, treatment for vitamin D overdose involves supplement cessation, notes MedlinePlus. You may need to limit your calcium intake as well, and your doctor may prescribe certain drugs. Severe cases of vitamin D toxicity may require hospitalization and more extensive treatment of hypercalcemia. You may need intravenous fluids to treat dehydration, or diuretics to remove the excess calcium from your body. Hemodialysis may be needed if kidney function is impaired and no other treatment works.
Dosage
Oregon State University's Linus Pauling Institute indicates that most cases of hypercalcemia occur when individuals take more than 50,000 IUs of daily vitamin D. Hypervitaminosis D is rare in healthy adults who take less than 10,000 IUs. Mayo Clinic's Zeratsky states that vitamin D toxicity may be more likely at lower doses if you have kidney or liver problems or take certain diuretics. The Institute of Medicine established a safe upper limit for vitamin D of 4,000 IU a day, or 100 mcg, for adults. Children age 8 and younger can tolerate 3,000 IU vitamin D a day and less.
Tips
Doctors prescribe vitamin D supplements for therapeutic purposes. For example, children with rickets may be treated with supplemental vitamin D, as may adults with osteomalacia. Supplemental vitamin D may also be used to treat psoriasis, hypoparathyroidism, hyperparathyroidism and a rare genetic disorder that inhibits vitamin D metabolism. Vitamin D supplements are one way to make sure that you get the requisite amount of this essential nutrient. However, don't self-treat with large amounts of this vitamin. If you suspect you have a medical condition caused by vitamin D deficiency, consult with your physician.
References
- NIH.gov: Hypervitaminosis D; November 2009
- MayoClinic.com: Vitamin D Toxicity -- What if You Get Too Much?; Katherine Zeratsky, R.D., L.D.; December 2010
- Linus Pauling Institute: Vitamin D; December 2010
- University of Maryland Medical Center: Hypervitaminosis D - Overview
- MayoClinic.com: Hypercalcemia -- Treatment and Drugs; May 29, 2009
- Colorado State University Extension; Fat-Soluble Vitamins; J. Anderson, L. Young (August 2008)
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