Vitamin D toxicity causes high levels of calcium in the blood.
People with vitamin D toxicity may lose their appetite, feel nauseated, vomit, and feel weak and nervous.
Doctors diagnose the toxicity by measuring levels of calcium and vitamin D in the blood.
Treatment involves stopping vitamin D supplements and giving the person fluids and sometimes drugs.
(See also Overview of Vitamins Overview of Vitamins Vitamins are a vital part of a healthy diet. The recommended dietary allowance (RDA)—the amount most healthy people need each day to remain healthy—has been determined for most vitamins. A safe... read more .)
Taking very high daily doses of vitamin D—for example, 60 to 100 or more times the recommended daily allowance (RDA)—over several months can cause toxicity and a high calcium level in the blood (hypercalcemia Hypercalcemia (High Level of Calcium in the Blood) In hypercalcemia, the level of calcium in blood is too high. A high calcium level may result from a problem with the parathyroid glands, as well as from diet, cancer, or disorders affecting... read more ). Levels of calcium become high because when levels of vitamin D are high, the following occur:
More bone is broken down than is reformed. (Normally, bones are continuously broken down and reformed—in a process called remodeling—to adjust to the changing demands placed on them.) As a result, calcium is released from the bone into the bloodstream.
More calcium is absorbed from food in the intestine.
Vitamin D may be used to treat psoriasis Psoriasis Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin. A problem with the immune... read more , hypoparathyroidism Hypoparathyroidism Hypoparathyroidism is a deficiency of parathyroid hormone (PTH) often caused by an autoimmune disorder, treatment-related damage to the parathyroid glands, or removal of the glands during surgery... read more , and renal osteodystrophy Chronic Kidney Disease Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood. Major causes are diabetes and high blood pressure... read more . Vitamin D has not been proven to prevent leukemia and breast, prostate, colon, or other cancers. Vitamin D supplementation does not effectively treat or prevent depression or cardiovascular disease, nor does it prevent fractures or falls. Some evidence, however, suggests that taking the combined recommended daily allowance of both vitamin D and calcium reduces the risk of fractures in people who are vitamin D deficient.
Symptoms of Vitamin D Excess
Early symptoms of vitamin D toxicity are loss of appetite, nausea, and vomiting, followed by weakness, nervousness, and high blood pressure.
Because the calcium level is high, calcium may be deposited throughout the body, particularly in the kidneys, blood vessels, lungs, and heart. The kidneys may be permanently damaged and malfunction, resulting in kidney failure.
Diagnosis of Vitamin D Excess
Vitamin D excess is usually diagnosed when blood tests detect a high calcium level in a person who takes high doses of vitamin D. Doctors also measure the level of vitamin D in the blood.
Treatment of Vitamin D Excess
Stopping vitamin D supplements
Fluids given intravenously
Treatment of vitamin D toxicity involves stopping vitamin D supplements to offset the effects of a high calcium level in the blood. Fluids are given intravenously as needed.
Drugs, such as corticosteroids Corticosteroids: Uses and Side Effects or bisphosphonates Drugs Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more , are given to suppress the release of calcium from the bones.