Hypervitaminosis D
Vitamin D toxicityHypervitaminosis D is a condition that occurs after taking very high doses of vitamin D.
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Causes
The cause is excess intake of vitamin D. The doses need to be very high, far above what most health care providers normally prescribe.
There has been a lot of confusion about vitamin D supplementation. The recommended daily allowance (RDA) for vitamin D is between 400 and 800 IU/day, according to age and pregnancy status. Higher doses may be needed for some people, such as those with vitamin D deficiency, hypoparathyroidism, and other conditions. However, most people do not need more than 2,000 IU of vitamin D a day.
For most people, vitamin D toxicity only occurs with vitamin D doses above 10,000 IU per day.
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Symptoms
An excess of vitamin D can cause an abnormally high level of calcium in the blood (hypercalcemia). This can severely damage the kidneys, soft tissues, and bones over time.
The symptoms include:
- Constipation
- Decreased appetite (anorexia)
- Dehydration
- Fatigue and confusion
- Frequent urination
- Irritability
- Muscle weakness
- Vomiting
- Excessive thirst (polydipsia)
- High blood pressure
- Passing large amounts of urine (polyuria)
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Exams and Tests
Your provider will examine you and ask about your symptoms.
Tests that may be ordered include:
- Calcium level in the blood
- Calcium level in the urine
- 25-hydroxy vitamin D level
- 1,25-dihydroxy vitamin D level
- Serum phosphorus level
- X-ray of the bone
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Treatment
Your provider will likely tell you to stop taking vitamin D. In severe cases, other treatment may be needed.
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Outlook (Prognosis)
Recovery is expected, but permanent kidney damage can occur.
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Possible Complications
Health problems that can result from taking too much vitamin D over a long time include:
- Dehydration
- Hypercalcemia
- Kidney damage
- Kidney stones
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When to Contact a Medical Professional
Contact your provider if:
- You or your child shows symptoms of hypervitaminosis D and has been taking more vitamin D than the RDA
- You or your child shows symptoms and has been taking a prescription or over-the-counter form of vitamin D
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Prevention
To prevent this condition, pay careful attention to the correct vitamin D dose. Use vitamin D supplements from reliable licensed sources.
Many combination vitamin supplements contain vitamin D, so check the labels of all the supplements you are taking for vitamin D content.
References
Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Melmed S, Auchus, RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 29.
Greenbaum LA. Vitamin D deficiency (rickets) and excess. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 64.
National Institutes of Health Office of Dietary Supplements website. Vitamin D fact sheet for health professionals. ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/. Updated September 18, 2023. Accessed January 19, 2024.