You may think that taking vitamin D supplements is good for you, especially if you wisely use lots of sunscreen when you're outdoors, or you don't eat a lot of dairy foods. But too much of a good thing can be bad for you, and that applies to vitamin D, as well. Overdosing on vitamin D supplements can cause a condition called hypervitaminosis D, which can cause you to urinate excessively. You can also develop a related condition, called hypercalcemia.
Hypervitaminosis D
Taking excessive amounts of vitamin D supplements can cause hypervitaminosis D, also known as vitamin D toxicity. Hypervitaminosis D, in turn, can cause polyuria, excessive urination, and nocturia. Nocturia is the need to urinate excessively at night. Another symptom, polydipsia, can exacerbate the problem. Polydipsia is excessive thirst. Drink more water, and you want to urinate even more frequently.
Hypervitaminosis D can also affect your central nervous system, soft tissues, bones and gastrointestinal tract, causing a range of symptoms. Those symptoms can include high blood pressure, nausea, constipation and weight loss.
Hypercalcemia
The main consequence of hypervitaminosis D is hypercalcemia, which is a buildup of calcium in the blood. Vitamin D is integral to the absorption of calcium. More vitamin D in the blood leads to more calcium in the blood. Polyuria is a symptom of hypercalcemia, as well as hypervitaminosis D. Additional symptoms of hypercalcemia include weakness, constipation, vomiting, weight loss, reduced appetite and heart rhythm abnormalities.
Supplement Intakes
You do not run the risk of developing hypervitaminosis D if you take a couple of extra supplements by accident. You need to take enough to raise the level of vitamin D in your blood to toxic levels. This means excessive vitamin D for a while. The Merck Manual warns that taking 50,000 IU per day can cause toxicity after several months. However, even taking just over 4,000 IU per day of vitamin D can increase your risk of adverse effects, according to the Mayo Clinic website. For most adults younger than 70, 600 IU, or 15 mcg, daily is sufficient. If you're older than 70, take 800 IU, or 20 mcg daily. If you are severely deficient in vitamin D, your doctor may prescribe a megadose, which you will take for several weeks. Notify your doctor if you experience any unusual symptoms while you're taking this megadose.
Polyuria and Nocturia
Although excessive urination can be a symptom of taking too much vitamin D, it can also have other causes. Drinking a lot of fluids, especially alcoholic or caffeinated beverages, can be an obvious cause of polyuria. Other potential causes include diabetes, certain medications, kidney failure and sickle-cell anemia. A bladder obstruction or infection can also cause excessive urination.
References
- Drugs.com: Vitamin D Ergocalciferol
- Medline Plus: Urination: Excessive Volume
- The Merck Manual: Vitamin D
- Mayo Clinic; What is Vitamin D Toxicity, and Should I Worry About it Since I Take Supplements; Katherine Zeratsky, R.D., L.D.; August 2011
- Cleveland Clinic: Nocturia
- The New York Times Health Guide: Thirst: Excessive
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