Hypervitaminosis D
| Hypervitaminosis D | |
|---|---|
 |
|
| Cholecalciferol (shown above) and ergocalciferol are the two major forms of Vitamin D. | |
| Classification and external resources | |
| Specialty | endocrinology |
| ICD-10 | E67.3 |
| ICD-9-CM | 278.4 |
| DiseasesDB | 13939 |
| MedlinePlus | 001594 |
Hypervitaminosis D is a state of vitamin D toxicity. The normal range for blood concentration is 30.0 to 74.0 nanograms per milliliter (ng/mL).
Symptoms of vitamin D toxicity may include the following:
An excess of vitamin D causes abnormally high blood concentrations of calcium, which can cause overcalcification of the bones, soft tissues, heart and kidneys. In addition, hypertension can result.
Hypervitaminosis D symptoms appear several months after excessive doses of vitamin D are administered. In almost every case, a low-calcium diet combined with corticosteroid drugs will allow for a full recovery within a month. Vitamin D toxicity is closely related to a depletion of Vitamin K and that repletion of Vitamin K allows individuals to supplement with higher doses of Vitamin D without the negative calcium-related side effects.
The U.S Institute of Medicine has established a Tolerable Upper Intake Level (UIL) to protect against vitamin D toxicity. These levels in microgram (mcg or µg) and International Units (IU) for male and female are:
(Conversion : 1 µg = 40 IU and 0.025 µg = 1 IU.)
The recommended daily allowance is 15 µg/d (600 IU per day). Overdose has been observed at 1,925 µg/d (77,000 IU per day). Acute overdose requires between 15,000 µg/d (600,000 IU per day) and 42,000 µg/d (1,680,000 IU per day) over a period of several days to months, with a safe intake level being 250 µg/d (10,000 IU per day). Foods contain low levels, and have not been known to cause overdose.
Based on risk assessment, a safe upper intake level of 250 µg (10,000 IU) per day in healthy adult has been suggested.
Excessive exposure to sunlight poses no risk in vitamin D toxicity through overproduction of vitamin D precursor, cholecalciferol, regulating vitamin D production. During ultraviolet exposure, the concentration of vitamin D precursors produced in the skin reach an equilibrium, and any further vitamin D that is produced is degraded. This process is less efficient with increased melanin pigmentation in the skin. Endogenous production with full body exposure to sunlight is comparable to taking an oral dose between 250 µg and 625 µg (10,000 IU and 25,000 IU) per day.
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