Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014


Excess blood calcium / Calcium intoxication

©1996 Melissa Kaplan


The causes of hypercalcemia or excessive blood levels of calcium are fairly well established in animals as well as man. In reptiles, they may include:

  • Excessive absorption via the GI tract

  • Parathyroid hormone excess (often due to malignancies in the gland)

  • Malignancies with bone involvement

  • Hyperthyroidism

  • Animal protein ingestion in herbivorous lizards

  • Vitamin D and vitamin A intoxication (vitamin D in high doses produces excessive bone resorption as well as increased intestinal absorption of calcium.

Hypercalcemia in turn causes bone defects, cardiac changes, shock, renal hypertension and failure and death at especially high levels. Bone defects and cardiac involvement may not be apparent to the iguana owner until the condition is well advanced. Once shock and renal failure set it, it is usually too late.

The best way to avoid hypercalcemia is to not go overboard on vitamin supplementation, including supplementing D3 through oral vitamins. The best way to provide D3 is through regular access to natural, unfiltered sunlight (that is, sun not shining through glass, plastic or dense screen). When regular exposure to direct sun is not possible, then regular exposure to UVB-producing fluorescent lights, with the reptile no more than 18 inches away (and ideally within 12 inches) from the unfiltered tube is required. Finally, if you have an herbivorous lizard such as Giant Green Iguanas (Iguana iguana), desert iguanas (Dipsosaurus), dab lizards (Uromastyx), and prehensile-tailed skinks (Corusia), do not feed them any animal protein.

For information on lighting, heating and ultraviolet B, please see the lighting/heating and UV articles on the Captive Environment page.

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