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Newsletter: Vitamin D toxicity quiz

Posted on: December 1, 2003   by  John Cannell, MD


This edition is a short quiz to test your knowledge of vitamin D toxicity. In a few days we will repeat the questions and discuss the answers.

We all know cholecalciferol is a fat soluble vitamin occurring naturally in the body as a result of UVB sunlight striking the skin. It can also cause toxicity in overdose by raising serum calcium and causing widespread deposition of calcium in body tissues (calcinosis). Like Coumadin, toxic amounts of cholecalciferol are occasionally used as a rodent poison. Given together with nicotine, large doses of vitamin D are also used to induce rapid hardening of the arteries to create animal disease models of arteriosclerosis.

However, exactly how much cholecalciferol would we have to take to cause toxicity? In other words, how toxic is vitamin D and how does it compare to other substances in the home? Test your knowledge.

1. If an otherwise healthy adult tried to kill himself by taking an entire bottle (250 capsules) of 1,000 IU cholecalciferol, which of the following would happen?

A. The person would die within 24 hours from severe hypercalcemia and widespread calcinosis.

B. If the person received intensive treatment for hypercalcemia he may survive.

C. Hypercalcemia would be severe but require only supportive treatment.

D. Such doses are called “Stoss” therapy and are occasionally used therapeutically although they do not replicate normal physiology. As most Americans are vitamin D deficient, such a one-time dose would probably be a health benefit for the majority of Americans.

2. Acute poisoning leading to rapid death from ingestion of vitamin D capsules (successful suicide attempt):

A. Has frequently been reported in the literature.

B. Has occasionally been reported in the literature

C. Has never been reported in the literature.

3. True of False: Water has a higher (safer) therapeutic index (the median lethal dose divided by the median effective dose) than cholecalciferol.

A. True

B. False

C. About the same

4. If a person totally avoided the sun and regularly took two standard multivitamins a day for several years, each containing 400 IU of ergocalciferol, as his sole source of vitamin D, he would:

A. Rapidly become vitamin D toxic and require medical attention for symptoms of hypercalcemia.

B. Slowly become vitamin D toxic and eventually become symptomatic.

C. Slowly develop hypervitaminosis D but remain asymptomatic.

D. Obtain a healthful vitamin D blood level.

E. Inexorably become vitamin D deficient.

5. Of the three medications listed below, which is the safest in overdose?

A. Vitamin D (250 of the 1,000 IU capsules)

B. Aspirin (250 of the 325 mg tablets)

C. Tylenol (250 of the 500 mg tablets)

6. Which drug has the highest (safest) therapeutic index?

A. Depakote

B. Lithium

C. Coumadin

D. Dilantin

E. Synthroid

F. Theophylline

G. Cholecalciferol

7. In 1997, Adams and Lee wrote a widely publicized paper about vitamin D toxicity published in Annals of Internal Medicine. The paper was accompanied by a stern editorial warning of the dangers of vitamin D written by Marriot of the International Institute of Health. The three authors:

A. Correctly diagnosed all five of the patients

B. Were thanked by nationally acclaimed vitamin D scientists for their contributions to understanding vitamin D toxicity.

C. Showed frightening ignorance about vitamin D toxicity and appeared not to know the difference between the two standard deviation upper limit of a Gaussian distribution and levels known to reflect vitamin D toxicity.

8. By sunbathing for a few minutes in the noonday summer sun, once can easily obtain five times the vitamin D toxicity warning (lowest observed adverse effects level or LOAEL) of the institute of medicine’s food and nutrition board.

A. True

B. False

9. If humans are twice as sensitive as the most sensitive mammal tested (male rats), then a 110 lb. human would have to inject 88,000 capsules (352 bottles containing 250 of the 1,000 IU capsules) of cholecalciferol in order to have a 50% chance of dying (LD50) from an acute overdose.

A. True

B. False

10. As most American blacks suffer from vitamin D deficiency, some black activists feel unwarranted scare techniques about vitamin D toxicity may be racially motivated. That is, racists may be intentionally repeating and promulgating vitamin D toxicity scares in order to prevent relevant government agencies from dealing with the problem of widespread vitamin D deficiency in the black community.

A. True

B. False

11. In the most recent case of vitamin D toxicity described in the literature, a man recovered uneventfully after taking a health supplement every day for two years that contained more than 156 of the 1,000 IU cholecalciferol capsules.

A. True

B. False

12. One of the world’s foremost authorities on vitamin D metabolism and physiology recently said, “Worrying about vitamin D toxicity is like worrying about drowning when you are dying of thirst.”

A. True

B. False

The next newsletter will discuss the answers to these questions while the one after that will discuss vitamin D, mood and major depression.

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