The two hypervitaminosis D patients had been intoxicated as a result of supplementation by their physicians. Both had undergone surgery on their necks for cancer and as can happen in such surgery the parathyroid glands were damaged. This resulted in a low serum calcium causing irritability, and possibly uncontrollable muscle spasm. At the time, (late 1970’s) the only available treatment was supplemental oral calcium and large doses of Vitamin D.
What the treating physicians did not realize, was that the parathyroid gland damage is often transient and may recover in several days. Both of these patients received three weeks of high dose calcium gluconate orally, and Vitamin D. (ergocalciferol or D2) Probably 2-3 grams daily. Activation of Vitamin D to 25 hydroxy form is not rate limited in the liver and is totally dependent on how much precursor is available. So both of these patients must have had massively elevated serum levels, but that test was not available at the time.
Both developed coma, renal failure and marked elevation of their serum calcium levels. They were successfully treated with IV fluids, diuretics and steroids, but it took several weeks for them to wake up and recover kidney function. One of them suffered from kidney stones for years thereafter.
You asked why sun worshipers don’t suffer the same problem. It’s probably because conversion of 7-dehydrocholesterol to D3 in the skin is rate limited by the amount of UV exposure and as the skin tans, progressively less and less UV light penetrates deeply enough to convert the 7-dhc to D3.
I’m not a Vitamin D expert by any stretch. I haven’t treated either deficiency or intoxication in years.
2 - 3 grams? Yowser! The conversion of grams to IU varies with the vitamin type but I'm reading that 2.5 micrograms equals 100 IU for vitamin D. If that's so, and my math is correct, they were getting some 100 million IU daily.
Many thanks for your response; I am very interested in this. I think I can see where your patients got into trouble. Not only were they taking D2 instead of D3, but 1 mg (milligram) of D = 40,000 IU. I can certainly see where 2-3 grams would them out! I have become convinced that up to 10,000 IU/Day is not harmful but beneficial. I’ve been on 6000 for years; If I go down from toxicity, I’ll post from my death bed. The conversion of D from IU to mg is difficult. Here are my sources:
http://wiki.answers.com/Q/How_do_you_convert_vitamin_d_iu_to_mg
http://riteaid.naturemade.com/faq/faq.asp?s=108#505
Fair enough; but what then do you say of people who don't have damaged parathyroids to come back on line; who are taking D3, not D2; and are taking 2000 IU a day (in other words, 50 μg a day, not 2-3 grams)?
Not quite the same thing...? Cheers!