A couple of scare stories about tanning beds potentially causing vitamin D toxicity emerged today, with headlines like ‘A Case of Vitamin D ‘Overdose’ From Tanning Bed Use‘ and ‘Can tanning beds cause vitamin D toxicity?‘. So are we putting ourselves at risk from tanning salons?
Hypervitaminosis D, or vitamin D toxicity, leads to various symptoms such as
- Decreased appetite
- Muscle weakness
- Metastatic calcification of the soft tissues
The last of these, hypercalcemia, is the primary problem. Hypercalcemia, which means elevated calcium levels in the blood, leads to calcification of the arteries and other soft tissue potentially increasing the risk of heart attacks, kidney damage and kidney stones.
So which of these symptoms was she suffering from? This is how the Boston globe reported it:
In a case report published Monday in the Annals of Internal Medicine, two physicians from Saint Vincent Hospital in Worcester described a 26-year-old woman who they treated for excessively high vitamin D levels detected during a routine blood test. At first they couldn’t pinpoint the cause since she didn’t take vitamin D supplements and wasn’t a big milk drinker. She did, however, go to tanning salon at least three times a week for six months. The ultraviolet radiation from the UV lamps caused her skin to produce vitamin D in excessive amounts to the point that she had a dangerously high level.
Firstly, note that this was only spotted from a routine blood test, not because she was suffering from any of the symptoms of toxicity. In fact, Every Day Health actually reported that she
was referred to the endocrinology clinic for asymptomatic vitamin D toxicity
There is no such thing as ‘asymptomatic vitamin D toxicity'; either she is suffering from hypercalcemia or she isn’t.
Although I haven’t seen the original report, one commenter on the article added that she had a blood serum level of 25(OH)D of 339 nmol/L (around 136 ng/mL). 25(OH)D is the most reliable indicator of vitamin D levels in the body. Although higher than the currently regarded optimum level of 50-60 ng/mL, this is still well below the 200 ng/mL usually considered to be potentially toxic.
So what this story is really about is a woman who had high vitamin D blood levels from a tanning bed that caused no apparent harm, and were well below potentially toxic levels.
There hasn’t yet been a confirmed case of sunbathing or tanning beds causing the body to reach toxic levels of vitamin D, and that remains the case.