Steroids are frequently prescribed by doctors for a variety of clinical disorders such as asthma, low back pain, rheumatoid arthritis, inflammatory bowel disease, MS, and Systemic Lupus Erythematosus. Quite often, patients stay on steroids for a long duration. And end up experiencing serious side-effects, which are sometimes even worse than the original disease, such as avascular necrosis of hip or shoulder, serious infections, diabetes, high blood pressure, glaucoma, macular edema, proximal myopathy, severe osteoporosis which can lead to fragility fractures.
Steroids and Vitamin D
While there are several mechanisms how stereotypes can cause their side-effects, vitamin D deficiency appears to be a major pathway. Steroids antagonize the beneficial effects of vitamin D. For example, in bone, vitamin D enhancements bone formation by stimulating osteoblasts, increasing calcium absorption from intestines and preventing secondary hyperparathyroidism. Steroids do exactly the opposite: they have inhibitory effect on osteoblasts, decrease calcium absorption from intestines, increase calcium wasting from kidneys and cause secondary hyperparathyroidism. In this way steroids cause a rapid bone loss (osteoporosis).
In addition, Vitamin D boosts up immune system whereas steroids suppress it. Vitamin D reduces blood pressure whereas steroids increase it. Vitamin D reduces insulin resistance whereas steroids increase it. Vitamin D builds up muscles whereas steroids cause myopathy.
It is pretty obvious that steroids antagonize the effects of vitamin D.
What is the mechanism?
One mechanism is that steroids alter the vitamin D receptor. Steroids also cause obesity, and consequentially, decrease the available circulating vitamin D. There could be other mechanisms as well.
From a clinical point, steroids rob you off the beneficial effects of Hormone D in as little as 5 days. Therefore, I recommend my patients to double the dose of vitamin D while they go on steroids, and pay close attention to their serum and urine calcium. Salt restriction to 3 grams per day and use of a thiazide diuretic can reduce the urine calcium wasting.
"Prevention is better than cure" is your best bet when it comes to steroid-induced osteoporosis because no drug available currently can effectively treat this type of osteoporosis.