What You Need to Know About (Steroid Drug) Corticosteroid-Induced Osteoporosis
From Carol & Richard Eustice

READ COMPLETE ARTICLE

Corticosteroid-Induced Osteoporosis is Both Preventable and Treatable
Corticosteroids are one type of steroid medication. Sometimes the term "steroid" is used interchangeably with "corticosteroid".

What's The Difference Between Anabolic Steroids & Corticosteroids?

According to the ACR, more than 30 million Americans may be affected by diseases commonly treated with corticosteroids. Steroids such as prednisone, are used as therapy for many inflammatory and autoimmune diseases, such as:

asthma
rheumatoid arthritis
lupus
inflammatory bowel disease

They are also used to treat many allergic conditions. While steroids are generally effective in treating such ailments, they are also the most common cause of drug-induced osteoporosis.

Corticosteroids & Bone Remodeling

Corticosteroids affect calcium and bone metabolism in many ways.

steroids decrease the amount of calcium absorbed by the intestine
steroids increase calcium excretion through the kidneys

These two factors combine to produce a decline in the circulating ionized calcium concentration. This triggers the parathyroid glands to increase the secretion of parathyroid hormone (PTH), a condition known as secondary hyperparathyroidism. Elevated PTH levels result in increased bone breakdown, as the body attempts to rectify low circulating calcium levels by releasing calcium from the bones into the blood.

Corticosteroids can also decrease the levels of the sex hormones:

estrogen (in women)
testosterone (in men)

The resulting decreases are associated with increased bone loss.

Corticosteroids also cause muscle weakness, which may lead to inactivity and additional bone loss. Another major effect of corticosteroids is that they can impact bone directly by suppressing bone formation (osteoblastic) activity.

Patterns of Bone Loss

There are two types of bone tissue: cortical and trabecular.

Cortical bone forms the outer shell of bone and comprises 80% of the skeleton
Trabecular bone (the remaining 20%) is found inside the bone

Each bone in the skeleton contains both types of bone, but their proportions vary. Corticosteroids primarily cause bone loss in those areas of the skeleton that are rich in trabecular bone, such as the spine.

Dose and Duration

Bone loss occurs most rapidly in the first 6 to 12 months of therapy and is dependent on both:

dose
duration

Other risk factors for osteoporosis may have an additive effect on bone loss, such as:

age
gender
underlying disease

For example, elderly men on steroids may experience even greater bone loss and risk for fracture than middle aged men. ACR estimates that without prevention measures, an estimated 25% of individuals on long-term corticosteroids will experience a fracture.

The dose of corticosteroids is a strong predictor of fracture risk. While it is not clear whether there is a low-dose threshold below which bone loss does not occur, recent studies have found inhaled steroids to have little to no effect on bone density when administered in standard doses and apart from systemic steroids...

...Osteoporosis prevention measures should begin early, ideally at the onset of corticosteroid therapy. Experts recommend using the lowest dose of steroid for the shortest period of time possible and, when feasible, inhaled or topical corticosteroids should be utilized.

Source: Glucocorticoid-Induced Osteoporosis, NIH ORBD~NRC, 12/2000