The co-authors of Invasion of the Prostate Snatchers, blog alternate posts weekly. We invite you to post your comments.

Tuesday, May 28, 2013

Osteoporosis Basics for Men


Osteoporosis is the medical term for “weakened bones” resulting from the slow leaching of calcium over time. Osteoporosis is incorrectly thought to happen only in females. However, one-third of hip fractures occur in men and are associated with higher mortality rates in men with prostate cancer. Calcium loss is a silent process until a fracture suddenly occurs. Common fracture sites are spine, rib, wrist, and hip. Compression fractures of the spine can be quite painful and result in loss of height with forward curvature of the spine.  

Cause of Osteoporosis

Just as there is a link between lack of estrogen and osteoporosis in women, studies show that there is also a relationship between a lack of testosterone and osteoporosis in men. Other causes of osteoporosis are thyroid or parathyroid hyperactivity, excessive alcohol, cortisone, lack of exercise, low vitamin D and low calcium intake. Osteoporotic fractures also occur more frequently in men taking testosterone inactivating pharmaceuticals (TIP).

Detecting Osteoporosis
Osteoporosis, when it is diagnosed at an early stage, is easier to treat. Unfortunately, the most common scanning technique for diagnosing osteoporosis, the DEXA scan—grossly underestimates the degree of bone mineral loss from the spine in men. Why? Because almost all men over fifty have calcium deposition in the ligaments surrounding the spine. When the DEXA is used to measure bone density, the excess calcium in the ligaments causes an incorrectly “normal” bone density reading.

Fortunately there is a better technique called QCT that measures bone mineral density in the center of the vertebral column. Awareness of the DEXA scans' limitations in men is under appreciated by many physicians even though these limitations have been well documented in a study from Massachusetts General Hospital. In this study 41 men underwent both DEXA and QCT scanning. QCT detected osteoporosis in 26 of the men (63%) but DEXA only diagnosed it in two (5%).

Preventing Osteoporosis
Osteoporosis treatment begins with an exercise program. Supplementation with calcium and vitamin D should also be considered routine. We recommend 500 mg of calcium at bedtime and a starting dose of 1,000 units of Vitamin D. Blood levels of vitamin D should be checked and oral intake of vitamin D adjusted accordingly.  Studies show that using TIP intermittently (compared to continuous TIP) results in less bone loss. Treatment with bisphosphonates or denosumab (see below) can prevent TIP-induced bone loss.

Osteoporosis Medications
Osteoporosis can be reversed with bisphosphonates or denosumab. Normal bone metabolism is a balance between the rate of bone breakdown and the formation of new bone. Osteoporosis occurs when the formation of new bone lags behind the rate of bone breakdown. Bisphosphonates and denosumab function by slowing the rate of bone breakdown, allowing the osteoblasts, the cells that form new bone, to increase the net amount of bone matrix.

Oral Medications: Boniva, Actonel and Fosamax
Bisphosphonates come in both oral and intravenous forms. Absorption into the blood of oral forms is enhanced when they are administered with an empty stomach. The most common side effect from oral bisphosphonates is stomach or esophageal irritation which can be minimized by maintaining an erect position for an hour after taking the drug.

Intravenous Bisphosphonates: Zometa (zolendric acid)
Intravenous administration of Zometa has the advantage of bypassing the stomach thus avoiding concerns about stomach irritation. Also with the intravenous approach 100% of the drug gets into the system as compared to the oral preparations that are only 1-2% absorbed. The most common side effect from Zometa is a brief flu-like muscle soreness lasting a day or so. These symptoms do not usually recur on subsequent infusions. For the treatment of osteoporosis the infusions are repeated every three to six months.

Denosumab Injections: Prolia and Xgeva
Like Zometa, denosumab inhibits the osteoclasts, but by a different mechanism.  Denosumab is marketed in two strengths for injection. A half-dose shot called Prolia is administered every 6 months for osteoporosis.  A full dose shot called Xgeva is given monthly for cancer metastasis to the bone.

Medication Induced Jaw Problems: Osteonecrosis
Zometa and denosumab and to a much lesser degree, oral bisphosphonates can rarely induce damage to the jaw, a condition termed osteonecrosis.  The risk of developing osteonecrosis is much higher when a tooth is extracted. When osteonecrosis occurs, the gum tissue recedes leaving exposed bone which is susceptible to recurrent infections. The risk of osteonecrosis becomes higher as the lifelong cumulative medication dosage increases. In my experience, osteonecrosis almost always reverses, albeit slowly, after the medication is stopped.
Bone Metastases
Zometa and denosumab are also FDA approved to treat cancer that has metastasized to bone. Their anticancer effect is believed to occur because by inhibiting bone breakdown, cancer cell access to the growth factors and cytokines that are normally locked up in the bone matrix is blocked. So these medications that inhibit bone turnover by stopping osteoclast activity not only help osteoporosis but also help to prevent bone metastases from progressing.

Final thoughts
Eventually some degree of osteoporosis occurs in most men as they age.  Regular exercise, calcium and vitamin D help delay bone loss.  Bone density screening in men should probably begin when they are in their 60s, so the condition can be detected early.  Bone density augmentation with denosumab or bisphosphonates seems to be more effective when osteoporosis is not too severe at the start of therapy.   

1 comment:

Susan Yoga said...

Osteoporosis is a disease in which bones become fragile and more likely to fracture.Most of them dont take care until they find more pain or difficult. Osteoporosis are very dangerous it should be taken care of at initial stage.