A 67-year-old woman comes to the office suffering from polymyalgia rheumatica. She was diagnosed a year ago and has had to take prednisone at supraphysiologic doses to control her symptoms. The patient has no other medical conditions. She gets enough calcium and vitamin D through her diet and supplements. The patient does not use tobacco or alcohol. The physical examination is unremarkable. Serum creatinine, 25-hydroxyvitamin D, and calcium levels are normal, according to laboratory results. When compared to her bone density at age 65, her bone density as measured by dual x-ray absorptiometry (DX A) shows a significant decline. Which of the following is most likely contributing to this patient's bone loss?

Question

A 67-year-old woman comes to the office suffering from polymyalgia rheumatica. She was diagnosed a year ago and has had to take prednisone at supraphysiologic doses to control her symptoms. The patient has no other medical conditions. She gets enough calcium and vitamin D through her diet and supplements. The patient does not use tobacco or alcohol. The physical examination is unremarkable. Serum creatinine, 25-hydroxyvitamin D, and calcium levels are normal, according to laboratory results. When compared to her bone density at age 65, her bone density as measured by dual x-ray absorptiometry (DX A) shows a significant decline. Which of the following is most likely contributing to this patient's bone loss?

Quizplus · Accepted Answer

Eductional Objective: Chronic or recurrent glucocorticoid (eg, prednisone) use, as required in polymyalgia rheumatica patients, is associated with a higher risk of osteoporosis. Glucocorticoids hasten the development of osteoporosis through a variety of mechanisms:
Reduced osteoblast effect: Glucocorticoids inhibit osteoblast precursor cell proliferation and differentiation. They also cause an increase in apoptosis in mature osteoblasts.
Increased osteoclast effect: The receptor activator of nuclear factor kappa B (RANK)/RANK-ligand promotes osteoclast differentiation and activity, which is inhibited by osteoprotegerin, which acts as a decoy receptor. Glucocorticoids increase RANK and RANK-ligand expression  while decreasing osteoprotegerin expression , resulting in increased bone resorption.
Renal and intestinal calcium wasting: Because glucocorticoids inhibit intestinal calcium absorption and renal calcium reabsorption, increased calcium release from bone is required to maintain calcium homeostasis.

A 67-Year-Old Woman Comes to the Office Suffering from Polymyalgia Rheumatica