In healthy older women, an interval of 23 months for repeat BMD assessment makes little sense. For women who have excellent initial T-scores, clinicians can lengthen this interval significantly.
However, strict reliance on the T-score isn’t the best way to predict a woman’s fracture risk or determine when pharmacologic intervention is warranted. Rather, yearly assessment using a tool such as FRAX should become the standard of care.
Miller PD. Unrecognized and unappreciated secondary causes of osteoporosis. Endocrinol Metab Clin North Am. 2012;41(3):613–628.
The fractures traditionally associated with osteoporosis involve the hip and vertebrae, although low-trauma fractures of the humerus, forearm, femur shaft, tibia, and fibula are also associated with a high risk of future fracture in untreated women.
Once a clinician is confident that a patient has osteoporosis, the question is whether the diagnosis is postmenopausal osteoporosis—or some other form of the disease. Although estrogen deficiency is the most common cause of osteoporosis in postmenopausal women, many other conditions may accompany estrogen deficiency and contribute to impaired bone strength in this population.
Among the culprits are some conditions that are not often encountered in the average gynecologic practice: monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma, celiac disease, Crohn’s disease, and other inflammatory bowel diseases. In addition, bariatric surgery, eating disorders, primary hyperparathyroidism, and a number of medications have been implicated in BMD loss or increased risk of fracture, or both. Among the problematic drugs of particular interest to us as gynecologists are aromatase inhibitors, depot medroxyprogesterone acetate, proton pump inhibitors, and gonadotropin-releasing hormone (GnRH) agonists.
Other medications that can affect BMD are glucocorticoids, unfractionated heparin, selective serotonin reuptake inhibitors, excessive amounts of thyroid replacement agents, and some antiseizure medications.
If you suspect a secondary cause of osteoporosis, be prepared to perform a basic workup that includes:
- a careful history and physical examination
- complete blood count
- a chemistry profile, including serum calcium, phosphorous, electrolytes, alkaline phosphatase, and creatinine.
In addition, measurement of 25-hydroxy vitamin D and thyroid-stimulating hormone (TSH) may be helpful, as may serum protein electrophoresis.
Patients who have clinical or laboratory abnormalities suggestive of a secondary cause of osteoporosis are usually referred to a metabolic bone specialist (endocrinology or rheumatology).
When a patient has any clinical history that suggests a secondary cause of bone loss other than menopause-related estrogen deficiency, simple laboratory tests are appropriate and may uncover a condition that necessitates referral to a metabolic bone expert.
Guglielmi G, Rossini M, Nicolosi MG, Tagno A, Lentini G, de Terlizzi F. Three-year prospective study on fracture risk in postmenopausal women by quantitative ultrasound at the phalanges [published online ahead of print August 15, 2012]. J Clin Densitom. doi:10.1016 /j.jocd.2012.07.006.
Chan MY, Nguyen ND, Center JR, Eisman JA, Nguyen TV. Quantitative ultrasound and fracture risk prediction in non-osteoporotic men and women as defined by WHO criteria [published online ahead of print August 10, 2012]. Osteoporos Int. doi:10.1007/s00198-012 -2001-2.
I became interested in bone health through my longstanding interest in ultrasound, when a manufacturer asked me to evaluate equipment designed to assess bone density of the heel through quantitative ultrasound (QUS). This modality is not the diagnostic imaging we are familiar with in obstetrics and gynecology. In QUS, the homogeneity of healthy bone promotes sound transmission, whereas the voids and discontinuity of osteoporotic bone impede it. Therefore, normal bone has a faster speed of sound than less healthy bone. The other important quantitative measure is broadband ultrasound attenuation (BUA). Healthy bone is dense and absorbs and scatters sound to a greater extent than osteoporotic bone does.
Two trials of QUS
In 2010, Guglielmi and colleagues contacted 2,210 Italian women who had undergone QUS of the phalanges in 2006–2007. These women had an average age of 60.9 years, entered menopause at an average age of 49.3 years, and had a mean body mass index (BMI) of 26.5 kg/m2. By 2010, this group had experienced 108 new major osteoporotic fractures, including 23 hip fractures and 56 vertebral fractures. Investigators found a statistically significant correlation between QUS findings and fracture risk.
Chan and colleagues focused on 312 women 62 to 92 years of age who had femoral neck BMD, as measured by DXA, of –2.5 or better. QUS was measured as BUA at the calcaneus. The incidence of any fragility fracture was ascertained by radiographic reports during the follow-up period from 1994 to 2011. Eighty women (26%) experienced at least one fragility fracture during follow-up. After adjustment for covariates, women were significantly more likely to experience any fracture if BUA was decreased (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.13–1.99).