![]() ![]() 7,8 What Are the Causes of Premenopausal Osteoporosis? It is estimated that the “peak” bone mass has a relatively greater influence on the development of osteoporosis in adulthood than the bone loss that occurs with age. Several factors were independently associated with increased bone mass, such as maintaining a BMI within the normal range at menarche, physical exercise involving mechanical loading during adolescence and normal pubertal development. At the end of the second decade of life, it is very similar in both sexes and lasts until age 40. Peak bone mass is genetically determined, but life habits, exercise and diet, and hormonal factors may contribute to this acquisition. Low BMD in premenopausal women is the result of the acquisition of a low peak bone mass, its subsequent loss, or both. However, there are no studies on this in our environment. Moreover, as in any silent disease that causes symptoms in its early stages, it is probably an underdiagnosed disease. 5 Note that the presence of fractures in this group, with particular emphasis on those affecting the distal radius, is associated with decreased bone mass and also constitutes a risk factor for fractures in older adults. 4 Studies examining the incidence of fractures in this group are limited it is estimated that the incidence of vertebral fractures in younger patients (<35 years) is 3 per 100 000/year and rises to 21 in the population aged 35–44 years but often are due to trauma. The prevalence of osteoporosis by densitometry in younger women (20–44 years) of our population is 0.34%–0.17% in the lumbar spine and femoral neck, respectively. In fact, there are few studies on its actual incidence. Postmenopausal osteoporosis is well documented and studied, but the pre-menopausal osteoporosis has been given less attention probably because of its low incidence. On the other hand, the risk of fractures in postmenopausal women is higher than that of premenopausal women with the same BMD as premenopausal women have better estrogen stimulation, increased muscle mass, thicker bone cortex, less bone turnover and fewer falls. This consideration is due to the fact that low BMD in a young individual can translate only a poor acquisition of peak bone mass and not related to an increased risk of fracture. However, for a premenopausal osteoporosis diagnosis, it is recommended not relying solely on densitometric parameters and taking into account the presence of other risk factors and a history of fragility fractures and diseases or bone loss inducing drugs. The International Society for Clinical Densitometry has suggested that these criteria should not apply to young women and has argued for the use of the Z value in this population group: a value of Z less than −2 at the lumbar spine or femur indicate a BMD value below normal for the age and sex of the individual. However, there is no agreement in defining osteoporosis in premenopausal women and the diagnosis must be done carefully so as to not rely solely on densitometry 3 parameters. ![]() 1 In 1994 a committee of experts from the World Health Organization proposed the term densitometric osteoporosis, defining a category applicable to postmenopausal white women who had a bone mineral density (BMD) less than or equal to −2.5 standard deviations from a young population of same sex, that is, a T value less than −2.5. Osteoporosis is defined as a bone disease characterized by decreased bone strength that predisposes fractures. I abided by the instruction not to take any medications that could contain calcium 24 hours before the exam as it could skew the results.What Is Premenopausal Osteoporosis and How Is It Diagnosed? The imaging center that performed my QCT could not give me an appointment for several months, so the DXA was scheduled in a Scripps outpatient department in La Jolla, California, on March 26. I told my doctor, also an endocrinologist, about Clarke's comment about QCT's inaccuracy of the spine T-score, and asked him to refer me for a DXA. "So in your case, maybe you've got normal bone density if you did it by a DXA." Almost every time, they don't have osteoporosis, he said. So they come to the Mayo for a second opinion, get a DXA. Patients from Iowa just to the south, who for some reason get a lot of QCT studies for their BMD evaluations instead of DXA scans, are told they have osteoporosis of the lumbar spine and must go on medication. He said something astonishing: "The QCT over-reads the severity of the bone loss in the spine." He sees it all the time. That theme led me to Bart Clarke, MD, an endocrinologist and bone metabolism expert at the Mayo Clinic in Rochester, Minnesota, who set my story on a different trajectory. ![]()
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