658 Obstetrics and Gynecology Board Review •••
❍ What are the WHO criteria for diagnosing osteoporosis using dual-energy X-ray absorptiometry (DXA)
bone mineral density (BMD) measurement?
Category T-Score
Normal ≥ –1.0
Low bone bass (osteopenia) <–1 or > –2.5
Osteoporosis ≤2.5- T-Score is the BMD measurement (preferably the femoral neck, total hip, and lumbar spine) of the patient
compared with the mean BMD of a young, healthy cohort of females. - A Z-score is also reported; it compares the patient’s BMD with the mean BMD of women her age. This score
can be of value when it demonstrates that a woman’s BMD is significantly below than that of her peer group. It
is NOT used to diagnose osteoporosis.
❍ How do you make a clinical diagnosis of osteoporosis in the absence of DXA imaging?
- Medical history of low-trauma fracture (especially vertebral or hip) in an at-risk woman.
- History of low-trauma fractures that occur in a situation that would not be expected to cause fractures in most
individuals (eg, a vertebral fracture from opening a window).
❍ What is the fracture risk assessment tool (FRAX)?
- A tool that predicts the risk of osteoporotic fracture for a person in the next 10 years.
- Used as an aid in decision making regarding treatment initiation when a patient’s BMD score is in the low bone
mass range. - Clinical risk factors used in the tool include, age, sex, BMI, previous fragility fracture, parental hip fracture,
current smoking status, corticosteroid use (≥5 mg prednisolone per day for 3 months), alcohol intake ≥3 units
per day, rheumatoid arthritis, and other secondary causes of osteoporosis. - Results are specific for gender and race for various countries where fracture data were available to incorporate
into the tool. - Limitations: can only be used in postmenopausal, who are not receiving osteoporosis treatment, and have no
prior hip or vertebral fracture.
❍ How does FRAX help in clinical decision making?
- Treatment for osteoporosis should be initiated in women who have a T-score from –1 to –2.5 and a FRAX
score ≥3% for risk of hip fracture or a FRAX score ≥20% for risk of a major osteoporotic fracture (defined as
forearm, hip, shoulder, or clinical spine fracture) or both in the next 10 years. - The tool can be used to determine if screening is necessary prior to age 65.
- It can be a useful tool for a concerned patient who does not meet criteria for a DXA scan.
- FRAX should be used on an annual basis to monitor the important effect of age on fracture risk.