Osteoporosis: Bone Loss, DEXA Scores & Prevention

DEXA Scan T-Score Interpretation

Risk Factors

• Female sex, post-menopause (oestrogen loss)
• Age over 65
• Corticosteroid use (prednisolone): most common drug cause
• Low BMI (<18.5)
• Family history of hip fracture
• Smoking and excessive alcohol
• Coeliac disease, inflammatory bowel disease, CKD (secondary causes)
• Previous fragility fracture: strongest predictor of next fracture

Why blood tests matter even though they cannot diagnose it

Osteoporosis is diagnosed by bone density scanning, not by blood tests, and in primary osteoporosis the standard blood panel is normal. The reason blood tests are still done is to find secondary causes, which account for a substantial minority of cases and change management entirely. A calcium, phosphate, alkaline phosphatase, vitamin D, parathyroid hormone, thyroid function, kidney and liver profile, full blood count and coeliac serology together identify most of them. In men and in younger people, secondary causes are proportionally more common and the search is correspondingly more thorough, including testosterone.

Secondary causes worth excluding

• Vitamin D deficiency and coeliac disease, both common and both correctable.
• Primary hyperparathyroidism and overactive thyroid, including over-replacement with levothyroxine.
• Long-term corticosteroids, the commonest drug cause, where bone loss is fastest in the first months.
• Myeloma, which can present as vertebral fractures and is why protein electrophoresis is often included.
• Early menopause, hypogonadism, chronic kidney or liver disease, and heavy alcohol use.

Fracture risk is not the same as bone density

Density is only one contributor to fracture. Age, previous fracture, parental hip fracture, smoking, alcohol, steroid use and rheumatoid arthritis all add risk independently, which is why calculators such as FRAX combine them with density to estimate ten-year probability. Someone with modestly reduced density and several clinical risk factors can carry a higher fracture risk than someone with a worse T-score and none. Falls risk matters just as much: most hip fractures involve a fall, so vision, balance, footwear and sedating medication deserve as much attention as the bone itself.

Treatment and its practical demands

Bisphosphonates remain first-line for most people. Oral preparations must be taken on an empty stomach with a full glass of plain water, sitting or standing upright for at least half an hour, because the drug is poorly absorbed and can irritate the oesophagus. Adequate calcium and vitamin D are assumed alongside, since treatment works poorly without them. Dental assessment before starting is advised where extensive work is anticipated. Treatment is normally reviewed after three to five years rather than continued indefinitely.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

1. Osteoporosis in Females. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK559156
2. Osteoporosis in Males. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK538531
3. Biochemical Markers of Osteoporosis. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK559306