Bone Density Score Calculator

Per WHO diagnostic criteria, a T-score of -1.0 or above is normal, a T-score between -1.0 and -2.5 is osteopenia (low bone mass), and a T-score of -2.5 or below is osteoporosis. If a T-score of -2.5 or below is also accompanied by a prior fragility fracture, this calculator classifies it as severe (established) osteoporosis rather than osteoporosis alone.

The T-score alone can't tell you whether low bone density is simply age-related or driven by something else. A Z-score at or below -2.0 -- meaning bone density well below what's expected for the patient's age and sex -- flags that possibility and typically prompts a workup for secondary causes such as hyperparathyroidism, vitamin D deficiency, or a malabsorption disorder, rather than attributing the low density to aging alone.

No. This calculator's fracture-risk estimate is a simplified, FRAX-inspired approximation built from age, T-score, sex, prior fracture, parental hip fracture, and BMI. The official FRAX tool is calibrated against country-specific fracture and mortality data and also considers factors like smoking, alcohol use, glucocorticoid use, and rheumatoid arthritis that this calculator does not collect, so treat this estimate as illustrative rather than a substitute for a validated FRAX calculation -- it is not used to drive the treatment recommendation for exactly this reason.

Only two things: a T-score of -2.5 or below (osteoporosis by WHO criteria), or a prior fragility fracture -- the same prior fracture that also upgrades an osteoporotic T-score to a severe (established) osteoporosis classification, and separately multiplies the estimated 10-year major fracture risk by roughly 1.85 in this calculator's risk model. Real NOF/NOGG guidance also recommends treatment for osteopenia (T-score between -1.0 and -2.5) when a validated FRAX calculation shows elevated risk -- this calculator deliberately does not implement that third trigger, because its own fracture-risk estimate above is illustrative, not a validated FRAX score, and using it to greenlight treatment could recommend pharmacologic therapy for bone density that WHO criteria alone would call normal or only mildly reduced.

Not reliably for the T-score-based classification and treatment threshold. Per ISCD guidance, WHO's T-score categories (normal/osteopenia/osteoporosis) are intended for postmenopausal women and men aged 50 and older; younger patients should be assessed by Z-score instead, since a low T-score in a younger person may simply reflect that comparison group's different reference range rather than clinically low bone density. This calculator's age input technically accepts ages down to 40, but its T-score-driven classification isn't validated for that population.