Table 1.

Bone mineral density (BMD) definitions by various organizations.^59,62,93

	World Health Organization		International Society for Clinical Densitometry		American College of Sports Medicine
Population	Postmenopausal women		Premenopausal women		Premenopausal female athletes
Terminology	Osteopenia	Osteoporosis	BMD within expected range for age	BMD below expected range for age	Low BMD	Osteoporosis
Criteria	T-Score: −1 to −2.5 (1 to 2.5 SD below the average value for young healthy women)	T-Score: ≤ −2.5 (2.5 SD or more below the average value for young healthy women)	Z-Score: > −2 (< 2 SD below the average value for age-, sex-, and race- matched controls)	Z-Score: ≤ −2 (2 SD or more below the average value for age-, sex-, and race- matched controls)	Z-Score: −1 to −2 with secondary clinical risk factors for fracture (eg, chronic malnutrition, eating disorders, hypogonadism, glucocorticoid exposure, previous fractures)	Z-Score: ≤ −2 with secondary clinical risk factors for fracture