OBJECTIVETo study the relationship between ultrasonic bone mineral density (BMD) of calcaneus and age, height, and body weight, and to establish the normal reference value for stiffness index (SI) of healthy subjects in Guangxi autonomous region and provide scientific foundation for the diagnosis and prevention of osteoporosis.

METHODSSI of calcaneus in 1 816 healthy adults aged 11-90 years (775 men, 1 041 women) were measured with quantitative ultrasound. According to their ages, all the men and women were divided into 13 groups by 5-year age group.

RESULTSSI reached peak values in 21-25 year group in men (range: 111.45 +/- 21.19) and in 16-20 year group in women (range: 101.26 +/- 17.51). Then the SI value began to decline with aging. The SI featured by a typical dual-peak curve in women and the decrease rate of SI was faster in women than in men over 61 years. Multivariate linear regression analysis showed significantly negative correlation between SI and age (P < 0.001), positive correlation between SI and body weight (P < 0.05 for men; P < 0.01 for women), and positive correlation between SI and height in women (P < 0.01).

CONCLUSIONSI correlates with age, height, and weight. The acquired SI value may provide a reference for the diagnosis of osteoporosis.