BACKGROUND: In post-menopausal women, the reduction of estrogen level is followed by gradual increase of bone absorption, accompanied by increased cytokine synthesis and bone metabolism disorder. Observation of serum interleukin-6(IL-6), osteocalcin(OC), estradiol(E2)and urinary pyridinoline (PYD) in women with osteoporosis may help understand role of these factors in the onset and development of osteoporosis.OBJECTIVE: To investigate the relationship of serum IL-6, OC, E2, and urinary PYD levels with bone metabolism in women with osteoporosis, so as to identify the factors responsible for the occurrence and development of osteoporosis.DESIGN: A case-controlled clinical observation.SETTING: Central Laboratory of Orthopedics, Nanshan People's Hospital of Shenzhen City.PARTICIPANTS: Between January 1999 and December 2001, 25 post-menopausal women with osteoporosis aged 42 -69 years were selected from the Department of Orthopedics, Nanshan People' s Hospital of Shenzhen to constitute the experimental group, with 10 healthy women from the same hospital serving as control group.METHODS: Two milliliters of fasting venous blood and 2 mL urine samples were collected from women in both groups in the morning to determine the contents of IL-6, OC, PYD and E2, respectively.MAIN OUTCOME MEASURES: Serum IL-6, OC, E2 and urinary PYD levels in the subjects.RESULTS: In the experimental group, the IL-6 level was(201.0±79. 9) ng/L, OC(25.5 ± 16.2) μg/L, and PYD(41.3 ±9.7) nmol/mmol (creatinine), all significantly higher than those in control group( t = 2. 159 -2. 953, P < 0.05-0.01) . Serum E2 level in the experimental group (79. 8 ± 73.2) ng/L, however, was significantly lower than that in control group ( t = 2.071, P < 0.05).CONCLUSION: IL-6, OC, PYD and E2 may play important roles in the occurrence and development of osteoporosis, and adjustment of the levels of these factors can be necessary in the treatment of women with osteoporosis.