Serum leptin and osteoporosis in postmenopausal women with primary knee osteoarthritis

Aim of the workThe purpose of this study was to evaluate the relationship of serum leptin level and osteoporosis in postmenopausal women with knee osteoarthritis (KOA).Patients and methodsThe study included 40 postmenopausal women with primary KOA and 37 age-matched postmenopausal healthy controls. Plain X-ray knees were performed and assessed using the Kellgren–Lawrence (KL) grading scale. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry (DXA) in lumbar spine, hip and forearm regions. As a bone turn-over marker serum osteocalcin was measured. Serum leptin level was assessed in patients and control.ResultsThe mean age of the KOA patients was 58.05 ± 5.7 years. Osteoporosis was detected among 15% of the KOA patients and 35.1% of the control. The BMD was significantly increased at the spine and wrist in the patients than in the control (p = 0.011 and p = 0.015 respectively). The serum osteocalcin was comparable between patients (19.74 ± 8.05 ng/ml) and control (21.2 ± 8.36 ng/ml) (p = 0.5). Serum leptin was significantly higher in the patient (58.7 ± 27.17 ng/ml) compared to the control (48.75 ± 13.19 ng/ml) (p = 0.048), and significantly correlated with the degree of KOA (p = 0.017). No significant correlation was found between serum osteocalcin level or the BMD and the degree of KOA. There was a significant negative correlation between serum osteocalcin level and forearm BMD in KOA patients (r = −0.33, p = 0.038).ConclusionsAlthough postmenopausal women with KOA had significantly higher BMD, both diseases can coexist. It seemed that osteoarthritis does not prevent the occurrence of osteoporosis. Our study suggested a promising role of leptin as a biomarker of KOA.