Serum leptin level in geriatric patients with hip fractures: Possible correlation to biochemical parameters of bone remodeling

Osteoporosis and hip fractures are a major public health problem. Since leptin was suggested to be involved in bone remodeling, its possible involvement in fracture formation/prevention was evaluated, by determination of serum leptin level in geriatric population with hip fracture, and evaluation the relationships with biochemical parameters of bone remodeling. We studied 250 geriatric patients with hip fracture admitted to Sapir Medical Center and underwent operative treatment. Among them 172 females and 78 males, with a mean age of 81 years. Serum leptin level of this total population distributed between 1 and 134 ng/ml. 40% of patients were in the normal range of our laboratory (10-40 ng/ml), 40% had decreased leptin level (<10 ng/ml) and 20% had higher leptin level (>40 ng/ml). No correlation was detected between serum leptin level and vitamin D-25(OH)D3, which was under normal range in 60% of the patients. Leptin also did not correlate to ICTP level, which was high in 80% of the patients, suggesting an extensive bone resorption in this population. Evaluation of leptin level in female versus male suggests that leptin level is higher in females than males also in this age (28.4 ng/ml vs. 14.4 ng/ml, p < 0.001). However, no difference were detected in either ICTP, or 25(OH)D3, which are involved in bone remodeling. The higher leptin levels in women was accompanied by higher serum levels of glucose, albumin, Ca, cholesterol, Na and FT4. Comparison of 50 patients with the lowest leptin levels (mean of 3.4 ng/ml) to 50 patients with highest leptin levels (mean of 34 ng/ml), did not indicate differences in both 25(OH)D3 and ICTP between these two populations in spite of the highly significant difference in leptin levels. The high range of serum leptin concentration in these geriatric patients with hip fracture of both sexes, and the absence of any correlation between leptin and the tested parameters of bone resorption and Ca metabolism, teleopeptide type I collagen (ICTP) and 25(OH)D3, does not support a direct massive involvement of serum leptin in hip fracture of the very old population.