Relationship between leptin and bone mineral density in renal transplant recipients

Leptin plays an important role in regulating appetite and energy expenditure and also functions in the neuroendocrine, hematopoietic, and immune systems, among others. Leptin may be involved in modulating bone mineralization. The relationship between leptin and bone mineral density (BMD) is not clear. This study examined the relationship between BMD and serum leptin levels in renal transplant recipients.

Forty-one patients (28 men and 13 women; age 16 to 55 years) were grouped according to percentile of serum leptin level hypoleptinemic (<5th percentile, n = 14), normoleptinemic (between the 5th and 95th percentiles, n = 19), or hyperleptinemic (>95th percentile, n = 8). The patients also were grouped according to lumbar z score) and total femur z scores (>-2 vs <-2 for both).

The groups with different leptin statuses were compared with respect to age, sex distribution, and body mass index. Mean lumbar z score and mean lumbar BMD were higher in the hyperleptinemic group than in the normo- and hypoleptinemic groups (P < .05 for all). Considering the 42 patients overall, those with lumbar z scores >-2 had higher mean serum leptin/BMI than those with lumbar z scores <-2 (0.55 +/- 0.65 vs 0.18 +/- 0.23, respectively, P < .05). Serum leptin/BMI ratio was correlated with lumbar z score (r = .38, P < .05) and lumbar BMD (r = .32, P < .05).

In conclusion, the data indicate that elevated leptin level is associated with increased bone mass at lumbar sites in renal transplant recipients. This suggest that increased leptin has a bone-sparing effect, especially in the lumbar region, in this patient group.