Platelet and white blood cell counts correlate with leptin and body mass index in Japanese adolescents

Obesity is associated with mild chronic inflammation, frequently observed along with increased platelet and white blood cell (WBC) levels in adults. We aimed to clarify the relationship between peripheral blood cell count, body mass index standard deviation score (BMI-SDS), and adipocytokine levels in obese adolescents. Participants included 31 patients with obesity (age: 13.1 ± 3.1 yr) and 28 normal-weight controls (age: 13.3 ± 1.9 yr). Obesity was defined as a percentage of overweight ≥ 20%; patients with type 2 diabetes were excluded. As sex differences were observed in blood cell counts, the analysis was performed after adjusting for sex differences. The obese group has significantly higher WBC, red blood cell, and platelet counts, as well as high serum leptin levels and Homeostasis Model Assessment of insulin resistance (HOMA-IR) scores compared with those of the control group. In all participants, BMI-SDS significantly correlated with WBC and platelet counts. Platelet count correlated with serum leptin and glucose levels, whereas WBC count correlated with serum leptin, insulin, HOMA-IR, and glucose levels. Statistical analysis showed that serum leptin level significantly influenced the platelet count and HOMA-IR score affected WBC count. Increased platelet and WBC counts in adolescents with obesity may increase the risk of thrombosis.