Association of adiposity with hemoglobin levels in patients with chronic kidney disease not on dialysis.

BACKGROUND: In the general population, adiposity influences erythropoiesis and iron metabolism. We aimed to assess the relationships between adiposity [estimated by body mass index (BMI) and abdominal circumference (AC)] and biomarkers of erythropoiesis in patients with chronic kidney disease (CKD) not on dialysis.

METHODS: A total of 2322 patients from the Chronic Kidney Disease Japan Cohort study were included. Patients were grouped according to BMI (low: < 18.5 kg/m2 , normal: 18.5-24.5 kg/m2 , and high: ≥ 25 kg/m2 ) and AC categories (large: ≥ 90 cm for men and ≥ 80 cm for women; small: < 90 cm and < 80 cm, respectively). Body composition and laboratory data were assessed at baseline, and at 1 and 2 years of follow-up.

RESULTS: Multivariate regression analysis of the 3 time-points showed that high BMI and large AC in male patients were significantly associated with higher hemoglobin levels. Hemoglobin levels were lower in female patients with low BMI and small AC than that in female patients with normal BMI and large AC, respectively; however, hemoglobin levels plateaued above a threshold of 25 kg/m2 for BMI and 80 cm for AC. While BMI and AC were positively associated with C-reactive protein levels, they were not associated with levels of transferrin saturation, ferritin, and erythropoietin in multivariate models.

CONCLUSIONS: Body composition appears to be associated with erythropoiesis; however, adiposity may be only associated with increased erythropoiesis in male patients. In addition, body composition does not appear to hamper iron metabolism in CKD patients not on dialysis.