Role of adiponectin in the relationship between visceral adiposity and fibroblast growth factor 23 in non-diabetic...

Fibroblast growth factor 23 (FGF23) is a key regulator of phosphate metabolism. Circulating FGF23 levels are associated with obesity, metabolic syndrome, and cardiovascular disease in the general population, but the underlying mechanism remains unclear. Therefore, we aimed to determine the associations between serum FGF23 levels and visceral adiposity as well as serum adiponectin levels in 189 adults without diabetes and with normal kidney function who were selected from the MedCity21 health examination registry. The exclusion criteria included diabetes mellitus or impaired kidney function (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²). Levels of serum FGF23 and total adiponectin, and visceral fat area (VFA) on computed tomography images were measured. Serum FGF23 levels were higher and VFA was greater, whereas serum adiponectin levels were lower in men than in women. Serum FGF23 levels positively correlated with VFA in men; they remained marginally significant after adjusting for age, eGFR, and serum levels of calcium, phosphate, intact parathyroid hormone, and 1,25-dihydroxyvitamin D. Importantly, when serum adiponectin levels were included as a covariate, serum adiponectin levels comprised an independent determinant of serum FGF23 levels in men, whereas VFA did not. In conclusion, lower serum adiponectin, rather than a greater VFA, was associated with higher serum FGF23 levels in non-diabetic men with normal kidney function. These findings suggest that adiponectin plays a role in the relationship between visceral adiposity and FGF23 in men.