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High FGF23 levels tied to adiposity, BMI
Greater adiposity and increased BMI category are significantly associated with higher fibroblast growth factor 23, or FGF23, levels in people with normal kidney function, study data show.
Sarah Zaheer, MD, of the division of endocrinology, diabetes and hypertension at Brigham and Women’s Hospital, Harvard Medical School, and colleagues evaluated data from the Multi-Ethnic Study of Atherosclerosis (MESA) on participants with an estimated glomerular filtration rate of at least 60 mL/min/1.73 m2 to determine whether greater adiposity results in higher FGF23 levels. The association between crude (BMI, waist circumference and waist-to-hip ratio; n = 5,610) and more refined (abdominal adipose tissue area by CT; n = 1,313) measures of adiposity and FGF23 were evaluated using multivariable linear regression.
Overall, the mean age of participants was 60.8 years, 52.8% were women, mean BMI was 28.2 kg/m2 and mean concentrations were as follows: FGF23, 38.8 pg/mL; 25-hydroxyvitamin D levels, 25.3 ng/mL; parathyroid hormone, 43.2 pg/mL; calcium, 9.6 mg/dL; phosphate, 3.7 mg/dL; and eGFR, 82 mL/min/1.73 m2. Participants in the CT subgroup had similar baseline characteristics.
Among participants who did not undergo CT, higher BMI was related to lower 25-(OH)D, serum calcium and urinary calcium excretion levels and higher parathyroid hormone levels. Higher FGF23 levels were associated with increasing BMI categories, larger waist circumference and greater waist-to-hip ratio.
Among the subset of participants who underwent CT, higher BMI was associated with larger area of total abdominal adipose tissue, and more abdominal adipose tissue was associated with lower 25-(OH)D level and urinary calcium excretion and higher parathyroid level. Greater adiposity was tied to higher FGF23 level.
“We observed that higher adiposity, as measured by BMI and abdominal adipose area by CT, was independently associated with higher FGF23 levels in a large cohort of participants with normal eGFR,” the researchers wrote. “Higher FGF23 activity with greater adipose tissue burden may provide an additional explanation for the increased adverse skeletal outcomes seen in obesity. Further studies are needed to better understand the causes and consequences of high FGF23 in states of greater adiposity.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.