Association between anemia and serum Klotho in middle-aged and older adults

The role of Klotho as a multifunctional protein in anemia is unclear. This study aimed to determine the association between anemia and serum Klotho concentrations in middle-aged and elderly populations.

In this cross-sectional study, we used data collected from the National Health and Nutrition Examination Survey (NHANES) 2007-2016. A total of 13,357 individuals who received serum Klotho measurements, biochemical tests, and demographic surveys were analyzed. Multivariate linear regression models adjusting for covariates were used to investigate the associations between anemia and serum Klotho.

Multivariable regression showed that serum Klotho correlates positively with hemoglobin and red blood cells and inversely with red cell distribution width. After adjusting for all covariates, compared with Q4, there was a significantly increased risk of anemia in serum Klotho quartiles 1 to 2 (OR=1.54, 95% CI:1.21-1.95, P=0.002; OR=1.30, 95% CI:1.02-1.64, P=0.042,respectively). Segmented regression showed that for every 100 pg/mL increase in serum Klotho <9.746 pg/mL, the risk of anemia was reduced by 10.9%, and this reduction was significant (P<0.001). Furthermore, stratified analyses yielded a stronger association between reduced anemia and high levels of Klotho in men and those with diabetes (P< 0.05 for interaction). However, this association was not found to be significantly altered by chronic kidney disease.

In summary, we indicated that low serum Klotho is associated with an increased likelihood of anemia using a nationally representative sample of middle-aged and older adults.