Serum concentrations of perfluoro-1-heptane sulfonate (PFHpS) among US adults: variabilities across different stages of kidney function.

For the first time, data (N = 1311) from US National Health and Nutrition Examination Survey for 2017-2018 were analyzed for gender and racial/ethnic differences for perfluoro-1-heptane sulfonate (PFHpS) for US adults aged ≥ 20 years. In addition, variability in adjusted concentrations across various stages of glomerular filtration (GF) was also studied. While no racial/ethnic differences were observed, males had statistically significantly higher concentrations of PFHpS than females (0.30 vs. 0.19 ng/mL, p < 0.01). Concentrations of PFHpS across various stages of kidney function were located on inverted U-shaped curves with point of inflection located at GF-3A (45 ≤ eGFR < 60 mL/min/1.73 m 2 ) for all participants, males, as well as females. After moderate increase from GF-1 (eGFR ≥ 60 mL/min/1.73 m 2 ) to GF-2 (60 ≤ eGFR < 90 mL/min/1.73 m 2 ), the increase in PFHpS concentration from GF-2 to GF-3A was quite steep. For example, for females, concentration from GF-1 to GF-2 increased from 0.17 ng/mL to 0.23 ng/mL for an increase of 35% but from GF-2 to GF-3A, concentrations of PFHpS increased from 0.23 ng/mL to 0.43 ng/mL for an increase of about 87%. Following this, at GF-3B/4 (15 ≤ eGFR < 45 mL/min/1.73 m 2 ), concentrations decreased sharply to the almost the same levels as for GF-1. For example, for males, the decrease from GF-3A (0.67 ng/mL) to GF-3B/4 (0.21 ng/mL) was about 69%. Concentration curves for each race/ethnicity were also located on inverted U-shaped curves but relatively very small sample sizes for Hispanics and non-Hispanic Asians, and others at GF-3A and GF-3B/4 lead to substantial variability. The balance between reabsorption-excretion in favor of reabsorption at GF-1 and GF-2 switched to in favor of excretion starting at the end of GF-3A.