Measures of adiposity correlate with renal filtration in young nulliparous women: An observational cohort study

OBJECTIVE: Renal hyperfiltration, which has been documented in severe obesity and obesity‐associated hypertension, can occur with hypertensive disorders of pregnancy. Identification of prepregnancy risk factors for unrecognized renal hyperfiltration could inform screening and intervention strategies to protect against pregnancy complications. In young, healthy, nulliparous women, associations between associations between measures of adiposity, insulin resistance, and renal vascular resistance were thus evaluated. METHODS: This is a secondary analysis of a prospective observational trial characterizing associations of prepregnancy and late‐pregnancy maternal physiology. Seventy‐nine nulligravid women aged 18‐42 years without major medical conditions were assessed for percent android body fat using dual‐energy X‐ray absorption. Renal cortical vessel blood flow resistance index (CVRI) was determined using Doppler ultrasonography. Creatinine clearance was calculated from 24‐hour urine collection. RESULTS: Renal CVRI inversely correlates with body mass index (r = ‐0.23, p = 0.047), percent android fat (r = ‐0.30, p = 0.008), and supine pulse (r = ‐0.44, p < 0.001). Creatinine clearance is positively associated with BMI and HOMA‐IR. In regression modeling, supine pulse (r(2) = 0.22, p < 0.001) and cardiac index (r(2) = 0.05, p = 0.045) predict renal CVRI, whereas HOMA‐IR (r(2) = 0.11, p = 0.008) and cardiac output (r(2) = 0.06, p = 0.039) predict creatinine clearance. Measures of adiposity are not independently predictive of either measure. CONCLUSIONS: In healthy young women, measures of adiposity and insulin resistance correlate positively with renal filtration. Preclinical manifestations of renal hyperfiltration may have implications for pregnancy outcomes.