Phenotyping Kidney Function in Young Adults With High Blood Pressure: The African-PREDICT Study.

Biomarkers of kidney function, including glomerular, tubular, and fibrotic markers, have been associated with blood pressure in elderly populations and individuals with kidney and cardiovascular diseases. However, limited information is available in young adults. In this study, we compared levels of several kidney function biomarkers between normotensive and hypertensive young adults and explored the associations of these biomarkers with blood pressure within these groups. In this cross-sectional assessment, twenty-four-hour (24-h) blood pressure measurements of 1055 participants (mean age = 24.6 years) were used to classify hypertension as per the 2018 ESC/ESH guidelines. Biomarkers of kidney function included estimated glomerular filtration rate, urinary albumin, alpha-1 microglobulin (uA1M), neutrophil gelatinase-associated lipocalin (uNGAL), uromodulin (uUMOD), and the CKD273 classifier. All urinary biomarkers, except for the CKD273 classifier, were standardized for urinary creatinine (Cr). In the hypertensive group (61.0% White; 73.2% men), urinary albumin-to-creatinine ratio (uACR), uNGAL/Cr and uUMOD/Cr were lower than the normotensive group. In multiple regression analyses, 24-h systolic blood pressure (SBP) (β = 0.14; p = 0.042), 24-h diastolic blood pressure (DBP) (β = 0.14; p = 0.040), and 24-h mean arterial pressure (MAP) (β = 0.16; p = 0.020) associated positively with uA1M/Cr in the hypertensive group, while 24-h MAP positively associated with uACR (β = 0.17; p = 0.017). In exploratory factor analysis, positive associations of 24-h DBP and 24-h MAP with a factor pattern including tubular biomarkers were observed in the hypertensive group (24-h DBP: β = 0.18; p = 0.026, 24-h MAP: β = 0.17; p = 0.032). In the setting of hypertension, high perfusion pressure in the kidneys may play a role in the development of proximal tubule damage and promote early deterioration in kidney function in young adults. Trial Registration: ClinicalTrials.gov identifier: NCT03292094.