ALB and Hypertension: To estimate the threshold, we used GAM, and we made adjustments for relevant covariates, including age, sex, season, BMI, hemoglobin, eGFR, hypertension, diabetes, use of vitamin D supplements and RAS blockers, serum albumin, calcium, phosphorus, high-density lipoprotein (HDL) cholesterol, triglycerides, and high-sensitivity-C-reactive protein (hs-CRP), in a stepwise manner.