C4A and Hypertension: Moreover, levels of SBP, DBP, serum albumin, baseline 25(OH)D, TC, LDL-C, serum calcium, serum creatinine, eGFR, serum IgG, serum C4, the ratio of hypertension, and the number of VD receivers were significantly different between any two of the three groups (P < 0.05).