Interdialytic blood pressure is independent of weight gain and correlated with serum angiotensin II levels in adults.

Chronic volume overload is a major risk factor of hypertension and mortality in chronic dialysis patients. However, the mechanisms responsible for hypertension are unclear. We studied 32 patients (age 23-68 years, 19 females) in chronic hemodiafiltration classified by their interdialytic ambulatory blood pressure (idABP, mmHg) in three groups: Group A: <130/80 (7 normotensives and 8 patients with controlled hypertension), Group B: 130-139/80-89 (insufficiently controlled hypertension, n = 7), and Group C: ≥140/90 (uncontrolled hypertension, n = 10). Studies included interdialytic weight gain (IDWG), idABP, predialysis blood pressure changes (Δ BP), cardiac output (CO), systemic vascular resistance (SVR), and serum concentrations of angiotensin II, norepinephrine, and copeptin. SVR and CO relationship and range were similar in all patient groups, but SVR was >1500 dynes/s/cm-5 in two-thirds of the patients. Angiotensin II (pg/mL) was higher (p = 0.016) in group C (231.5 ± SD 127.8) than in group A patients (105.3 ± 46.5) and was positively correlated with CO (p = 0.002) and with idABP (p = 0.027). There were no significant differences in IDWG among the patient groups. idABP, Δ BP, CO, and SVR were unrelated to IDWG. Males had a higher (p = 0.045) systolic idABP than females. Results suggest that angiotensin II drives idABP independently of IDWG.