Verhoogde nachtelijke natriumexcretie correleert met nachtelijke hypertensie bij chronisch nierpatiënten

OBJECTIVE: Abnormal circadian blood pressure (BP) regulation is common in chronic kidney disease (CKD) and associated with adverse cardiovascular outcomes. In hypertensive individuals, higher nighttime natriuresis is linked to elevated nighttime BP, but evidence in CKD is limited. We hypothesized that impaired circadian renal sodium handling, characterized by increased nighttime natriuresis, would also be associated with higher nighttime BP and adverse nocturnal BP phenotypes. The primary aim was to examine differences in daytime and nighttime BP, dipping and nocturia frequency between CKD patients classified by nighttime-to-daytime urine sodium excretion ratio; secondary aim was to compare diurnal sodium excretion and nocturia between CKD patients with and without nocturnal hypertension. METHODS: One hundred and thirty patients with CKD stages 1-5 on stable antihypertensive treatment underwent 24-h ambulatory BP monitoring (ABPM) with the ABPMpro device and simultaneous split 24-h urine collection separated into daytime (7 : 00-23 : 00) and nighttime (23 : 00-7 : 00) periods. For analyses, patients were divided by tertiles of nighttime-to-daytime ratio of urine sodium excretion and by presence of nocturnal hypertension. RESULTS: No significant differences were detected in baseline characteristics across groups of nighttime-to-daytime sodium excretion ratio. In contrast to daytime SBP/DBP (T1: 124.8 ± 10.1/70.6 ± 7.9 vs. T2: 128.3 ± 12.2/74.6 ± 8.6 vs. T3: 128.6 ± 12.8/73.6 ± 8.2 mmHg, P = 0.254/P = 0.072 respectively), nighttime SBP and DBP (117.1 ± 12.0/64.8 ± 6.9 vs. 121.7 ± 13.1/68.7 ± 7.6 vs. 123.8 ± 13.1/69.3 ± 8.1 mmHg, P = 0.047/P = 0.014, respectively) showed significant increases across tertiles of nighttime-to-daytime sodium excretion. When patients with and without nocturnal hypertension were compared, those with nocturnal hypertension had similar daytime (83.8 ± 45.9 vs. 87.6 ± 50.6 mEq, P = 0.654), but higher nighttime urine sodium excretion (64.0 ± 34.5 vs. 49.7 ± 23.9 mEq, P = 0.012), higher nighttime-to-daytime sodium excretion ratio (0.73 [0.53] vs. 0.57 [0.63], P = 0.037) and more frequent nocturia (2 [2] vs. 1 [2.0], P = 0.006). Nighttime sodium excretion correlated with nighttime SBP (r = 0.212, P = 0.016) and DBP (r = 0.320, P < 0.001), while daytime sodium excretion did not. CONCLUSION: In CKD, impaired circadian renal sodium handling, characterized by increased nighttime natriuresis, is linked to higher nighttime BP and nocturnal hypertension. Assessment of nighttime urine sodium excretion may help identify sodium-related nocturnal hypertension and guide targeted therapeutic strategies.