Ambulatory Blood Pressure Monitoring in Frequently Relapsing Nephrotic Syndrome.

OBJECTIVES

To screen patients with frequently relapsing nephrotic syndrome (FRNS) for the presence of ambulatory hypertension and left ventricular hypertrophy.

METHODS

Following ethical and parental approvals, consecutive patients with FRNS of ≥2 y duration were enrolled. Those with estimated glomerular filtration rate <60 ml/min/1.73 m2 and known familial hypercholesterolemia or diabetes mellitus were excluded. Clinic blood pressure was measured by oscillometry and 24-h ambulatory blood pressure was recorded by Spacelab 90207; echocardiography was done for left ventricular mass. Ambulatory hypertension was defined as the presence of clinic blood pressure >95th centile for age, sex and height, and systolic blood pressure load exceeding 25 %.

RESULTS

Of 99 patients, 73 were boys; their median (IQR) age was 120 (84-156) mo. Clinic blood pressure was >95th percentile in 63 (63.6 %) patients. Ambulatory hypertension was present in 33 (33.3 %), including 14 patients with severe hypertension; 16 (16.1 %) had masked hypertension and 30 (30.3 %) had white coat hypertension. Non-dipping was seen in 72 and 55 patients had high nocturnal systolic blood pressure load. Of 21 patients with increased left ventricular mass index, 9 (42.9 %) had ambulatory hypertension, 3 (14.3 %) had masked hypertension and 6 (28.6 %) patients had white coat hypertension. Compared to those with normal blood pressure, patients with ambulatory hypertension were younger at onset of nephrotic syndrome (odds ratio, OR 0.94; 95 % CI 0.91-0.98; P = 0.002), longer duration of frequently relapsing disease (OR 1.05; 95 % CI 1.00-1.10; P = 0.034) and higher body mass index (BMI) (OR 1.61; 95 % CI 1.07-4.40; P = 0.020). BMI was positively correlated with 24-h systolic blood pressure load (r = 0.23; P = 0.002) and with the left ventricular mass index (r = 0. 57; P = 0.001).

CONCLUSIONS

Many patients with FRNS showed high prevalence of clinic, ambulatory and white coat hypertension, emphasizing the need to carefully screen these patients in order to ensure their appropriate management. While clinic blood pressure monitoring detects most patients with hypertension, it misses a significant proportion with masked hypertension, underscoring the need for ambulatory blood pressure monitoring and screening for end organ damage. High BMI was the chief risk factor for hypertension, suggesting that control of overweight and hypertension might improve cardiovascular outcomes.