Long-term follow-up of patients after acute kidney injury in the neonatal period: abnormal ambulatory blood pressure findings

Abstract

Background: Data on the long-term effects of neonatal acute kidney injury (AKI) are limited.

Methods: We invited 302 children who had neonatal AKI and survived to hospital discharge; out of 95 patients who agreed to participate in the study, 23 cases were excluded due to primary kidney, cardiac, or metabolic diseases. KDIGO definition was used to define AKI. When a newborn had no previous serum creatinine, AKI was defined as serum creatinine above the mean plus two standard deviations (SD) (or above 97.5^th percentile) according to gestational age, weight, and postnatal age. Clinical and laboratory features in the neonatal AKI period were recorded for 72 cases; at long-term evaluation (2-12 years), kidney function tests with glomerular filtration rate (eGFR) by the Schwartz formula, microalbuminuria, office and 24-h ambulatory blood pressure monitoring (ABPM), and kidney ultrasonography were performed.

Results: Forty-two patients (58%) had stage I AKI during the neonatal period. Mean age at long-term evaluation was 6.8 ± 2.9 years (range: 2.3-12.0); mean eGFR was 152.3 ± 26.5 ml/min/1.73 m². Office hypertension (systolic and/or diastolic BP ≥ 95^th percentile), microalbuminuria (> 30 mg/g creatinine), and hyperfiltration (> 187 ml/min/1.73 m²) were present in 13.0%, 12.7%, and 9.7% of patients, respectively. ABPM was performed on 27 patients, 18.5% had hypertension, and 40.7% were non-dippers; 48.1% had abnormal findings. Female sex was associated with microalbuminuria; low birth weight (< 1,500 g) and low gestational age (< 32 weeks) were associated with hypertension by ABPM. Twenty-three patients (33.8%) had at least one sign of microalbuminuria, office hypertension, or hyperfiltration. Among 27 patients who had ABPM, 16 (59.3%) had at least one sign of microalbuminuria, abnormal ABPM (hypertension and/or non-dipping), or hyperfiltration.

Conclusion: Even children who experienced stage 1 and 2 neonatal AKI are at risk for subclinical kidney dysfunction. Non-dipping is seen in four out of 10 children. Long-term follow-up of these patients is necessary.

Keywords: Acute kidney injury; Ambulatory blood pressure monitoring; Hyperfiltration; Long-term follow-up; Microalbuminuria; Neonate.

Fig. 1

Diagram showing the selection of patients in the study. In total, 72 subjects were analyzed for signs of long-term kidney dysfunction

Fig. 2

A Frequency of hypertension (by office blood pressure measurement), microalbuminuria and hyperfiltration among 68 patients: 23 patients (33.8%) had at least one abnormality (N = 68). B Frequency of hypertension (by ABPM), microalbuminuria and hyperfiltration among 27 patients: 11 patients (40.7%) had at least one abnormality (N = 27). C Frequency of abnormal ABPM (hypertension and/or non-dipping), microalbuminuria and hyperfiltration among 27 patients: 16 patients (59.3%) had at least one abnormality (N = 27). ABPM: ambulatory blood pressure monitoring, ACR: urinary albumin to creatinine ratio (mg/g), eGFR: estimated glomerular filtration rate, HT: hypertension

Fig. 3

The distribution of long-term kidney dysfunction parameters according to acute kidney injury stage. ABPM: ambulatory blood pressure monitoring, ACR: urinary albumin to creatinine ratio (mg/g), KDS: kidney dysfunction set, KDS-1: presence of microalbuminuria and/or hypertension by office blood pressure and/or hyperfiltration (eGFR > 187 ml/min/1.73m²), KDS-2: the presence of microalbuminuria and/or hypertension with ABPM or hyperfiltration, KDS-3: the presence of microalbuminuria and/or abnormal ABPM (hypertension and/or non-dipping) or hyperfiltration