Background: Congenital heart disease (CHD) is a prevalent congenital disability, affecting approximately 1% of live births. Survival rates have increased due to improvements in medical and surgical care, yet patients with CHD remain at risk for multi-organ complications, including renal dysfunction. This study aimed to investigate microalbuminuria as an early sign of renal impairment in children with congenital heart disease by assessing both urinary microalbumin levels albumin-to-creatinine ratios (ACR), comparing these parameters among cyanotic CHD patients, acyanotic CHD patients, healthy controls.

Methods: This study was conducted as a case-control study to evaluate microalbuminuria as an indicator of renal impairment among children diagnosed with CHDs. Fifty-one participants were allocated equally into Group 1: Children with acyanotic CHD, Group 2: Children with cyanotic CHD, and Group 3: Healthy controls. All participants underwent detailed clinical evaluation and laboratory investigations, including complete urine analysis, urinary microalbumin, urinary creatinine, and the calculation of the urinary albumin-to-creatinine ratio (ACR).

Results: A significant increase in urinary microalbumin (2.54 ± 2.04 mg/dL) ACR (42.11 ± 27.86 mg/g) was found in the cyanotic CHD group compared to acyanotic CHD (0.62 ± 0.51 mg/dL 11.24 ± 7.64 mg/g, respectively) and controls (0.61 ± 0.24 mg/dL 8.25 ± 2.61 mg/g, respectively), with P < 0.0001.

Conclusion: This study's findings highlight microalbuminuria elevated ACR as valuable early indicators of renal impairment in children with CHD, particularly among cyanotic cases. The markedly higher levels observed in the cyanotic group may reflect the effects of chronic hypoxia altered hemodynamics commonly associated with these conditions.