The Hidden Burden of Cyanotic Nephropathy: Prevalence and Correlates in Indian Children With Cyanotic Congenital Heart Disease at a Tertiary Center

Background: We observed a paucity of data on the prevalence of nephropathy in cyanotic heart diseases, with limited studies focusing on glomerular and tubular damage due to chronic hypoxia. Method: Over a period of 18 months, children with cyanotic congenital heart disease (CCHD) in the age range of 2-18 years attending the outpatient department or admitted to the wards were enrolled. Using basic laboratory parameters, including serum creatinine, urine albumin, urine protein, and urine creatinine, we calculated the albumin-to-creatinine ratio (ACR), protein-to-creatinine ratio (PCR), and estimated glomerular filtration rate (eGFR) to identify renal impairment. Result: Among the study population (n = 98), 80.61% had albuminuria (ACR > 30 mg/g of creatinine), and 54.08% had increased PCR (>0.2 mg/mg of creatinine). Based on eGFR, 39.79% had a GFR of less than 90 mL/minute (n = 39). Two (n = 2) had nephrotic range proteinuria, and none of the patients were in chronic kidney disease stage 4 or 5. Age-wise analysis revealed a higher prevalence of renal impairment in the 11-18-year age group compared to the two-to-five-year age group, indicating progressive renal dysfunction with uncorrected CCHD. Hematocrit (HCT) levels showed a significant association with renal impairment, with higher HCT levels (>65%) correlating with increased prevalence of renal impairment. Hypoxemia and lower oxygen saturation levels were also associated with increased albuminuria, suggesting their contribution to renal damage. Conclusion: The study highlights the prevalence of latent nephropathy (80.61%) in CCHD patients and its association with HCT levels, emphasizing the need for early recognition and monitoring of proteinuria and renal function.