Correlation between neonatal hyperbilirubinemia and vitamin D levels: A meta-analysis

Hyperbilirubinemia is a common disease in the neonatal period, and hyperbilirubinemia may cause brain damage. Therefore, prevention and diagnosis and management of hyperbilirubinemia is very important, and vitamin D may affect bilirubin levels. To evaluate the relationship between neonatal hyperbilirubinemia and vitamin D levels.

The China National Knowledge Infrastructure, VIP, Wanfang, Chinese Biology Medicine Disc, PubMed, Web of Science, Cochrane Library, and Embase databases as well as clinical trial registries in China and the United States were searched for relevant studies from inception to September 2020 without restrictions on language, population, or year. The studies was screened by two reviewers independently, the data were extracted, and the risk of bias of the included studies was evaluated using the NOS. A meta-analysis was conducted on the included studies using Stata11 software.

Six case-control studies were included, and the methodological quality of the studies was high (grade A). The studies included 690 newborns; more than 409 were diagnosed with hyperbilirubinemia. The means and standard deviations were calculated. Meta-analysis results showed that neonatal vitamin D levels were 7.1 ng/ml lower among infants with hyperbilirubinemia than among healthy newborn levels (z = 6.95, 95% CI 9.10 ~ 5.09, P < 0.05). Subgroup analysis was conducted based on whether the bilirubin levels were concentrated in the 15 to 20 mg/dl range. Vitamin D level of infants with hyperbilirubinemia (the bilirubin levels were concentrated in the 15 to 20 mg/dl range) was 9.52 ng/ml (Z = 15.55, 95% CI-10.72~-8.32, P<0.05) lower than that of healthy infants. The bilirubin levels in four cases were not concentrated in the 15-20 mg/dl range. The results showed that the vitamin D level of hyperbilirubinemia (The bilirubin levels were not concentrated in the 15-20 mg/dl range) neonates were 5.35 ng/ml lower than that of healthy neonates (Z = 6.43, 95% CI-6.98~-3.72, P<0.05).

Vitamin D levels were observed to be lower in neonates with hyperbilirubinemia as compared to term neonates without hyperbilirubinemia in this study. This can possibly suggest that neonates with lower vitamin D levels are at higher risk for developing hyperbilirubinemia.