Serum lactate dehydrogenase as an early diagnostic biomarker to differentiate respiratory distress syndrome from transient tachypnea of the newborn

Background: Early differentiation between respiratory distress syndrome (RDS) and transient tachypnea of the newborn (TTN) remains clinically challenging, particularly in settings where imaging and advanced diagnostics may be delayed. Lactate dehydrogenase (LDH) is a marker of cellular injury and hypoxic stress and may assist in early etiologic discrimination. Objectives of the study were to evaluate the diagnostic performance of serum LDH measured within the first 12 hours of life in differentiating RDS from TTN, and to examine whether LDH provides independent diagnostic value beyond gestational age and birthweight. Methods: In this prospective diagnostic study, 151 neonates were enrolled: 50 normal controls, 63 with TTN, and 38 with RDS. Serum LDH levels were measured within 12 hours of birth. Group comparisons were performed using appropriate parametric or non-parametric tests. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis. Univariable and multivariable logistic regression models were constructed to evaluate the independent association of LDH with RDS. Results: LDH levels differed significantly across groups, demonstrating a stepwise increase from normal neonates to TTN and RDS (p