What is the threshold for hypoglycemia in neonates?

• A. 40 mg/dL
• B. 60 mg/dL
• C. 50 mg/dL
• D. 30 mg/dL

Answer: (A)

Neonatal hypoglycemia is defined by a plasma glucose level roughly below 40 mg/dL, especially in the first 24 hours of life. This threshold is used because a newborn’s brain depends heavily on glucose for energy, yet newborns have limited glycogen stores and a high metabolic rate, so drops in glucose can rapidly affect brain function. If glucose falls under this level or if the infant shows symptoms (such as jitteriness, poor feeding, lethargy, apnea, or seizures), clinicians pursue prompt evaluation and treatment to prevent neurodevelopmental impact. Be aware that different measurement methods (capillary whole blood vs. plasma) can yield slightly different numbers, and some guidelines or at-risk populations may use modestly higher thresholds or require confirmation with plasma glucose. In contrast, much higher values (like 50–60 mg/dL) are not the standard cutoff for hypoglycemia in healthy term neonates, and very low values around 30 mg/dL indicate more severe hypoglycemia needing urgent management.