What blood glucose reading indicates hypoglycemia in a newborn?

In newborns, hypoglycemia is typically defined as a blood glucose concentration that falls below a specific threshold. A blood glucose reading of less than 30 mg/dL is widely recognized as the indicator for hypoglycemia in this population. Newborns are particularly vulnerable to low blood glucose levels due to their limited glycogen stores and the transitional changes their bodies undergo after birth. As such, maintaining an adequate blood glucose level is crucial for their overall metabolic function and neurological health.

Readings of 30-45 mg/dL can indicate a mild to moderate level of hypoglycemia, depending on the clinical context, but are not universally accepted as the definitive cut-off for diagnosing hypoglycemia in newborns. Values higher than 45 mg/dL are generally considered adequate for newborns, reflecting a stable metabolic state. Thus, the critical threshold that indicates hypoglycemia is indeed a value less than 30 mg/dL, making this the correct answer.