Which manifestation might occur in a newborn with a blood glucose level of 30 mg/dl?

A blood glucose level of 30 mg/dl in a newborn indicates hypoglycemia, which can manifest in various ways. Jitteriness is a common and significant sign of low blood sugar in newborns. This jittery movement typically results from the body's response to low glucose levels, as the nervous system becomes more excitable when deprived of adequate glucose for energy.

In newborns, jitteriness can be mistaken for seizure activity, but in the context of hypoglycemia, it is a symptom that alerts healthcare providers to the need for immediate intervention to stabilize the infant's blood sugar levels. Other symptoms of hypoglycemia may include lethargy or weakness, but jitteriness is often more visibly noticeable and is a classic presentation that suggests the neonate requires further assessment and potential treatment.

The other manifestations listed may occur with different clinical conditions. For instance, hypotonia can indicate muscle weakness due to several factors but is not specifically linked to low glucose levels. Cyanosis relates to inadequate oxygenation and is a separate concern that does not primarily stem from hypoglycemia. Persistent crying can arise from numerous causes, including hunger or discomfort, but does not specifically indicate low blood sugar in the same direct manner that jitteriness does.