Clinical presentation

Hypoglycaemia may be picked up incidentally in an asymptomatic baby.

Blood glucose should be measured regularly in vulnerable babies (see below).

Symptoms are non-specific:

• Neuroglycopaenic symptoms of hypoglycaemia include apnoea, hypotonia, jittering, irritability, lethargy, abnormal cry, feeding problems, convulsions, and coma.

• Autonomic symptoms (pallor, sweating, tachypnoea) are generally not prominent in the newborn.

• Macrosomia may be present in infants of diabetic mothers.

• Macrosomia in the absence of a history of maternal diabetes suggests hyperinsulinism.

• Macrosomia with magroglossia, organomegaly, exomphalos, or ear lobe creases suggests Beckwith–Wiedemann syndrome (approximately 80% demonstrate genotypic abnormalities of the distal region of chromosome 11p).

• Midline defects, micropenis, and jaundice suggest hypopituitarism (see Chapter 7).

• Babies can have low blood glucose levels and be completely asymptomatic.

Approach to the problem

• Asymptomatic healthy term babies of normal birth weight (9th to 91st centiles) do not require blood sugar measurements.

• Symptomatic hypoglycaemia in a term baby is always pathological until proved otherwise.

Babies at risk of hypoglycaemia

• Preterm or intrauterine growth retardation: lack of glycogen stores, immature enzymes involved in glucose homoeostasis, inappropriately high insulin levels.

• History of birth depression: lack of glycogen stores due to utilization.

• Infants of diabetic mothers, large-for-dates babies, babies with Beckwith–Wiedemann syndrome, babies with rhesus disease: excessive insulin secretion.

• Polycythaemia: excessive metabolism of glucose by erythrocytes.

• Congenital heart disease, sepsis, hypothermia: excessive glucose demands.

• […]