Blood sugar studies on premature babies

A survey of the management of neonatal hypoglycaemia within the Australian and New Zealand Neonatal Network

BACKGROUND

Neonatal hypoglycaemia is a common problem linked to both brain damage and death. There is controversy regarding both the definition of and best treatment for neonatal hypoglycaemia.

AIM

To determine current management of neonatal hypoglycaemia within the Australian and New Zealand Neonatal Network (ANZNN).

METHODS

Four questionnaires were sent to the Director of each of the 45 nurseries within the ANZNN. The Director was asked to complete one questionnaire and give the remaining three to other doctors involved with the management of babies with hypoglycaemia in the nursery.

RESULTS

One hundred and eighty surveys were sent and 127 were returned (71%), including at least one from each nursery. Almost all respondents (120, 94%) reported using a protocol to treat hypoglycaemia. Only 2 (2%) reported screening all babies for neonatal hypoglycaemia, with the remainder screening babies at risk. Only 67, (53%) reported that blood glucose levels were tested on an analyser generally considered to be reliable at low levels. Most respondents (99, 78%) reported the clinical threshold for treatment was <2.6 mmol/L. However, when provided with clinical scenarios, respondents reported a variety of interventions, including no treatment.

CONCLUSION

Doctors within the ANZNN are consistent about definition and screening for neonatal hypoglycaemia. However, frequently, the diagnosis is made using unreliable analysers. There is also wide variation in treatment, suggesting a lack of reliable evidence on which to base practice.

Glucose production in response to glucagon is comparable in preterm AGA and SGA infants

BACKGROUND AND AIMS

Low plasma glucose concentrations are more often detected in small-for-gestational-age (SGA) than in appropriate-for-gestational-age (AGA) infants. This is ascribed to impaired glucose production due to presumed lower liver glycogen stores in SGA infants. The change in glucose production induced by glucagon is considered to be an indicator of liver glycogen content. We compared the effect of glucagon on glucose kinetics in preterm AGA and SGA infants.

METHODS

In 5 AGA and 5 SGA preterm infants (postnatal age: 3-6 days) glucose production and gluconeogenesis were measured using stable isotopes immediately before and for 1 h after a bolus of glucagon.

RESULTS

After glucagon the plasma glucose concentration and glucose production increased significantly over time (P<0.05 and P<0.0001, respectively). The changes were comparable between AGA and SGA infants. Glycogenolysis contributed 75-80% to the increase in glucose production.

CONCLUSION

The increase in glucose production after glucagon was similar in preterm AGA and SGA infants, and mainly due to an increase in glycogenolysis. Based on the assumption that glycogenolysis is an indicator of liver glycogen content, our data do not support the hypothesis that liver glycogen content is lower in preterm SGA compared to AGA infants after the first postnatal day.

Neonatal hypoglycemia after beta-sympathomimetic tocolytic therapy

The effect of oral beta-sympathomimetic tocolytic therapy on neonatal serum glucose concentrations in the first several hours after delivery was examined in 12 babies. Hypoglycemia was noted in eight babies, and was sustained over at least a 30-minute period in five. The group with sustained hypoglycemia had a higher cord serum insulin concentration, a lower serum glucose nadir, and a more rapid initial rate of serum glucose disappearance than those babies with normoglycemia or transient hypoglycemia. Sustained hypoglycemia was observed in five of six babies delivered within two days of the termination of tocolytic therapy, but was not present in any of six babies delivered five or more days after the end of tocolytic therapy. Speculations as to the interaction between beta-sympathomimetic tocolytic drugs administered to the mother and fetal and neonatal glucose metabolism are made.