Hypoglycaemia

Published on 03/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 22/04/2025

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CHAPTER 11 Hypoglycaemia

Mark Davies, David Cartwright

Background

Hypoglycaemia is defined as a blood sugar level (BSL) of <2.6 mmol/L as measured by a bedside glucometer or a blood gas machine. 1 mmol/L = 18 mg/dL.

Blood glucose assessments should be routinely undertaken on premature infants, infants whose birth weight is <10th percentile for their gestational age, infants of diabetic mothers, and other macrosomic babies — at 1 hour, 2 hours and 4 hours of age, then every 4 hours for 24 hours until stable.

• The laboratory blood glucose is often higher than the bedside measurement.
• Any low or borderline BSL should be confirmed with a laboratory or a blood gas machine measurement.

Management

The basic principle of managing hypoglycaemia is to give the baby more sugar than it is currently getting.

Options for treatment are:

If BSL is 2.0–2.5 mmol/L:

1. Feed with milk (not glucose water).
2. Feed more frequently, e.g. every 1–2 hours if necessary.

If BSL is <2.0 mmol/L:

3. Start 10% glucose IV at 60 to 75 mL/kg/day.
4. Increase the dextrose infusion rate or concentration.
• Usually just increasing the amount of dextrose infused is enough — i.e either:

— increase the rate of infusion (e.g. from 0 to 60 mL/kg/day, or from 60 to 80); or
— increase the strength of the infusion (e.g. from 10% to 12% dextrose, then 14%, 18%). If you need to give more than 12% dextrose, use a central line or umbilical venous line.

To make a solution of dextrose stronger than 10%: image of the volume of 10% dextrose + ½ of the volume of 50% dextrose

= the % dextrose per 100 mL of solution.

e.g. 95 mL of 10% dextrose + 5 mL of 50% dextrose

= 9.5 + 2.5 = 12
i.e. 100 mL of 12% dextrose.

Notes on dextrose

• Bolus doses of dextrose are almost never required and run the risk of rebound hypoglycaemia. Rarely a bolus may be needed: 2–3 mL/kg of 10% dextrose (200–300 mg/kg) initially.
• Never give a bolus of dextrose without increasing the amount infused as well.
• Check the BSL again 1 hour after any increase or bolus.

Additional drug treatment

Drug treatment may sometimes be necessary for hypoglycaemia that is not responding to simple measures as above. Next options for recalcitrant hypoglycaemia are to add hydrocortisone, glucagon, diazoxide or octreotide.

• Glucagon mobilises glycogen stores, so is not particularly useful for growth-restricted babies; it is good for infants of diabetic mothers and for other hyperinsulinaemic states.

— The dose is 0.04 mg/kg IV or IM, then 10–50 μg/kg/hr. (1 mg/kg of glucagon made up to 50 mL in Nsaline gives a solution which when run at 0.5 mL/hr delivers 10 μg/kg/hr of glucagon. Nsaline is Normal saline, 0.9%)

• Hydrocortisone primarily increases gluconeogenesis and has a slow response.

— The dose is 1 mg/kg/dose every 6 hours IV.

• Diazoxide and octreotide should be reserved for established diagnosis of hyperinsulinaemia, and used only after endocrinologist consultation.

Further investigation

An infusion of 60 mL/kg/day of 10% dextrose is approximately 4 mg/kg/min of dextrose. Infusion rates of >10 mg/kg/min (150 mL/kg/day) with persisting hypoglycaemia should be regarded with some suspicion, and may be indicative of hyperinsulinism. Under these circumstances, investigations (at the time of hypoglycaemia) should include:

• Blood – glucose, insulin (±C-peptide), cortisol, pH, lactate, ketones, growth hormone, adrenocorticotrophic hormone (ACTH), acylcarnitine profile.

This can be achieved by collecting the following amounts of blood in the tubes indicated. The colours of blood specimen tubes will vary from hospital to hospital — always check.

Specimen type Tube colour
3 mL clotted blood red top
1 mL EDTA pink top
2 mL heparin green top

Also collect an ABG (arterial blood gas) in a blood gas syringe and spots of blood on a standard neonatal screening card. If you can, always collect a little extra for each type of tube.

• Urine — amino and organic acids — collect the first urine passed after the episode of hypoglycaemia. The urine should be sent fresh to the lab immediately after collection. Do not freeze.

One should always keep inborn errors of metabolism in mind because many infants present with hypoglycaemia with or without metabolic acidosis, ketosis, hyperammonaemia, hyperuricaemia, etc. Other investigations might include a serum amino acid profile, ammonia, free fatty acids and pyruvate.

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