Neonatal Hypoglycaemia

NEONATAL HYPOGLYCAEMIA A. Definition: Blood sugar < 2.6 mmol/L (approximately 45 mg/dl) in a term or premature infant.

B. Prevention and Early Detection Anticipation & prevention, when possible, are keys to the management of hypoglycaemia. Hypoglycaemia may produce long term neurological injury and the level at which it occurs is controversial. (i)

Identify all high-risk neonates Prematurity Hypothermia Sepsis Infant > 4 kg. Rhesus disease

Small for gestational age Birth Asphyxia / Perinatal Stress Infant of Diabetic Mother Polycythaemia

(ii)

Check glucometer/dextrostix on admission

(iii)

Immediate feeding for all well babies who are at risk. If hypoglycaemic on admission, repeat glucometer 1 hour later after feeding. Continue monitoring at 2 hours and 4 hours later. (i.e. O,1,2, 4 hours) If normoglycaemic on admission feed and monitor 6-8 hourly till past stage of hypoglycaemic risk

(iv)

Unwell babies (e.g. birth asphyxia or premature): set up a 10% dextrose drip. Monitor blood sugar Hourly X 2 Then 2 hourly X 2 Then 4 → 6 → 8 hourly until stable

(v)

Clinical features are: Symptoms are non-specific. For example: apathy, hypotonia, apnoea, poor sucking, cyanosis, abnormal cry, jitteriness, seizure, lethargy and temperature instability.

C. If Hypoglycaemia is detected 1.

Repeat the glucometer test. Send RBS stat for confirmation. (Note: monitoring using reagent strip measurement is quick, cheap and easy but not a precise method) Check expiry date of test stick!

2.

Is the infant symptomatic?

3.

When was the last feed given? Is the intravenous drip adequate and running well? (i.e. not disconnected or extravasated)

D. Asymptomatic Hypoglycaemia    

Feed early or bring forward next feed due. Feed 3 hourly. Recheck glucometer after 1 hour. If glucometer still < 2.6 mmol/L and child asymptomatic, can increase feeds if child can tolerate. Otherwise, Set up IV D 10% and give at least 72 ml/kg/day (5 mg/kg/min of glucose)

 Continue enteral feeds as tolerated.  Recheck glucometer hourly until stable and then 4-6 hourly.

E. Symptomatic Hypoglycaemia (Glucometer level immaterial) Give a bolus of 2 ml/kg of IV Dextrose 10% slowly . Follow-up by an infusion of glucose at 4-6 mg/kg/min (72ml/kg/day D10%) Keep nil by mouth Repeat glucometer after 1/2 to 1 hour and increase the infusion as necessary to 6-8 mg/kg/min (90 ml/kg/day D10%) If infection is suspected or there is no alternative explanation for hypoglycaemia take Blood C&S and treat as sepsis. Once the blood glucose normalised, feeds can be reintroduced gradually and infusion tailed off

F. If Hypoglycaemia persists Take Blood C&S and treat as sepsis if not done yet. Increase the rate of dextrose infusion if possible (i.e. do not increase beyond daily requirement). Increase the concentration of dextrose. Concentrations of 12.5% to 15% may be needed. If concentration of  12.5% is used, a central line is required If glucose infusion rates of more than 12mg/kg/min are required, hyperinsulinism should be seriously considered and investigated accordingly. Refer specialist Consider 1. Glucagon 0.2 mg/kg IV (IM) bolus 2. Hydrocortisone 2.5 -5 mg/kg/dose bd IV 3. Diazoxide 5 mg bd orally 4. Adrenaline 500 ng/kg/min IV infusion 5. Somatostatin 1 - 4 microgram SC. Also need to consider metabolic (See Approach to Hypoglycaemia under Metabolic section) and endocrine workup.

Key points: A.

Serial blood glucose should be routinely monitored in infants who have risk factors for hypoglycaemia

B

Bolus injections of large volumes of hypertonic glucose solutions should be avoided - dangerous to neurological function and may be followed by a rebound hypoglycaemia, cerebral oedema and is caustic to neonatal veins.

C

Milk formula provide more energy/ml than 10% dextrose and supply important nonglucose fuels, which have a glucose sparing role in neurological function. (Energy content of formula milk is 2750 kJ/l while that of 10% D is 1600 kJ/l). It promotes ketogenesis and gut maturation. Breast-feeding should be encouraged as it is more ketogenic.

D.

Milk feeds must not be discontinued or reduced when intravenous fluids are given unless the child develops NEC or other causes of feeding intolerance. The recommended practice is to feed the baby with as much milk as is tolerated and to infuse glucose at a rate sufficient to prevent hypoglycaemia. The IV glucose is then reduced slowly while milk feeds is maintained or increased. May need to continue over a few days.

E.

Ensure volume of intravenous fluid is appropriate for patient, taking into consideration concomitant problems like cardiac failure, cerebral oedema and renal failure. If unable to increase volume further, concentration of dextrose to be increased. Glucose requirement (mg/kg/min) =

% of dextrose x rate (ml/hr) x 0.167 ------------------------------------------------------wt (kg)

F.

Plasma glucose is 13-18% higher than whole blood glucose. Arterial blood has higher glucose concentration than venous blood. Capillary sampling can be unreliable in the presence of poor peripheral circulation.

G.

Requirement of >9mg/kg/min suggests hyperinsulinism. Truly hyperinsulinaemic babies may require 15-20 mg/kg/min

References Koh G Aynsley-Green A 1988a Neonatal hypoglycaemia- the controversy definition. Arch Dis Childhood;63:1386-1398 Koh G Aynsley-Green A Tarbit A Etre J 1988b Neural dysfunction during hypoglycaemia. Arch Dis Childhood;63:1353-1358 DK Pal et al 2000 Neonatal hypoglycaemia in Nepal. Prevalence and risk factors Arch Dis Childhood;82:F46-52 AA M Moris et al 1996 Evaluation of fast for investigating hypoglycaemia or suspected metabolic disease Arch Dis Childhood;75:115-119 th Gomella, Cunningham ,Eyal and Zenk: Neonatalogy 4 edition Lange