OSCE viva practiceNeonatal hypoglycaemiaAAP 2011
A structured viva on screening and managing low glucose in an at-risk newborn. Answer each question out loud before you open the model answer, just as you would in front of an examiner.
Whether you know which babies to screen, can apply the age-specific thresholds, treat a symptomatic baby without delay, and recognise when low glucose is persistent.1
The scenario
A baby girl born at 35+4 weeks weighing 1.9 kg (small for gestational age) is on the postnatal ward with her mother. She is breastfeeding. The midwife calls you when she is 2 hours old to ask how her glucose should be managed.
Values are in mg/dL, as the AAP clinical report uses (18 mg/dL ≈ 1 mmol/L). Suggested time: 8–10 minutes.
01Which babies should be screened for low glucose, and which don’t need it?
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- Screen babies who are late preterm (34+0–36+6 weeks), small for gestational age, large for gestational age, or born to mothers with diabetes. This baby is both late preterm and SGA.1
- Check glucose within minutes, not hours, in any baby with signs that could be due to low glucose.1
- Healthy term babies after an entirely normal pregnancy and delivery don’t need routine screening.1
AAP 2011, “Which infants to screen”
02Talk me through her feeding and glucose checks over the first 24 hours.
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- Feed within the first hour, and check glucose 30 minutes after that first feed.1
- Birth to 4 hours: if the first check is below 25 mg/dL, feed and recheck in 1 hour. Still below 25 means IV glucose; 25–40 mg/dL means refeed or IV glucose as needed.1
- 4 to 24 hours: feed every 2–3 hours and check before each feed. Below 35 mg/dL, feed and recheck in 1 hour. Still below 35 means IV glucose; 35–45 mg/dL means refeed or IV glucose as needed.1
- The target is 45 mg/dL or more before routine feeds. As she is late preterm and SGA, checks continue for at least 24 hours, and beyond that if pre-feed values stay below 45. Consider gavage feeds if she isn’t feeding well.1
AAP 2011, “When to screen”, Management and Figure 1
03At 5 hours she is jittery and feeding poorly. Bedside glucose is 38 mg/dL. What do you do?
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- She has signs and a glucose below 40 mg/dL, so she needs IV glucose now.1
- Take a plasma sample for laboratory glucose just before treating, but don’t wait for the result.1
- Give a minibolus of 200 mg/kg (2 mL/kg of 10% dextrose) and/or start an infusion of 10% dextrose at 5–8 mg/kg/min (80–100 mL/kg/day). Aim for 40–50 mg/dL.1
- The signs aren’t specific, so look for other causes such as infection too, and keep checking glucose and reviewing her.1
AAP 2011, Clinical signs and Management
04How reliable is a bedside glucose, and how would you confirm it?
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- Test strips can be 10–20 mg/dL away from the true value, and the error is greatest at low values. No point-of-care method is reliable enough to be the only way of screening.1
- Confirm with an urgent laboratory test using an enzymatic method (glucose oxidase, hexokinase or dehydrogenase).1
- Send it in a fluoride tube. A delayed sample reads falsely low because red cells keep using up the glucose.1
- Plasma values run about 10–18% higher than whole-blood values.1
AAP 2011, Laboratory data
05On day 2 she can’t stay above 45 mg/dL on 8 mg/kg/min. What next, and what needs to happen before she goes home?
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- Think of hyperinsulinaemic hypoglycaemia, the leading cause of severe persistent hypoglycaemia in newborns.1
- Send insulin with a paired glucose when her bedside glucose is below 40 mg/dL, and involve an endocrinologist.1
- Before discharge she must keep normal glucose on a routine diet through at least 3 feed-fast cycles. This also helps pick up fatty acid oxidation disorders.1
AAP 2011, Management and Summary
06Why doesn’t the AAP give a single glucose value that defines hypoglycaemia?
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- No glucose level or duration has been shown to predict permanent brain injury.1
- Outcome studies are muddied by varying definitions, rarely reported duration, missing control groups, coexisting conditions such as hypoxia-ischaemia or infection, and small numbers of asymptomatic babies followed up.1
- The commonly used cut-off of below 47 mg/dL lacks rigorous scientific justification. So the report’s thresholds are pragmatic and set with a margin of safety above levels linked to clinical signs.1,2
AAP 2011, Introduction and Background
This AAP clinical report has expired and is under review. Its thresholds are pragmatic expert recommendations rather than trial-derived cut-offs. Always follow your local policy.1
References
- Adamkin DH; Committee on Fetus and Newborn. Postnatal Glucose Homeostasis in Late-Preterm and Term Infants. Pediatrics. 2011;127(3):575–579. doi:10.1542/peds.2010-3851
- Hay WW Jr, Raju TNK, Higgins RD, Kalhan SC, Devaskar SU. Knowledge Gaps and Research Needs for Understanding and Treating Neonatal Hypoglycemia. J Pediatr. 2009;155(5):612–617. doi:10.1016/j.jpeds.2009.06.044