Preferred Sample Type

3 Hydroxy Butyrate

3 Hydroxy Butyrate

Specimen Volume

1mL blood. Min.vol.100 uL plasma

Specimen Transport

Send sample on the first available transport

Sample Preparation

Centrifuge and send to reference laboratory ASAP.

Turnaround Time

2 weeks

Sample Processing In Laboratory

No special transport conditions.  Sample should be transported to laboratory asap

Sample Stability

Freeze plasma at -20 oC if not sent immediately.

General Information

The measurement of 3-hydoxy-butyrate is used together with free fatty acids (FFA) as a useful first line indicator of inherited defects of mitochondrial fatty acid catabolism. Ideally specimens should be taken during acute hypoglycaemic episodes or after a provocative fast. In most circumstances, as blood glucose falls, lipolysis and subsequently ketogenesis are stimulated; thus the plasma concentration of FFA and 3-hydroxybutyrate increase in an approximately equimolar fashion. In fatty acid oxidation defects, lipolysis will still be stimulated in response to a drop in blood glucose, but ketogenesis will be reduced. Therefore, a disproportionately high free fatty acid concentration relative to a low 3-hydroxy-butyrate concentration is found, particularly during periods of stress i.e. infection, coma, fasting and hypoglycaemia. In patients with hyperinsulinism, FFA and 3- hydroxybutyrate levels will both be low, as insulin suppresses lipolysis. This pattern will also be observed in patients with hypopituitarism, therefore this test can not be used to diagnose hyperinsulinism. However, hyperinsulinism can be ruled out by the demonstration of ketosis, i.e. elevated FFA and 3-hydroxy butyrate in the presence of hypoglycaemia. See for Best Practice Guidelines for the Investigation of Hypoglycaemia in Infants and Children.

Patient Preparation

Please supply glucose result and details of fasting.


None Given

Reference Range

Provided by reference laboratory.


  • EQA Status: Referral Laboratory participates in an EQA scheme
  • EQAS Scheme: Yes

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