Biochemistry · Molecule
β-Hydroxybutyrate !
β-Hydroxybutyrate is the most abundant ketone body in blood; it is measured to diagnose and follow ketoacidosis.
Updated 2026-11-01
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Key facts
- Formed by reducing acetoacetate with NADH (BDH1); the physiological isomer is D (R).
- In fasting it is about 3 times more abundant than acetoacetate; in ketoacidosis, up to 10 times.
- Strictly it is not a ketone (it has a hydroxyl group), but it is grouped with the ketone bodies.
- Capillary blood measurement is the preferred way to monitor diabetic ketoacidosis.
- Also called
- D-3-hydroxybutyrate, (R)-3-Hydroxybutanoic acid
- Formula
- C₄H₈O₃
- PubChem
- CID 92135
Structure
- A 4-carbon acid with a hydroxyl at C3; negatively charged at physiological pH.
Clinical notes
- High β-hydroxybutyrate with a raised anion gap points to diabetic, alcoholic or starvation ketoacidosis.
- Besides fuel, it acts as a signal (inhibits histone deacetylases) and restrains lipolysis.
Pathways
Related conditions
Related
- Acetoacetate (acetoacetic acid)
- β-Hydroxybutyrate dehydrogenase (BDH1)
- Succinyl-CoA:3-ketoacid CoA transferase (SCOT)
- Mitochondrial HMG-CoA synthase (HMGCS2)
- NAD⁺ (nicotinamide adenine dinucleotide)
Test yourself
Think of the answer, then tap the question to see it.
What is the most abundant ketone body in diabetic ketoacidosis?
β-Hydroxybutyrate, because high NADH pushes the BDH1 reaction.
Why is blood β-hydroxybutyrate preferred to urine ketones?
The urine strip detects acetoacetate and can underestimate ketosis or track recovery poorly.
Is β-hydroxybutyrate chemically a ketone?
No: it is a hydroxy acid, although it is classed with the ketone bodies.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: 3-Hydroxybutanoic acid, (R)- (CID 92135) (PubChem, NCBI, 2026) · Public domain; Synthesis of Ketone Bodies (Reactome, 2026); Ketones blood test: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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