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Serum β-Hydroxybutyrate (β-Hydroxybutyrate, Ketoacid)

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of β-hydroxybutyrate, a ketone body produced when your body breaks down fat for energy, often seen in conditions like diabetic ketoacidosis or fasting states.

Quick summary

["β-Hydroxybutyrate helps assess metabolic balance and identify elevated ketone levels that may require medical attention."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
38493-3
Short code
Ketones Titr SerPl
Synonyms
Ketones Titr SerPl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

When and Why It’s Done

Your healthcare provider may order this test if you have symptoms like excessive thirst, frequent urination, nausea, or unexplained weight loss. It’s also used in monitoring conditions like diabetes, fasting, or metabolic disorders. Sometimes, it’s part of a broader metabolic screening.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a fasting metabolic panel. Bring any medications you’re currently taking to your appointment.

How the Test Works

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure β-hydroxybutyrate levels using a specialized method, often an enzymatic technique.

What the Results Mean

High levels of β-hydroxybutyrate may indicate conditions like diabetic ketoacidosis, starvation, or excessive alcohol consumption. Low levels could suggest malnutrition or certain metabolic disorders. Your results will be interpreted by your healthcare provider in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

β-Hydroxybutyrate (Serum)

Frequently asked questions

Why might my doctor ask for this test?
Your doctor may request this test to check for abnormal ketone levels, especially if you have symptoms like fatigue, confusion, or rapid breathing. It’s also useful during pregnancy, in cases of unexplained weight loss, or when managing conditions like diabetes.
What are typical reference ranges?
Reference ranges vary by lab and individual health status. Normal levels are generally below 0.5 mmol/L, but higher values may indicate metabolic stress. Your healthcare provider will provide your specific results and explain what they mean for you.
Can I eat or drink before this test?
If fasting is required, avoid food and liquids (except water) for 8–12 hours before the test. If no fasting is needed, follow your doctor’s instructions. Always check with your provider before making dietary changes.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy