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Protein-Bound Valproate, Serum/Plasma — Mass Concentration

Published: August 9, 2026Updated: August 17, 2026

Measures the portion of valproate, also called valproic acid, that is bound to blood proteins. It may help interpret valproate levels when protein binding is altered.

Quick summary

["This blood test measures the protein-bound portion of valproate and is most useful when binding or total valproate levels may be difficult to interpret."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
18489-5
Short code
PB Valproate SerPl-mCnc
Synonyms
PB Valproate SerPl-mCnc
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
44
Ref high
147
Critical range
— – 151 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84075
SNOMED
27550007
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

What is this test?

Valproate, also called valproic acid, is a medicine used to treat seizures and certain mood disorders. Much of it travels in the blood attached to proteins, especially albumin. This test measures the amount of valproate that is protein-bound.

Why might I need this test?

Your clinician may order this test to better understand valproate exposure when the total valproate level is difficult to interpret. Blood protein levels, liver function, pregnancy, and other factors can change how much valproate remains bound to proteins.

How is the test performed?

A blood sample is drawn from a vein and sent to a laboratory for analysis. The result is typically reported as the mass concentration of protein-bound valproate in the sample.

How do I prepare for the test?

Fasting is usually not required. Because valproate levels can change after a dose, the blood sample may need to be collected at a specific time and in relation to your last dose. Follow your clinician's timing instructions and do not change or stop your medication without medical advice.

Reference range

Adult: 44-147 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Protein-bound valproate

Frequently asked questions

Is protein-bound valproate the same as a total valproate level?
No. The total valproate level includes both protein-bound and unbound valproate, while this test measures only the protein-bound portion.
Why can a low albumin level affect this result?
Albumin is the main blood protein that binds valproate. If albumin is low, less valproate may be bound even when the total amount in the blood is adequate.
Can the doctor change my dose based on this result alone?
Usually not. Your clinician will consider the protein-bound result along with your total valproate level, albumin level, symptoms, and medication history before making any dosing 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 17, 2026. · Read our editorial policy