Skip to content

Valproate Trough, Serum/Plasma — Mass Concentration

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

Measures the amount of valproate in your blood at its lowest point, usually just before the next dose. This helps your clinician determine whether your medication level is appropriate.

Quick summary

["A valproate trough level is a blood test that shows how much valproate is in your blood at the lowest point before your next dose."]

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

Key facts at a glance

LOINC
4088-1
Short code
Valproate Trough SerPl-mCnc
Synonyms
Valproate Trough 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?

This test measures the concentration of valproate, also called valproic acid, in your blood. A trough level is generally collected near the end of the dosing interval, shortly before the next dose, when the amount of medication in your blood is expected to be lowest.

Why might I need this test?

Your clinician may order this test to check whether your valproate dose is appropriate, particularly if you have seizures, mood symptoms, or side effects. It can help assess medication absorption, adherence, and possible interactions with other medicines.

How is the test performed?

A blood sample is drawn from a vein and sent to a laboratory for analysis. The result is reported as the amount of valproate in the blood, together with the collection time and, when available, the timing of your last dose.

How do I prepare for the test?

Take valproate exactly as prescribed and do not skip or change doses unless your clinician tells you to. Because this is usually a trough test, ask your healthcare team whether the sample should be collected shortly before your next dose and record the time of your last dose.

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

Valproate Trough Level

Frequently asked questions

What is a valproate trough level?
It is the amount of valproate in your blood at its lowest expected level, usually measured shortly before your next dose. It is used to help assess how your body is handling the medication.
When should the blood sample be collected?
The sample is typically collected as close as possible to the time of your next dose, according to your clinician's instructions. Tell the laboratory when you took your last dose.
Does an abnormal result mean I should change my dose?
Not necessarily. Your clinician will interpret the level together with your symptoms, dose, other medicines, and laboratory results before making any treatment changes. Do not adjust or stop valproate without medical guidance.
  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