Skip to content

Serum or plasma free mass concentration of salicylate

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

This test measures the amount of salicylate (a medication derived from willow bark) that is not bound to proteins in your blood, helping assess toxicity or therapeutic levels.

Quick summary

["Salicylate levels help monitor whether your medication dose is safe or if you may have an overdose."]

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

Key facts at a glance

LOINC
19205-4
Short code
PSA Free Smn-mCnc
Synonyms
PSA Free Smn-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
4
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84153
SNOMED
39392002
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

Why This Test Is Done

Your healthcare provider may order this test if you’ve taken salicylate-containing medications (like aspirin) for conditions like arthritis, fever, or pain. It’s also used in cases of suspected poisoning, especially in children or those with kidney issues, where salicylate can build up more easily.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, typically drawn from a vein in your arm. If you’re on salicylate medications, let your provider know before testing to avoid delays or adjustments.

What the Results Mean

High levels may indicate overdose, kidney problems, or improper medication use. Low levels could suggest the medication isn’t working as intended or you’re not absorbing it properly. Your provider will interpret results in the context of your symptoms and medical history.

Common Causes of Abnormal Results

Overdose from accidental ingestion, kidney disease, liver disease, or dehydration can raise salicylate levels. Insufficient medication, liver issues, or certain medications (like acetaminophen) may lower them.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Salicylate Level

Frequently asked questions

How long does it take to get results?
Results are usually available within 1–2 business days, depending on your lab’s processing time. Your provider will contact you once they’re ready.
Can I take my salicylate medication before the test?
If your test is scheduled, follow your provider’s instructions. Some may ask you to stop taking salicylate for a set period before testing to get an accurate reading.
Is there anything I should avoid before the test?
Avoid excessive alcohol or caffeine the day of testing, as they may affect lab results. Also, inform your provider about all medications, supplements, or recent illnesses.
  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