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Serum/plasma concentration of homocysteine (total)

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

This test measures the amount of homocysteine, an amino acid, in your blood. It helps assess risks related to blood vessel health and certain genetic conditions.

Quick summary

["Homocysteine levels can indicate potential heart or blood vessel problems."]

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

Key facts at a glance

LOINC
49279-3
Short code
LDH Isos SerPl-Imp
Synonyms
LDH Isos SerPl-Imp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
140
Ref high
280
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83615
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms of vascular disease (like leg pain or fatigue), a history of heart disease, kidney problems, or if you’re taking folic acid or vitamin B supplements. It may also be checked as part of routine screening for genetic conditions affecting metabolism.

What Does the Result Mean?

Higher-than-normal levels may suggest increased risk of blood clots, heart disease, or nerve damage. Lower levels might indicate folate or vitamin B deficiency. Results alone don’t diagnose a condition—they’re used alongside other tests and symptoms.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The blood is processed to separate serum or plasma, then analyzed for homocysteine levels using a specialized immunoassay method.

What Are Common Causes of Abnormal Results?

Elevated levels can be linked to kidney disease, certain medications (like chemotherapy drugs), or genetic factors. Low levels may result from deficiencies in folate, vitamin B6, or B12.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Homocysteine as a Vascular Risk Marker

Short name

Total Homocysteine

Frequently asked questions

How often should I get this test?
This test isn’t routinely recommended for all adults, but your provider may suggest it if you have risk factors like diabetes, high blood pressure, or a family history of heart disease. Follow-up timing depends on your individual health plan.
Can I eat or drink before the test?
Typically, fasting isn’t required, but always follow your provider’s instructions. Avoid alcohol for 24 hours before testing if advised.
What do I do if my results are out of range?
If your levels are high, your provider may recommend lifestyle changes (like diet or exercise), supplements, or further testing to check for underlying causes. If low, they may suggest vitamin checks or adjustments to your diet.
  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