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Whole Body Tumor Localization with Fluorodeoxyglucose Positron Emission Tomography (FDG-PET)

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

This test uses a special dye (fluorodeoxyglucose, or FDG) to help doctors identify areas of high metabolic activity, often linked to cancerous tumors, throughout your entire body.

Quick summary

Helps detect cancer spread or recurrence that may not show up on other imaging tests alone.

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

Key facts at a glance

LOINC
81555-5
Short code
PT+CT Whole body Tum loc W 18F-FDG IV
Synonyms
PT+CT Whole body Tum loc W 18F-FDG IV
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
pt-ct
CPT
85610
SNOMED
396252006
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

How the Test Works

You’ll receive a small injection of FDG, a radioactive sugar that your body absorbs. A special camera scans your body to detect where the FDG has accumulated, highlighting areas with high metabolic activity, which may indicate tumors or other abnormalities.

Preparation

No special preparation is needed, but you may be asked to fast for a few hours before the scan to ensure accurate results. Wear comfortable clothing without metal fasteners.

What to Expect During the Test

You’ll lie still on a table while the scanner moves around your body. The scan takes about 60 minutes, and you may need to stay still for short periods. You’ll be asked to drink water and rest afterward to help your body clear the FDG.

Possible Risks and Side Effects

The risks are generally low. Possible side effects include mild discomfort from the injection, temporary redness or swelling at the injection site, or mild allergic reactions. You may feel tired afterward, so plan to rest.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: whole-blood

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Frequently asked questions

Why was I asked to have this test?
Your healthcare provider may recommend this test if you have symptoms of cancer, such as unexplained weight loss, fatigue, or pain, or if you’re being evaluated for cancer recurrence or treatment response. It can also help identify areas of concern in your body that may need further investigation.
What does a positive result mean?
A positive result means areas of high metabolic activity were detected, which may indicate the presence of tumors or other abnormal growths. However, these findings must be confirmed with additional tests or biopsies by your doctor to determine the exact cause.
How often will I need this test?
The frequency depends on your medical condition and treatment plan. Your doctor will determine how often you need follow-up scans based on your individual needs, such as monitoring cancer progression or response to treatment.
  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