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Fluid Viscosity, Qualitative

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

This test checks whether a body fluid sample is viscous, meaning thick or sticky, which can give clues about its composition. It is a general qualitative assessment rather than a precise measurement.

Quick summary

["A fluid viscosity result describes how thick or sticky a sample appears, helping support other findings in your test results."]

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

Key facts at a glance

LOINC
54242-3
Short code
FLUV Islt
Synonyms
FLUV Islt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Being Tested

Viscosity is a property that describes how easily a fluid flows. A more viscous fluid is thicker and flows less readily. This qualitative test simply notes whether the fluid shows increased viscosity rather than reporting an exact numeric value.

Why the Test Is Done

Doctors may order this test when evaluating certain body fluids to see whether an unusually thick or sticky quality is present. Viscosity can reflect the makeup of the fluid, such as its protein or cell content, and can support the overall interpretation of a sample.

How the Sample Is Collected

A sample of the relevant body fluid is collected by your healthcare provider using a standard collection procedure for that fluid type. The sample is then examined in the laboratory for its physical characteristics.

What the Results Mean

Results are typically reported as a qualitative finding, such as whether increased viscosity is present or absent. Your healthcare provider interprets this result together with your symptoms, other laboratory tests, and the specific fluid being studied.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is this test a precise measurement of viscosity?
No. It is a qualitative assessment that describes whether the fluid appears viscous, not an exact numeric measurement.
Can I prepare for this test at home?
Preparation depends on the fluid being collected and your provider's instructions. Follow any directions you are given about eating, drinking, or timing before the sample is taken.
What happens if my result shows increased viscosity?
Increased viscosity is a finding that your provider will interpret alongside your symptoms and other tests. It does not by itself confirm a specific condition, so discuss the result with your healthcare provider.
  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