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Platelet Count (Blood)

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

This test measures the number of platelets in your blood. Platelets are tiny cells that help your blood clot when you have a cut or injury.

Quick summary

["Platelets are crucial for preventing excessive bleeding."]

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

Key facts at a glance

LOINC
79427-1
Short code
Platelet #/area Bld HPF
Synonyms
Platelet #/area Bld HPF
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
150
Ref high
400
Critical range
50 N/A – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light-hpf
CPT
85049
SNOMED
900000000000003003
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

What Is a Platelet Count?

A platelet count is a simple blood test that checks how many platelets are in your blood. Platelets are essential for clotting, so low or high levels can affect how well your body stops bleeding or forms clots.

Why Might You Need This Test?

Doctors may order a platelet count to diagnose or monitor conditions like bleeding disorders, clotting disorders, infections, or certain cancers. It’s also used before surgeries or procedures that could cause bleeding.

How Is the Test Done?

A small blood sample is taken from your arm using a needle. The sample is sent to a lab where machines automatically count your platelets and other blood cells.

What Do the Results Mean?

Results are usually reported as a number of platelets per microliter (µL) of blood. Low platelet counts (thrombocytopenia) may indicate bleeding risks, while very high counts (thrombocytosis) could signal infections, inflammation, or other health issues.

Reference range

Adult: 150-400 x 10^9/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Platelet Count

Frequently asked questions

Why do I need this test if I don’t have symptoms?
Your doctor may recommend it as part of routine check-ups, before surgery, or if you’re taking medications that affect blood clotting, even if you feel well.
What are common causes of low platelet counts?
Low platelet counts can result from medications, autoimmune diseases, infections, or conditions like leukemia. Certain blood disorders or liver disease may also reduce platelet production.
How long does it take to get results?
Results are typically available within 1–2 business days, depending on your lab’s processing time.
  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