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Platelet Count (Automated Optical Counting Method)

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

This test measures the number of platelets in your blood, a key part of your blood’s ability to clot and prevent excessive bleeding.

Quick summary

["Platelets help stop bleeding and prevent clots; low or high counts may signal health concerns."]

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

Key facts at a glance

LOINC
97994-8
Short code
Lg Platelets NFr Bld Auto Optical
Synonyms
Lg Platelets NFr Bld Auto Optical
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
automated-count-optical
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

Why This Test Is Done

Doctors order platelet counts to check for bleeding disorders, infections, or conditions like leukemia. It’s often done after trauma, surgery, or if you have symptoms like easy bruising or prolonged bleeding.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. The test is quick and usually painless.

What the Results Mean

Results are reported as the number of platelets per microliter (µL) of blood. While reference ranges vary by lab, very low counts (thrombocytopenia) may raise concerns about bleeding risks, while very high counts (thrombocytosis) may signal inflammation or clotting issues.

Common Conditions Affecting Platelets

Low platelet counts can result from medications (e.g., certain chemotherapy drugs), autoimmune diseases, liver problems, or infections. High counts may occur with infections, inflammation, or blood loss.

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 Blood Count (Auto-Optical)

Frequently asked questions

What causes low platelet counts?
Low platelet counts (below normal) can lead to increased bleeding risk, bruising, or nosebleeds. Causes include bone marrow disorders, certain medications, or conditions like autoimmune diseases or liver disease.
How long does it take to get results?
Results are typically available within 1–2 business days, depending on your lab. Follow-up with your doctor if you have questions about your results.
Can I eat or drink before this test?
Yes, you can eat and drink normally before the test. No fasting is required.
  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