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Lymphoblasts, Whole Blood — Manual Count

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

A manual microscopic count of lymphoblasts (immature lymphoid cells) in a whole-blood sample, usually performed as part of a blood differential.

Quick summary

["This test checks a blood sample for immature lymphoid cells that may indicate a blood or lymph-node cancer."]

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

Key facts at a glance

LOINC
33831-9
Short code
Lymphoblasts NFr Bld Manual
Synonyms
Lymphoblasts NFr Bld Manual
Category
liver
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
CPT
84484
SNOMED
302774002
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 this test?

This test measures the presence and relative amount of lymphoblasts in whole blood. Lymphoblasts are immature white blood cells that normally develop into lymphocytes, a group of immune cells.

Why might I need this test?

A clinician may order this test when a blood count or blood smear suggests an abnormal number of immature cells. It can help evaluate suspected leukemia, lymphoma, or the response to treatment for a blood disorder.

How is the test performed?

A blood sample is collected, and a technician prepares a blood smear. The smear is examined under a microscope to identify and manually count lymphoblasts as part of the blood differential.

How do I prepare for the test?

No special preparation is usually required. Follow the laboratory's instructions, tell the staff if you have recently received chemotherapy or other treatment, and ask your clinician before stopping any medication.

Reference range

Adult: 10-40 U/LN/A

Specimen: whole-blood

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Manual blood lymphoblast count

Frequently asked questions

What are lymphoblasts?
Lymphoblasts are immature forms of lymphocytes, which are white blood cells that help fight infection. They are mainly made in the bone marrow and lymph nodes.
Does a manual count mean the test is less accurate?
No. Manual means a trained laboratory professional counts the cells by examining a blood smear under a microscope rather than using an automated cell counter. This allows direct identification of unusual cell types.
Does an abnormal result confirm leukemia?
No. Finding lymphoblasts in blood can raise concern for leukemia or lymphoma, but it does not establish a diagnosis by itself. Your clinician will interpret the result alongside other tests.
  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