Absolute Basophil Count

Unit Converter
Basophils (Absolute basophil count)

(Basophil Count – Granulocyte Subtype – Allergic & Myeloproliferative Marker)

Synonyms

Basophils
Absolute basophil count (ABC)
Baso count
Basophil granulocytes
Basophilia (if high)
Basopenia (if low)

Units of Measurement

10^9/L, G/L, Gpt/L, cells/L, 10^3/µL, 1000/µL, 10^3/mm^3, 1000/mm^3, k/µL, k/mm^3, cells/µL, cells/mm^3

Description

Basophils are the least abundant white blood cells, representing <1% of circulating leukocytes.
They are granulocytes involved in:

Allergic responses
Hypersensitivity reactions
Release of histamine, heparin, leukotrienes
Immune modulation

The absolute basophil count = total number of basophils per unit volume of blood, not percentage.

Basophil counts help in evaluating:

Myeloproliferative neoplasms (MPN)
Allergic and inflammatory disorders
Chronic infections
Endocrine and immune diseases

Physiological Role

Basophils contain granules with:

Histamine → vasodilation, increased vascular permeability
Heparin → anticoagulant
Eosinophil chemotactic factor
Leukotrienes (LTC4) → bronchoconstriction

They participate in:

Type I hypersensitivity
Parasite immunity
Modulating Th2 responses

Clinical Significance

Elevated Basophil Count (Basophilia)

Most important clinical marker → Myeloproliferative Neoplasms (MPN)

1. Chronic Myeloid Leukemia (CML) - hallmark

Basophils often markedly increased.

2. Other Myeloproliferative Neoplasms

Polycythemia vera
Primary myelofibrosis
Essential thrombocythemia

3. Allergic / Hypersensitivity Conditions

Chronic urticaria
Atopic dermatitis
Asthma
Food allergy

4. Chronic Inflammation

Ulcerative colitis
Rheumatoid arthritis
Chronic infections

5. Endocrine Disorders

Hypothyroidism
Estrogen therapy

Low Basophil Count (Basopenia)

Seen in:

Acute infections
Hyperthyroidism
Stress reactions
Pregnancy
Long-term steroids, Cushing syndrome
Severe allergies (early phase)

Basopenia has limited clinical value unless part of broader leukopenia.

Reference Intervals

(Tietz 8E + ISLH + ASH hematology reference)

0 – 0.10 × 10^9/L
0 – 100 × 10^6/L
0 – 100 cells/µL

Typical normal values:

< 0.02 × 10^9/L in most healthy individuals
< 1% of total WBC count

Basophilia

> 0.10 × 10^9/L or > 100 cells/µL
Persistent basophilia → suspect CML until proven otherwise

Unit Meanings

Unit	Meaning
10^9/L	billions per liter
G/L or Gpt/L	gigacells per liter = 10^9/L
cells/L	absolute count per liter
10^3/µL = 1000/µL	thousands per microliter
k/µL	thousands per microliter
10^3/mm^3 = k/mm^3	thousands per cubic millimeter
cells/µL / cells/mm^3	absolute number per microliter/mm³

Diagnostic Uses

1. Screening for Hematological Malignancy

Basophilia is a strong indicator of:

CML
MPN spectrum disorders
Leukemoid reactions

2. Allergy & Hypersensitivity Assessment

Particularly chronic allergic states.

3. Monitoring Drug Reactions

Certain medications increase basophils:

Penicillin
Antihypertensives
Estrogens

4. Chronic Inflammatory or Autoimmune Disease

Basophil count correlates with long-term inflammation.

5. Endocrine Evaluation

Thyroid abnormalities alter basophil count.

Analytical Notes

Derived from automated hematology analyzers (flow cytometry + scatter).
Manual differential rarely needed.
Pre-analytical issues:
- Clotted samples → falsely low WBC
- EDTA samples stable for 24 hours
Severe allergies: early depletion → basopenia, followed by rebound basophilia.

Clinical Pearls

Persistent basophilia = CML until proven otherwise.
Basophils are part of the “triple-lane” granulocyte series (neutrophils, eosinophils, basophils).
Always interpret alongside WBC, eosinophils, platelets, and hemoglobin.
Hypothyroidism often shows mild basophilia; hyperthyroidism → basopenia.
Basophil % is less meaningful than the absolute basophil count (ABC).

Interesting Fact

Basophils are immunologically similar to mast cells, sharing histamine-rich granules - but basophils circulate in blood, while mast cells reside in tissues.

References

Tietz Clinical Chemistry and Molecular Diagnostics, 8th Edition - Hematology Indices.
ISLH Hematology Standards - WBC Differentials.
ASH (American Society of Hematology) - Basophilia Guidelines.
Mayo Clinic Laboratories - Basophil Count.
ARUP Consult - CBC Interpretation.
MedlinePlus / NIH - White Blood Cell Types.
Hematology Textbooks - Myeloproliferative Disorders.