Arneth Count for Neutrophils: Principle, Procedure, and Clinical Significance
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Hematology

Arneth Count for Neutrophils: Principle, Procedure, and Clinical Significance

Arneth Count classifies neutrophils (N1–N5) by nuclear lobes. Detects left shift (infections) vs. right shift (anemia). Normal ranges for clinicians.

By Dayyal Dg.
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Hypersegmented Neutrophils
Blood smear with two hypersegmented neutrophils. WikiMedia / Ed Uthman

Arneth count, developed by Joseph Arneth, is a hematological method that classifies neutrophils into five stages (N1–N5) based on their nuclear lobe count. It determines the percentage of neutrophils with one (N1), two (N2), three (N3), four (N4), or five or more lobes (N5), reflecting their maturity. On the basis of nuclear lobes, neutrophils are grouped into stages N1, N2, N3, N4, and N5. A left shift (↑N1–N3) indicates infections (e.g., sepsis) or inflammation due to immature neutrophils, while a right shift (↑N4–N5) signals anemia (e.g., vitamin B12 deficiency) caused by excess mature cells.

Arneth Count for Neutrophils: Classification of Neutrophil Nuclear Lobe Stages with Diagrams and Normal Range Percentages.
StageNuclear LobesDiagramNormal Range
Stage I (N1) Nucleus is unilobed, typically appearing C- or U-shaped. Stage 1 Diagram 2–5%
Stage II (N2) Nucleus is bilobed, with two lobes separated by slender strands. Stage 2 Diagram 20–30%
Stage III (N3) Nucleus is trilobed, featuring three lobes divided by fine strands. Stage 3 Diagram 40–50%
Stage IV (N4) Nucleus is tetralobed, with four lobes separated by thin strands. Stage 4 Diagram 10–15%
Stage V (N5) Nucleus is pentalobed, with five distinct lobes and delicate intervening strands. Stage 5 Diagram 2–5%

Principle of Arneth Count

Neutrophils mature by increasing their nuclear segmentation. Younger cells (N1–N3) have fewer lobes, while older ones (N4–N5) are multilobed. Technicians examine Leishman/Wright-stained blood smears under oil immersion (100x). At least 100 neutrophils are counted in a zigzag pattern. If lobes are ambiguous, secondary markers are used:

  • Granule density: Younger cells have more granules.
  • Cell size: Neutrophils shrink with age.

Procedure

  1. Prepare a thin peripheral blood smear and stain with Leishman or Wright’s stain.
  2. Use low-power magnification to confirm even cell distribution.
  3. Under oil immersion (100x), count at least 100 neutrophils in a zigzag pattern and classify them into five stages (N1–N5) based on the number of nuclear lobes.
  4. Enter the counts in a table, calculate the percentage distribution for each stage, and optionally plot a graph to visualize maturation trends.
Graph Illustrating Percentage Distribution of Neutrophil Maturation Stages in Arneth Count
Graph showing neutrophil stage distribution in Arneth Count.

Clinical Significance of Arneth Count

The Arneth count is a hematological test that evaluates neutrophil maturity by categorizing cells according to the number of nuclear lobes. This assessment indirectly reflects bone marrow activity by distinguishing between younger and older neutrophils in circulation.

Shift to Left (Regenerative Shift)

When over 80% of neutrophils are classified as N1, N2, or N3 (indicating fewer lobes), it signifies a left shift.

  • Indicates: Increased neutrophil production bone marrow hyperactivity (young neutrophils released early).
  • Causes:
    • Acute infections (e.g., pneumonia, sepsis)
    • Tuberculosis
    • Inflammation, trauma, or hemorrhage
    • Exposure to irradiation

Shift to Right (Degenerative Shift)

When more than 20% of neutrophils fall into stages N4 and N5 (indicating more lobes), it denotes a right shift.

  • Indicates: Decreased neutrophil production and bone marrow hypoactivity (prolonged neutrophil maturation).
  • Causes:
    • Megaloblastic anemia (B12/folate deficiency)
    • Aplastic anemia
    • Septicemia
    • Chronic kidney/liver disease
    • Uremia

FAQs

  1. What is the Arneth count?

    The Arneth count is a historical hematology method developed by Joseph Arneth to classify neutrophils into five stages (1-5+ nuclear lobes), measuring cell maturity. A shift to the left (more immature cells) signals acute infections, while a shift to the right (hypersegmented cells) indicates chronic conditions like anemia. Though pivotal in early diagnostics, it is now replaced by automated analyzers.

  2. What is the Cooke-Arneth count?

    The Cooke-Arneth count refines Arneth’s original system with a nuanced scoring method for neutrophil nuclear segmentation. Like the Arneth count, it is obsolete, supplanted by modern automated hematology tools for precision and speed.

  3. Arneth count shift to the left vs. shift to the right.

    An Arneth count shift to the left denotes elevated immature neutrophils (band cells), typically seen in acute bacterial infections. A shift to the right reflects hypersegmented neutrophils (5+ lobes), linked to chronic diseases or vitamin deficiencies. Both patterns are now detected via automated analyzers, not manual counts.

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Reference(s)

  1. Pal, Gopal Krushna. “Textbook Of Practical Physiology.” 2nd ed., Orient BlackSwan, 2008, isbn: 9788173716348.
  2. Khurana, Indu. “Textbook Of Medical Physiology.”, Elsevier India, 2005, isbn: 9788181478504.

Cite this page:

Dayyal Dg.. “Arneth Count for Neutrophils: Principle, Procedure, and Clinical Significance.” BioScience. BioScience ISSN 2521-5760, 27 February 2025. <https://www.bioscience.com.pk/en/topics/hematology/arneth-count-for-neutrophils-principle-procedure-and-clinical-significance>. Dayyal Dg.. (2025, February 27). “Arneth Count for Neutrophils: Principle, Procedure, and Clinical Significance.” BioScience. ISSN 2521-5760. Retrieved March 03, 2025 from https://www.bioscience.com.pk/en/topics/hematology/arneth-count-for-neutrophils-principle-procedure-and-clinical-significance Dayyal Dg.. “Arneth Count for Neutrophils: Principle, Procedure, and Clinical Significance.” BioScience. ISSN 2521-5760. https://www.bioscience.com.pk/en/topics/hematology/arneth-count-for-neutrophils-principle-procedure-and-clinical-significance (accessed March 03, 2025).
  • Posted by Dayyal Dg.

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