Immature Granulocytes: Normal Range and High Results
Medically reviewed by Dr. Michael Teplitsky, MD Last reviewed 2026-10-12
What automated immature granulocyte counts and percentages indicate on a complete blood count
Immature granulocytes are young white blood cell precursors that automated analyzers count during a complete blood count (CBC). A high result is not specific to any single condition, because elevated counts occur with bacterial infections, chronic inflammation, acute bleeding, hemolysis, tissue damage, and bone marrow disorders. When a test flags these early cells, clinicians interpret the number alongside your overall blood panel and physical symptoms.
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Immature granulocytes (IGs) are white blood cell precursors. An automated IG count represents the sum of three distinct precursor stages: promyelocytes, myelocytes, and metamyelocytes.
In bacteremia, immature granulocytes are recruited into circulation. This is described as a 'shift to left' in the bone marrow's response to bacterial infection.
Some automated analyzers measure IG% by flow cytometry. A 2012 evaluation in Automated measurement of immature granulocytes (PMC, 2012) found that automated counts may offer better precision, turnaround time, and accuracy than manual band counts. That study observed that manual counting consistently underestimated immature granulocytes at low counts.
Reading an Immature Granulocyte Result
Reference values for immature granulocytes vary depending on the analyzer manufacturer, patient age, and the specific laboratory processing the sample.
Published studies report these ranges:
| Source | IG% | Absolute count |
|---|---|---|
| Healthy blood donors (cited in the 2012 paper) | 0 to 0.4% | Not given |
| Outpatient age 10 or younger (cited in the 2012 paper) | Upper limit 0.30% | 40.0 per microlitre |
| Outpatient older than 10 years (cited in the 2012 paper) | Upper limit 0.90% | 70.0 per microlitre |
| 2021 study (115 controls) | 0 to 0.63% | 0 to 0.06 ×10⁹ per litre |
The 2021 study of 115 controls is described in Reference range for the immature granulocytes parameter (PubMed). The authors of the 2012 paper explained that a reference interval for children could not be defined due to practical difficulties. They said each institution should establish its own reference interval wherever possible. Compare your result directly with the reference interval listed on your laboratory report.
What a High Result Can Mean
According to a 2024 study in Clinical utility of automated immature granulocyte measurement (PMC, 2024), a rise in immature granulocytes is not specific to bacterial infection alone.
Clinicians observe elevated immature granulocytes across a broad spectrum of medical circumstances:
- Bacterial infections and bacteremia
- Chronic inflammatory diseases
- Tissue damage
- Acute hemorrhage (bleeding)
- Hemolysis (the breakdown of red blood cells)
- Neoplastic disorders and myeloproliferative neoplasms
- Metabolic abnormalities and seizures
- Certain medications
In the 2024 single-centre investigation of 100 adults with positive blood cultures and 100 adults with negative blood cultures, the mean IG% was 1.935% in culture-positive patients versus 0.386% in culture-negative individuals. In that cohort, 37 of the 100 culture-positive patients had an IG% of 2% or higher, whereas zero culture-negative patients reached that level. The researchers excluded pregnant patients, immunocompromised individuals, those taking antibiotics or steroids, and patients with hematologic malignancies. The 2012 study authors noted that the purpose of automated IG parameters is to screen for bacteremia rather than to diagnose it. Their ability to discriminate was modest (AUC 0.6 to 0.7).
How the CBC Reports It
Some analyzers report the IG count (IGC), the absolute figure, and IG%, the immature granulocyte percentage, on a CBC with differential.
The procedure involves taking a blood sample from a vein in the arm with a small needle, usually under five minutes. The test involves very little physical risk and requires no special preparation before your appointment.
What to Do With Your Result
As MedlinePlus notes, abnormal results don't always mean a condition that needs treatment. Your healthcare provider evaluates your laboratory metrics alongside your medical history, current symptoms, and other tests. Physical injury, extreme stress, smoking and alcohol use can affect results.
Our blood test results guide covers lab results more broadly; a licensed clinician can interpret yours.
Where to Find CBC Test Kits
Many labs and direct-to-consumer services let you order a CBC (complete blood count) test without a doctor's visit. If you'd rather compare kits yourself, here's where to start looking:
- At-home CBC (complete blood count) test kits on Amazon — compare brands, prices, and Prime shipping.
Frequently Asked Questions
What are immature granulocytes?
Immature granulocytes are white blood cell precursors, specifically promyelocytes, myelocytes, and metamyelocytes. Some automated analyzers report these cells as an IG count and IG% on a CBC with differential.
What does it mean if immature granulocytes are high?
A high count is not specific to one condition. In bacteremia, immature granulocytes are recruited into circulation, which indicates an active bone marrow response. Raised counts also occur with chronic inflammation, acute bleeding, hemolysis, tissue damage, seizures, metabolic abnormalities, certain medications, and myeloproliferative neoplasms.
Is a high immature granulocyte count a sign of cancer?
A high count is not a diagnosis of cancer. While neoplastic disorders and myeloproliferative neoplasms can increase immature granulocytes, non-malignant conditions like bacterial infections, tissue injury, and chronic inflammation also raise these numbers. A physician evaluates the finding alongside other blood markers.
What is a normal immature granulocyte range?
Studies of healthy blood donors reported relative counts between zero and 0.4%, and a 2021 study of 115 controls reported 0 to 0.63%. Ranges vary by laboratory and analyzer, so use the interval printed on your own report.
Do immature granulocytes always mean infection?
No, immature granulocytes do not always indicate an infection. While clinical teams use automated parameters to screen for bacteremia, elevated levels also occur from tissue damage, acute bleeding, hemolysis, medications, seizures, and chronic inflammatory conditions.
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