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Immature Granulocytes (Absolute)

The number of young white blood cells (immature granulocytes) in a microliter of blood. Most healthy adults have very few.

AI-verified against cited sources. Awaiting expert reviewAlso called IG#, IG Abs, IG (abs)LOINC 53115-2

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What it is

Granulocytes are white blood cells that help fight infection. They start out as young cells in your bone marrow and mature before they enter the blood. Immature granulocytes (IGs) are the younger forms. On Labcorp reports, the IG count includes metamyelocytes, myelocytes and promyelocytes, and it does not include bands or blast cells. Many automated analyzers report IGs as part of a CBC with differential, and other labs may define the count slightly differently. A healthy adult usually has very few IGs in the blood.

Why it matters

Because so few IGs reach the blood in healthy adults, a higher count shows that the bone marrow is releasing young cells faster than usual. This is most often a reaction to infection, inflammation, pregnancy or a medicine such as a steroid. Less often it can be linked to a bone marrow or blood condition, which is why labs sometimes look at the blood smear under a microscope. If the count is only mildly raised and the rest of your blood count is steady, your clinician may simply repeat the test.

If it’s high

A higher count means more young granulocytes than usual are in your blood. It is most often a reaction to something else, such as an infection, pregnancy or a medicine. In one large outpatient study, the reasons for a raised IG count in people over 10 included severe infections, pregnancy, steroid or chemotherapy medicines, and blood cancers. In children it was mostly infections. Your clinician will read the count together with the rest of your blood count and your health.

Common causes

  • Infection (in children, the most common finding)
  • Pregnancy, especially in younger women
  • Steroid (glucocorticoid) medicines or chemotherapy
  • Inflammation or other physical stress on the body
  • Blood or bone marrow conditions (one reason a lab may look at a blood smear if the count stays high)

What can help

  • Ask whether your blood count should be repeated, especially if you were sick or pregnant when it was drawn
  • Ask whether a medicine you take, such as a steroid, could be the reason
  • If the count stays high, ask whether your lab can look at a blood smear

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on age. Choose an age to see the one that applies.

Children and teens 7 ranges

See IG (abs) by age and sex, with the U.S. survey numbers where they exist.

What can affect your result

  • Age: newborns and babies normally have more IGs than adults
  • Pregnancy
  • Infection or inflammation around the time of the blood draw
  • Steroid medicines and chemotherapy
  • The analyzer and lab: each defines and counts IGs a little differently
  • Whether bands and blast cells are counted on separate lines
  • Different analyzers and labs define and count immature granulocytes a little differently, so compare results from the same lab when you can.
  • Infection, pregnancy, and steroid or chemotherapy medicines can raise the count.
  • A clotted, old or poorly mixed sample can throw off any automated count. The lab may repeat the count or look at a blood smear under the microscope.

The count can change within days as an infection or other cause comes and goes.

When to talk to a clinician

A result above your lab's range is worth mentioning to the clinician who ordered it, but it is rarely urgent by itself. Check in sooner if it stays high on a repeat test, or if you also have a fever of 38.0°C (100.4°F) or higher, bruising or bleeding you cannot explain, or drenching night sweats. Call 911 or your local emergency number for chest pain, trouble breathing, confusion or fainting.

Questions you could ask

  • How does my lab define immature granulocytes on this report?
  • Could an infection, pregnancy or a medicine explain a higher IG count?
  • Should we repeat my blood count, and when?
  • Does my lab look at a blood smear when the IG count is high?

Questions people ask

What is the difference between immature granulocytes and bands?

Both are young white blood cells. Bands are one step from fully mature cells and are usually counted on their own line. Labcorp's report note says its IG count is metamyelocytes, myelocytes and promyelocytes, and does not include bands or blast cells. Your lab's definition may differ, so check the note on your report.

My IG count is flagged high. Should I be worried?

A flag means the number is above your lab's range. It does not mean something is wrong. Infection, pregnancy and steroid medicines can all raise it for a while. It is worth mentioning to your clinician, who can look at the rest of your blood count and decide whether a repeat test makes sense.

Why does my report show IG as a percent and as a count?

The percent is the share of your white blood cells that are IGs. The count is how many there are in a microliter of blood. The count is usually the more useful number, because the percent can shift when your total white blood cell count changes.

Show the science and sources

Units

  • 1 ×10³/µL = 1 ×10³/µL
  • 1 ×10³/µL = 1 ×10⁹/L
  • 1 ×10³/µL = 1000 cells/µL

Open the IG (abs) unit converter

For clinicians and researchers

Hematology analyzers report immature granulocytes (IG) as a count and a percent of white cells. Labcorp's footnote defines the IG count as metamyelocytes, myelocytes and promyelocytes, without bands or blasts. Definitions and limits depend on the analyzer, the population and age. Published adult limits include ARUP 0.01–0.09 ×10³/µL (0.2–0.9%), Labcorp 0.0–0.1 ×10³/µL, a healthy-donor study on one analyzer 0–0.06 ×10⁹/L (0–0.63%), and an indirect hospital-data study on a Sysmex XN-1000 0.01–0.04 ×10⁹/L (0.10–0.60%). In more than 2,400 outpatient samples, the 95th percentile was about 30/µL up to age 10 and about 60/µL above 10, with no sex difference, and the authors suggested upper limits of 40/µL (0.30%) and 70/µL (0.90%). Another hospital laboratory lists 0.0–0.5 ×10³/µL. Labs use the IG flag to decide which samples need a manual smear review. Limits are much higher in the first days of life (ARUP 0.08–1.68 ×10³/µL at 0 to 2 days) and fall through childhood. No published critical value was found.

LOINC 53115-2 (primary), 51584-1. Specimen: whole-blood.

Sources

  1. CBC with Diff, Platelet, NLR, sample patient report (test 005013), Labcorp
  2. CBC With Differential/Platelet, sample patient report (test 005009), Labcorp
  3. CBC with Platelet Count and Automated Differential (test 0040003), hotline effective March 1, 2021, ARUP Laboratories (2021)
  4. Complete Blood Count (CBC) with Automated Differential (MHCC Laboratory, test CBCD), MHCC Laboratory (catalog powered by Mayo Clinic Laboratories)
  5. Age-dependent reference ranges for automated assessment of immature granulocytes and clinical significance in an outpatient setting, Archives of Pathology & Laboratory Medicine (2011)
  6. Definition of Reference Range for the Immature Granulocytes Parameter Provided by a Hematology Analyzer, Clinical Laboratory (2021)
  7. Local reference intervals for MacroR, MicroR, IG% and IG# on Sysmex XN-1000: A retrospective indirect LIS-based study, Medicine (Baltimore) (2026)
  8. Pediatric Testing Reference Ranges, Labcorp

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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