This parameter is generated by the Full Blood Count analyser and is the sum of metamyelocytes, myelocytes and promyelocytes. It does not include band neutrophils.
Various studies have shown good correlation of the analyser Immature Granulocyte (IG) Count with the manual differential. This has been confirmed in our laboratory. The analyser count shows better reproducibility owing to the far larger number of cells counted. A reference interval of 0.0 - 0.06 x E+9/L for healthy adults has been established (Pekelharing et al.,2010) and is in the process of being implemented in New Zealand laboratories.
This parameter may be useful as an early alert for the presence of immature granulocytes before the unavoidable delay between analyser processing and blood film examination. The absence of a raised IG Count however does not preclude the presence of immature cells or a left shift.
Causes of a raised Immature Granulocyte Count include sepsis, inflammation, haematological or other malignancies, and conditions where there is a leucoerythroblastic picture.
In this laboratory the IG Count is a separate parameter reported outside the white cell differential which means the neutrophil count in the report will include these cells. If the only white cell abnormality is a raised IG Count then a manual differential will not be done. A manual differential will be performed and reported if there are significant numbers of band neutrophils, atypical (variant) lymphocytes, blast cells or other abnormal cells present. If a manual differential is performed Immature granulocytes will be identified and enumerated in the report as well as the analyser IG Count.
The procedure in this laboratory is for a FBC with a raised IG Count analyser flag (>=3% of total white cells) to have blood film examination the first time for clues as to the cause of the raised count. Thereafter blood film examination is not performed for a raised IG Count in isolation unless the previous count was more than 5 days ago. The IG Count is reported in all cases unless the analyser or blood film examination shows it to be false which may occur occasionally.
References:
Ali Ansari-Lari M., Kickler T. S., Borowtiz m. J. (2003) Immature Granulocyte Measurement Using the Sysmex XE-2100. American Journal of Clinical Pathology 2003; 120: 795-799
Bruegel M., Fiedler G.M., Matthes G., Thiery J. Reference values for Immature Granulocytes in Healthy Blood Donors generated on the Sysmex XE-2100 Automated Hematology Analyser. Sysmex Journal International 14: 5-7, 2004
Fernandes B., Hamaguchi Y. Automated Enumeration of Immature Granulocytes.
American Journal of Clinical Pathology 2007; 128: 454-463
Iddles C., Taylor J., Cole R., Hill FGH. Evaluation of the Immature Granulocyte Count in the Diagnosis of Sepsis using the Sysmex XE-2100 Analyser. Sysmex Journal International 17: 20-29, 2007.
Pekelharing J.M., Hauss O., de Jonge R., Lokhoff J., Sodikromo J., Spaans M., Brouwer R., de Lathouder S., Hinzmann R. Haematology Reference Intervals for Established and Novel Parameters in Healthy Adults. Sysmex Journal International 20: 15-23, 2010. re-published from ?Diagnsotic Perspectives? Vol 1 page 1-11.
Roehrl M. H. A., Lantz D., Sylvester C., Wang J. Y. Age-Dependent Reference Ranges for Automated Assessment of Immature Granulocytes and Clinical Significance in an Outpatient Setting. Arch Pathol Lab Med 135, 471-477, April 2011