Immature platelet fraction (IPF) in hospitalized patients with neutrophilia and suspected bacterial infection.
OBJECTIVE
Neutrophilia is frequently in hospitalized patients, so a screening test for infections would be very useful. The immature platelet fraction (IPF) is provided by the automated blood analyzer XE 2100 (Sysmex, Kobe, Japan) as a proportional value of the total optical platelet count [IPF%; an absolute count of immature platelets can also be obtained (AIPC)] to indicate the rate of platelet production. IPF could help to identify the aetiology of thrombocytopenia and to recognize the increased bone marrow activity as occurred during the course of infectious disease.


METHODS
We selected from daily routine cell blood counts 535 samples from adult patients (age >14 years) with neutrophilia (> 8 x 10(9)/L) and platelets > or =150 x 10(9)/L, to avoid bias due to physiological increase of IPF. In 153 patients blood cultures (BC) were done the same day of IPF determination because of clinically suspected infection (fever > or =38 degrees C).


RESULTS
Eighty-nine samples (58.2%) had positive BC (75 Gram-positive agents, 14 Gram-negative). Using our IPF reference normal range [IPF% 2.39% (0.8-5.1); AIPC 5.15 x 10(9)/L (2-12.6)], we found a significantly (p<0.0001) higher level of IPF in samples with positive BC [mean IPF% 4.86+/-2.67%, median 3.8 (range 2.4-15.8); mean AIPC 14.74+/-9.26 x 10(9)/L, median 11.7, (range 4.7-44.9)] than in BC negative samples [mean IPF% 1.79+/-0.63%, median 1.7 (range 0.5-4.7); mean AIPC 6.55+/-3.58 x 10(9)/L, median 5.45 (range 1.6-20.4)].


CONCLUSIONS
The increased IPF shows a statistically significant correlation with BC positivity. This parameter could therefore be used in the daily laboratory routine in patients with neutrophilia as a low cost screening test for bacterial infection.
Di Mario
Antonella
A
Research Center for Clinical Evaluation of Automated Method in Hematology (ReCAMH), Hematology Department, Catholic University of Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy.
Garzia
Mariagrazia
M
Leone
Fiammetta
F
Arcangeli
Andrea
A
Pagano
Livio
L
Zini
Gina
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000302:isolation & purification; D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis*; D001784:Blood Gas Analysis; D005260:Female; D006760:Hospitalization; D006801:Humans; D007964:Leukocytosis / Q000150:complications* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D009504:Neutrophils; D010976:Platelet Count / Q000379:methods*; D018805:Sepsis / Q000097:blood; D013921:Thrombocytopenia / Q000209:etiology; D055815:Young Adult