Evaluation of platelet parameters in pediatric oncology patients undergoing myelotoxic chemotherapy.

Introduction: Due to the high-intensity treatment especially in pediatric oncology thrombocytopenia is often associated with the necessity of platelet transfusions (PT). So far, transfusion decisions are mainly based on platelet count (PC). Laboratory automatic counters can easily measure PC but also other platelet parameters such as relative (IPF%) and absolute (IPF#) immature platelet fraction, mean platelet volume (MPV), plateletcrit (PCT), platelet distribution width (PDW) and platelet-large cell ratio (P-LCR). We investigated the dynamics of these platelet parameters in children with malignancies during and after polychemotherapy aiming whether these parameters can reliably predict the rise of PC after reaching the platelet nadir (PN) and therefore can contribute to the indication for PT.

Method: A total of 32 patients (age: 9 months - 16 years; median: 4.0 years) with 68 cycles of chemotherapy were included. Platelet parameters were determined in EDTA blood using the hematology analyzer Sysmex-XN. Ten children suffered from solid tumors (neuroblastoma (n=3), osteosarcoma (n=3], astrocytoma [n=1], Ewing sarcoma [n=1], clear cell sarcoma [n=1], rhabdomyosarcoma [n=1) and 22 children had acute lymphoblastic leukemia (ALL, n=20) or lymphomas (B-cell n=1, T-cell n=1). Measurements were performed before chemotherapy (Day 0) und on Days 2 to 4, 5 to 7, 8 to 10 etc. until platelet recovery (PR), defined as a rise of PC to≥50 x 10⁹/L after reaching the lowest PC (PN) without prior PT.

Results: IPF% and MPV in patients with solid tumors, and PDW and P-LCR in both groups, increased from Day 0 until PN and then decreased until PR. In leukemia and lymphoma patients, IPF% and MPV increased from Day 0 until PN and continued rising until PR. IPF# and PCT decreased with PC from Day 0 until PN, then increased until PR. Between the minimum and maximum of each parameter in solid tumors, IPF%, IPF#, MPV, PDW and P-LCR significantly increased (p<0.001) before reaching PR. The time between crossing each parameter’s cut-off and PR averaged 6.8±1.5 days (range: 0 to 15) for IPF%, 2.1±0.9 days (-3 to+6) for IPF# and 8.0±1.5 days (0 to 18) for MPV. PDW reached its cut-off 6.6±2.9 days (0 to 15) and P-LCR 8.5±1.2 days (6 to 12) before reaching PR. In leukemia and lymphoma patients, the rise between the minimum and maximum of each parameter was significant (p<0.001) for IPF%, MPV, PDW and P-LCR. Time between reaching the cut-off and PR was 7.3±3.1 days (0 to 30) for IPF%, 4.1±2.6 days (-3 to+24) for IPF# and 10.6±3.1 days (-3 to+36) for MPV. PDW reached the cut-off 9.0±3.6 days (0 to 21), P-LCR 10.4±3.5 days (3 to 24) before PR.

Conclusion: The measurement of these platelet parameters cannot reliably predict the exact time of PR in pediatric oncology patients undergoing chemotherapy. Hence, the importance of these parameters for the indication of PT is markedly limited.

Publication History

Article published online:
13 February 2025