Case Study: Large Platelets in a Trauma Patient

Deanne Chapman
Vanderbilt University Medical Center
Nashville, Tennesee, USA

Clinical Data

This trauma patient was a 72 year-old male with aortic and mitral valve prostheses under chronic anticoagulation therapy with warfarin. He was admitted to the Trauma Unit with a ruptured spleen and acute blood loss. Splenectomy and blood transfusions were required.

Laboratory Data

Laboratory results showed a WBC of 12.25 x 10³/µL, Hgb of 8.9 g/dL, HCT of 26.3%, PLT count of 432 x 10³/µL, MCV of 78.5 fL, RDW of 16.5%, and MPV of 13.2 fL.

Morphology

No abnormal white cells were reported on peripheral blood smear. RBC morphology revealed 2+ anisocytosis, 1+ poikilocytosis, 1+ microcytosis, 1+ spiculated, 1+ schistocytes, 1+ polychromasia, and 2+ hypochromia. Platelet sufficiency was increased with numerous large platelets present (Figure 1).

Table 1. Laboratory Data: CBC and Automated Differential

ADVIA 120 Pattern Significance

ADVIA 120 results showed an increased presence of Large Platelets (50 x 10³/µL) seen clearly on platelet cytograms (Figure 2). The mean platelet volume (MPV) was 13.2 fL, suggestive of presence of Large Platelets. The ADVIA 120 analysis range for platelets is 1-60 fL, thus platelets with volumes up to 60 fL are counted. The Large Platelets flag alerts the user of their presence.

Discussion

The patient's platelet count was 432 x 10³/µL, but has been as high as 1,013 x 10³/µL in the past. Thrombocytosis (platelet count above 450 x 10³/µL) can result from several conditions (1,2):

1. Physiologic - exercise, epinephrine, childbirth

2. Primary (platelet count usually >1,000 x 10³/µL) - Myeloproliferative syndromes (e.g., essential thrombocythemia, polycythemia vera, chronic myelocytic leukemia, myelofibrosis, idiopathic refractory sideroblastic anemia). This group of disorders is more likely to produce platelets with abnormal size and shape, which have been reported on our patient's peripheral blood smear.

3. Secondary (platelet count usually <1000 x 10³/µL) - infectious diseases, chronic inflammatory diseases, neoplasms, acute hemorrhage, hemolytic anemias, recovery from thrombocytopenia, post splenectomy, iron deficiency, surgery.

A single underlying cause of our patient's thrombocytosis with abnormal platelets is not clear, since he has multiple contributing factors.

References

1. Levine, Shirley Parker: Thrombocytosis. Chapter 66 in: Wintrobe's CLINICAL HEMATOLOGY, 10th Edition. Edited by Lee, G. Richard, Ferster, John, Lukens, John, Paraskeuas, Frixus, Greer, John P., Rogers, George M. Baltimore, Williams & Wilkins, 1999.

2. Davis, Gerald L.: Quantitative and Qualititative Disorders of Platelets. Chapter 57 in: Clinical Hematology Principles, Procedures, Correlation. 2nd Edition. Edited by Stiene-Martin, E. Anne, Lotspeich-Steininger, Cheryl A., Koepke, John A. Philadelphia, Lippincott, 1998.

Figure 1. Blood smear

Figure 2. ADVIA 120 cytograms

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