Significant Variability in the Initial Workup of Thrombocytopenia in the Hematology Clinic - What Is the "Optimal" Workup?
Authors: Ravindran Aishwarya , Go Ronald S. , Reichard Kaaren K. , Marshall Ariela L. 
Published: November 2019

Abstract
BACKGROUND: Thrombocytopenia is a common hematologic condition associated with multiple etiologies ranging from benign to malignant to potentially life-threatening disorders. Given the heterogeneity of clinical presentations, available clinical information, and pertinent clinical history, there are inter-physician variations in the approach to the workup of thrombocytopenia in the hematology clinic. While a limited test repertoire may be adequate for many cases, more extensive testing may be warranted in others. We were interested in analyzing the various tests performed and testing approaches in the initial workup of thrombocytopenia.
METHODS: We reviewed the records of 69 patients who were referred to our center between 2010 and 2015 for an initial workup of thrombocytopenia. We collected epidemiologic data, laboratory testing results, and pathologic findings. Pathologic results were classified as "normal" or "abnormal" and further subcategorized on the basis of review by two clinicians. Quantitative data were analyzed using JMP Pro 10.0.2 software.
RESULTS: At the time of thrombocytopenia diagnosis, the median age was 59 years (range: 17-90) and majority were males (65%). The median platelet count was 91,000/µL (range: 3,000-146,000). Isolated thrombocytopenia was present in 51 cases (74%). Forty-four patients (64%) had a peripheral blood smear review and 4 (9%) contained abnormalities including hypogranular neutrophils, rouleaux formation, and target cells. Autoimmune workup included anti-platelet antibody (APA) in 34 (49%), anti-nuclear antibody (ANA) in 21 (30%), lupus anticoagulant (LA) in 4 (6%) and rheumatoid factor (RF) in 13 (19%) of cases. Autoimmune testing was positive for APA in 2 (5.9%), ANA in 4 (19%), LA in 0 (0%), and RF in 1 (8%) of patients who underwent testing, respectively. Common infectious workups included human immunodeficiency virus in 23 (33%), hepatitis A virus in 2 (3%), hepatitis B virus in 11 (16%), hepatitis C virus in 22 (32%), Epstein-Barr virus in 5 (EBV, 7%), cytomegalovirus in 7 (10%) and Helicobacter pylori in 5 (7%) of patients, and were negative in all cases except for one patient with evidence of active EBV infection. Sixteen patients (23%) underwent bone marrow biopsy, and 2 (12.5%) were diagnosed with hematologic malignancies including myelodysplastic syndrome and hairy cell leukemia. Based on results of these tests, 28 (41%) patients were diagnosed with primary immune thrombocytopenia, 19 (27%) with thrombocytopenia secondary to another medical condition, and 22 (32%) with thrombocytopenia of undefined etiology.
CONCLUSION: Thrombocytopenia is a common laboratory finding, and workup involves significant inter-clinician variation, often involving multiple laboratory tests and in some cases invasive tests such as bone marrow biopsy. We found that autoimmune causes of thrombocytopenia were moderately common and infectious and malignant causes were rare. Our findings were based on a small cohort of patients but are likely to be representative of the clinical practice in a large tertiary care center. Large scale studies may be warranted to devise a protocol for a thorough yet cost-effective and stepwise initial workup of thrombocytopenia and to minimize unwarranted inter-clinician variation in such investigations.

Disclosures
No relevant conflicts of interest to declare.