Retrospective evaluation of clinical and laboratory parameters in patients undergoing phlebotomy at a hematology outpatient clinic

SUMMARY Retrospective Evaluation of Clinical and Laboratory Parameters in Patients Undergoing Phlebotomy at a Hematology Outpatient Clinic Aim: The primary aim of this study is to identify which clinical signs and basic laboratory parameters should raise suspicion for primary polycythemia in healthcare settings where advanced diagnostic tools such as the JAK2 mutation test are not available. This will allow for the timely referral of cases to specialized centers and provide a practical approach for clinical decision-making. Materials and Methods: The study was initiated with approval from the Pamukkale University Non-Interventional Clinical Research Ethics Committee, dated April 22, 2025, with protocol number 08. This retrospective descriptive study evaluated 1,067 patients aged 18 years and older, diagnosed with either primary or secondary polycythemia, who underwent phlebotomy at the Pamukkale University Faculty of Medicine Hematology Outpatient Clinic since 2022. Data were retrieved from the hospital information system and included demographic characteristics, clinical data, laboratory findings, and imaging results. Results: A total of 1,067 patients were included. Among them, 8% (n=89) were female and 92% (n=978) were male, with a mean age of 47.23 ± 15.35 years (range: 18–87). At admission, 25.2% (n=269) of patients presented with symptoms, the most common being headache and dizziness, reported in 152 cases (56.5%). At least one comorbidity was identified in 62.4% (n=666) of patients. The most frequent comorbidities were hypertension (36.8%, n=245), diabetes mellitus (32%, n=213), and pulmonary diseases (28.7%, n=191). A history of thrombosis was noted in 18.5% (n=197) of patients. Additionally, 20.1% (n=214) of participants were diagnosed with obesity, and smoking prevalence was high, with 63.2% (n=674) being active smokers. Abdominal ultrasonography (USG) was performed in 72.7% (n=776) of patients, revealing hepatomegaly in 18.3% (n=142), splenomegaly in 12% (n=93), and polycystic kidney disease in 0.3% (n=2). JAK2 mutation was positive in 9.2% (n=73), while all 465 patients tested for BCR-ABL were negative. Bone marrow biopsy findings showed normocellularity in 37.9% (n=50), hypocellularity in 33.3% (n=44), and hypercellularity in 28.8% (n=38). Statistically significant differences were observed between primary and secondary polycythemia groups in terms of gender (p=0.001), obesity (p=0.007), smoking (p=0.001), age at diagnosis (p=0.001), hypertension (p=0.001), splenomegaly (p=0.001), JAK2 positivity (p=0.001), bone marrow biopsy findings (p=0.001), hematocrit (Hct, p=0.001), white blood cell count (WBC, p=0.001), mean corpuscular volume (MCV, p=0.001), mean platelet volume (MPV, p=0.015), lactate dehydrogenase (LDH, p=0.001), lymphocyte (p=0.001), neutrophil (p=0.001), eosinophil (p=0.001), basophil (p=0.001), platelet count (p=0.001), ferritin (p=0.001), vitamin B12 (p=0.001), creatinine (p=0.001), erythropoietin (EPO, p=0.001), and phlebotomy frequency at both 6 months (p=0.001) and 12 months (p=0.001). Among JAK2-positive patients, both 6-month (p=0.002) and 12-month (p=0.007) phlebotomy frequencies were significantly higher compared to JAK2-negative patients. Conclusion: Our study provides a comprehensive comparison of clinical, laboratory, and genetic characteristics in patients with primary and secondary polycythemia who underwent phlebotomy. Notably, JAK2 mutation positivity, bone marrow cellularity, erythropoietin levels, and hematologic parameters emerged as key indicators for differential diagnosis. Lifestyle-related factors such as obesity and smoking were more prevalent in secondary polycythemia, emphasizing the need for etiologic investigation. These findings underscore the necessity for an individualized, multifactorial approach in diagnosis and management, and highlight the importance of validating our results through large-scale, prospective studies. Keywords: Polycythemia, JAK2 mutation, Phlebotomy