Department of Internal Medicine, Richmond University Medical Center, Staten Island, NY, USA.
A 38-year-old Hispanic woman with a past medical history of pulmonary embolism, DVT, and asthma was seen for an evaluation of her recurrent episodes of thrombosis. She had experienced three episodes of DVT and one episode of pulmonary embolism. The first episode of DVT occurred 5 years ago, and the second episode happened 3 years ago. The pulmonary embolism occurred 1 year ago, following her third episode of DVT. Each DVT episode presented with lower leg edema and pain, and was confirmed by lower extremity ultrasound. The pulmonary embolism episodes presented as shortness of breath and low oxygen saturation.
She was given the following medications to take at home: Ipratropium-Albuterol (Duoneb Neb), 3 mL by inhalation every 4 hours as needed, and warfarin sodium (Coumadin), 12 mg orally once daily. However, she was non-adherent to the use of warfarin. The notable aspects of her family history were that her mother had diabetes mellitus and hypertension, while her father had colon cancer at age of 42. She was a current smoker and had been smoking 2 packs of cigarettes daily for 20 years. She denied alcohol and drug use. A review of systems was non-contributory.
A recent complete blood cell count revealed the following: white blood count 11.1×109/L, hemoglobin level 14.9 g/dL, hematocrit 45.4%, mean corpuscular volume (MCV) 81.6 fL, mean corpuscular hemoglobin (MCH) level 30.7 pg, mean corpuscular hemoglobin concentration (MCHC) 32.8 g/dL, platelet count 555×109/L, neutrophil 46%, lymphocyte 41%, monocyte 4.6%, eosinophil 3.9%, and basophil 0.1%. A basic metabolic profile (BMP) showed the following levels: sodium 139 mmol/L, potassium 4.1 mmol/L, chloride 109 mmol/L, carbon dioxide 29 mmol/L, blood urea nitrogen (BUN) 6 mg/dL, creatinine 0.6 mg/dL, glucose 86 mg/dL, calcium 9.1 mg/dL, phosphorus 3.8 mg/dL, magnesium 2.2 mg/dL, total protein 7.8 g/dL, albumin 3.7 g/dL, aspartate amino-transferase (AST) 16 U/L, alanine amino-transferase (AST) 20 U/L, and alkaline phosphatase 119 U/L.
Her latest chest computed tomography showed a small incomplete filling defect in the right upper lobe, suggesting a chronic non-occluding pulmonary embolism. A coagulation workup, including lupus anticoagulant, protein C and S level/activity, antithrombin III level/activity, factor V level/activity, anti-cardiolipin IgG antibody, anti-cardiolipin IgM antibody, beta 2-GPI antibody (IgG,IgA, and IgM), Von Willebrand factor (VWF), factor VIII, methylenetetrahydrofolate reductase (
The patient's platelet count has been in the higher range, from 350×109/L to 800×109/L, during the last 5 years. Some articles have mentioned that, in order to diagnose ET, it is necessary to have two platelet counts above 600×109/L that were measured 1 month apart. On the other hand, the recent World Health Organization definition reduces this threshold to 400×109/L, if that value is sustained. However, the laboratory findings for our patient did not satisfy either of the definitions of ET. The co-occurrence of the high platelet level and recurrent thrombosis, in the absence of other procoagulant abnormalities, highlights the possibility of a myeloproliferative disorder.
There is a proven correlation between PV and ET, and
ET is mainly caused by mutations in exon 9 of
To date, the phenotypic features of the individual mutations of