The First Case of E-Cigarette-Induced Polycythemia.

A 71-year-old male smoker was referred to our hospital because of increased hemoglobin and hematocrit. At initial consultation, his hemoglobin and hematocrit levels were 21.8 g/dl and 64.8%, respectively. Other laboratory data and his cardiopulmonary functions were almost normal, and JAK2 V617F mutation was negative. He had smoked about 25 cigarettes per day for 50 years until the age of 70, when he switched from conventional smoking to electronic cigarettes (e-cigarettes). We requested that he quit e-cigarette use. Thereafter, his hemoglobin and hematocrit gradually decreased and normalized. Here, we report the first case of e-cigarette-induced polycythemia.