Unmasking and aggravation of polycythemia vera by canagliflozin.

Sodium-glucose co-transporter-2 inhibitors are novel antidiabetes drugs that act via inhibition of renal glucose reabsorption. This action causes osmotic diuresis, reduces intravascular volume and is associated with various adverse effects. In the present paper, we describe the first report on the unmasking of underlying polycythemia vera by canagliflozin in a person with Type 2 diabetes mellitus, which was temporally related to the use of the drug.

A 51-year-old obese man with Type 2 diabetes was prescribed canagliflozin 100 mg for control of his glycaemia. He presented 6 months later with asymptomatic elevation of his haemogram measurements (haemoglobin: 16.9 g/dl; haematocrit: 55%; red cell number: 8.1 million/mm3 ; total leukocytes: 23010/mm3 ; platelet count: 9.7 *106 /mm3 ). He had no history of smoking, exposure to high altitude or other drugs. Subsequent investigations revealed myeloproliferative neoplasm (polycythemia vera) on trephine biopsy of bone marrow, normal erythropoietin level and JAK2V617F positivity. Because of the possibility that the underlying condition had been unmasked by canagliflozin, the latter was stopped. This led to a remarkable improvement in the man's haematological profile, with no other significant intervention. The man subsequently restarted the drug of his own accord, causing his haematological profile to worsen again and thereby posing a challenge in monitoring of both polycythemia vera as well as diabetes mellitus.

This report brings to light unmasking of a new adverse effect of sodium-glucose co-transporter-2 inhibitors in clinical practice caused by volume loss, apart from hypotension and falls.