At age 69, Stefano does not enjoy good health. Having migrated to Australia from Europe some decades ago, he has had to contend with around a decade of metabolic syndrome, peripheral vascular disease and multiple angioplasties, and colon cancer in 2017. He was a heavy smoker until a low-grade lung cancer was resected in 2020. His HbA1c hovers around 6.4%. His medications are low-dose aspirin, perindopril, atorvastatin and metformin. 

Stefano presents to his usual GP for review of recent blood test results. The GP notes he appears more plethoric than usual, and has new marked palmar erythema. His weight is 106kg, BMI 31kg/m². 

His haemoglobin is 192g/L (normal 130-150) and haematocrit is 62% (normal 40-54), while ferritin is low at 19μg/L (normal 30-620). His FBC was normal 18 months previously.  

Noting the features of polycythaemia, the GP organises further testing, including serum erythropoietin (EPO), JAK2 mutation, and a sleep study. On further questioning, Stefano has no symptoms of polycythaemia.