A 62-year-old obese male with a known medical history of hypertension presented with generalized headaches and lethargy. He was taking bendroflumethiazide, 2.5 mg once daily for hypertension. The only other past medical history included a left-sided deep vein thrombosis six months previously. There was no history of alcohol abuse or smoking.
On examination he was obese. His chest was clear and examination of the abdomen did not reveal any abnormality. Investigations are shown.
Hb 20 g/dl MCV 88 fl WCC 15 109/l Platelets 500 109/l PCV 0.66 l/l Sodium 141 mmol/l Potassium 4.2 mmol/l Urea 8 mmol/l Creatinine 110 mol/l Urate 0.44 mmol/l
What is the cause of his symptoms?
a. Obstructive sleep apnoea.
b. Gaissbock’s syndrome.
c. Polycythaemia rubra vera.
d. Renal cell carcinoma.
e. Chronic hypoxaemia
Answer:
The high Hb is suggestive of polycythaemia. There is nothing in the history to indicate a secondary cause, e.g. hypoxia, renal carcinoma, adrenal tumour. Although he was obese, there was nothing else in the history to allow the diagnosis of obstructive sleep apnoea. The high white cell count and platelet count favour primary polycythaemia (polycythaemia rubra vera). Headache and lethargy are common symptoms of polycythaemia rubra vera. Polycythaemia rubra vera causes lethargy due to hyperviscosity and raised interleukin-6 levels. Other classic features include visual disturbance, abdominal pain and pruritus.
Many patients with polycythaemia rubra vera have splenomegaly; however, a palpable spleen is absent in approximately one third of patients. Criteria for the diagnosis of polycythaemia rubra vera Raised red cell mass and normal pO2 with either splenomegaly or two of the following: • WCC >12 109/l • Platelets >400 109/l • Raised B12 binding protein • Low neutrophil alkaline phosphatase concentration