High haemoglobin / haematocrit

South Tees Hospitals NHS Foundation Trust

Definition/Description

Investigation is suggested if the haematocrit is persistently (>2 months, preferably repeated without tourniquet) >0.52 (male) or >0.48 (female). This may be due to increased red cell mass (true polycythaemia) or reduced plasma volume (apparent polycythaemia). If the haematocrit is >0.6 (male) or >0.56 (female) then it can be assumed that there is a true increase in red cell mass.

Red Flag Symptoms

None provided

Guidelines on Management

Differential Diagnosis:

Apparent polycythaemia may be due to a variety of causes such as diuretics, heavy smoking or alcohol, dehydration, stress, oedema, hypertension or obesity.
True polycythaemia
- Reactive to hypoxia - e.g. pulmonary disease, carbon monoxide / heavy smoking, sleep apnoea or congenital cyanotic heart disease.
- Abnormal high erythropoietin - e.g. secondary to various tumours (e.g. renal carcinoma or hepatoma), renal transplant or renal artery stenosis.
- Polycythaemia vera - bone marrow disorder with uncontrolled red cell proliferation. Usually positive for JAK2 V617F mutation. Associated with thrombotic and haemorrhagic complications. May be associated with generalised itch (classically after a hot shower or bath), splenomegaly or raised WCC / PLT.
- Endocrine - Cushing's syndrome, Conn's syndrome, phaecochromocytoma or androgens (including testosterone supplements and anabolic steroids).
- Inherited erythropoietin or haemoglobin variants (rare).

Examination:

Features of cardiac or pulmonary disease.
Features of hyperviscosity (fatigue, headache, slowed thought, muscosal / retinal bleeding, blurred / double vision, chest / abdominal pain, myalgia).
Splenomegaly suggests polycythaemia vera, although this is not consistent.

Baseline investigations:

FBC, U+E, LFT, ferritin (a high haematocrit despite low ferritin strongly suggests polycythaemia vera. DO NOT give iron replacement).
Review cardiovascular risk factors, although primary aspirin prophylaxis is not recommended unless PRV.
Further tests as indicated by history, e.g. oxygen saturations, PFT, CXR.

Referral Criteria/Information

Referral:

Review cardiovascular risk factors for all patients, regardless of cause.
Haematocrit persistently >0.52 (male) or >0.48 (female) without obvious cause or with suspicion of polycythaemia vera. URGENT referral if features of hyperviscosity.
Other referrals as directed by suspected cause, e.g. may benefit from long-term oxygen therapy or ACE-inhibitors if chronic hypoxia.