Hematology – Elevated Hemoglobin: By Karima Khamisa M.D.

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Hematology – Elevated Hemoglobin
Whiteboard Animation Transcript
with Karima Khamisa, MD
https://medskl.com/Module/Index/eleva...


Polycythemia refers to an elevation in measured red cell concentration, reflected by markedly elevated hemoglobin levels (typically above 185 g/L in males, 165 g/L in females) and hematocrit levels.

Polycythemia may be a “relative polycythemia” resulting from dehydration or volume contraction or an “absolute polycythemia” where there is an increase in the number of red cells. Absolute polycythemia may be primary or secondary.

Primary Polycythemia (or polycythemia vera) is caused by a mutation in the kinase that stimulates red blood cell production i.e. the JAK2V617F mutation. Patients can be tested for this mutation, which is positive in 80-95% of patients with polycythemia vera.
Secondary polycythemia is due to conditions such as sleep apnea or hypoxia that stimulate erythropoietin (EPO) to produce red cells. Inappropropriate erythropoietin production is seen in patients with rare tumours. Medications such as synthetic EPO and testosterone can also stimulate red cell production.

Patients with polycythemia vera can be asymptomatic. However they often suffer

Hyperviscosity symptoms (headaches, vertigo, burning at the extremities)or
Thrombotic symptoms such a deep vein thrombosis, pulmonary embolus, hepatic vein thrombosis, myocardial infarction, stroke or digital infarcts/critical limb ischemia.
Patients may also have symptoms of gout, heartburn or pruritus due to excessive histamine release from mast cells. Patients can also have bleeding symptoms.

Once a diagnosis of polycythemia is made, a referral to a hematologist for further management is appropriate. Medications that may be contributing to polycythemia must be stopped. Smoking cessation can often normalize hemoglobin levels, and this must be strongly encouraged in a patients with all forms of polycythemia.

In patients with polycythemia vera, therapeutic phlebotomy is indicated to reduce the hematocrit to 45%: ASA 81 mg a day is started and a cytoreductive agent such as hydroxyurea may be initiated by a hematologist.

The primary care provider has a role in managing cardiac risk factors in patients with polycythemia (hypertension, hyperlipidemia and glycemic control) as the most common cause of death in patients with polycythemia is due to thrombotic complications.