High Red Blood Cell Count (Polycythemia): Symptoms, Causes and Tests

What it involves

The MedlinePlus encyclopedia describes polycythemia vera as a bone marrow disease that leads to an abnormal increase in the number of blood cells, mostly red blood cells. It is rare, and it must be told apart from other causes of increased red blood cells, which is the first job of an evaluation.

Who this is for

• Adults whose blood work showed a high red blood cell count, hemoglobin or hematocrit.
• Patients with headaches, dizziness, itching after a warm bath or a red, flushed face.
• People with lung disease or low oxygen levels who have been told their red cell count is high.
• Anyone who has had a blood clot and is now told their blood counts are abnormal.

What to expect

• Questions about symptoms, smoking, sleep, medicines, lung conditions and clotting history
• A check of blood pressure, oxygen level, skin color and the upper left belly
• Blood work, which the practice offers, such as a complete blood count and a metabolic panel
• A referral to a blood specialist for genetic testing or a bone marrow test when it is needed

Why thick blood causes symptoms

According to the MedlinePlus encyclopedia, too many red blood cells make the blood thicker, so it cannot flow through small blood vessels normally. That can lead to headache, dizziness, tiredness, shortness of breath, vision trouble and a ringing in the ears. Thicker blood can also form clots in veins near the skin surface. Many people feel nothing at all, and the encyclopedia says the condition is often found before severe symptoms occur. The fatigue guide and the headache guide cover common causes of those two complaints.

Polycythemia vera and other causes

MedlinePlus says polycythemia vera mostly causes too many red blood cells, with white cells and platelets sometimes higher too. It is rare, occurs more often in men, is not usually seen under age 40 and is often linked to a gene variant called JAK2. The encyclopedia stresses that it must be distinguished from other causes of increased red blood cells. In its page on pulmonary fibrosis it notes that low blood oxygen can raise red cell levels, and the sleep apnea guide and the COPD guide describe two common reasons for low oxygen.

Tests a provider may use

The encyclopedia lists a complete blood count with differential, a comprehensive metabolic panel, an erythropoietin level, a vitamin B12 level, a genetic test for the JAK2 variant, an oxygen saturation reading and a bone marrow biopsy. The practice offers blood work, and the complete blood count guide explains the first test. Genetic testing and a bone marrow biopsy are arranged by referral to a blood specialist.

How it is treated

The encyclopedia says the goal is to reduce the thickness of the blood and prevent bleeding and clotting problems. It lists phlebotomy, which removes about a pint of blood each week until the red cell count drops, and medicines such as hydroxyurea, interferons and ruxolitinib. It also says aspirin may be an option for some people to reduce clotting risk, though it raises the chance of stomach bleeding, and light therapy can ease severe itching. These are decisions for a blood specialist, not something to start on your own.

What can go wrong if it is missed

MedlinePlus lists possible complications including blood clots that can cause a stroke or heart attack, bleeding from the stomach or other parts of the digestive tract, gout, heart failure, and changes in the bone marrow that can lead to scarring or leukemia. That list is the reason a high count is followed rather than ignored. The stroke warning signs guide and the leg blood clot guide describe signs that need an emergency response.

When to be seen and when to go to the ER

Make an appointment for a high count on blood work, or for headache, flushing, itching and dizziness that keep returning. Call 911 or go to the ER for sudden weakness on one side, trouble speaking, vision loss, chest pain, severe shortness of breath, or a swollen, painful leg, which can mean a stroke, heart attack or blood clot. A full feeling in the upper left belly can reflect an enlarged spleen, and a blood in stool guide covers one bleeding sign to report right away.

Sources

• MedlinePlus Medical Encyclopedia: Polycythemia vera
• MedlinePlus Medical Encyclopedia: Idiopathic pulmonary fibrosis