Overview

Hematocrit levels refer to the percentage of red blood cells (RBCs) in the total volume of blood. This measurement is a crucial part of a complete blood count (CBC) test and helps evaluate a person's overall health and ability to transport oxygen throughout the body. Normal hematocrit levels vary by age, sex, and altitude of residence. For adult males, typical levels range from 40% to 54%, for adult females 36% to 48%, and for children around 35% to 45%. Abnormal hematocrit levels—either too high or too low—can indicate various health conditions, including anemia, dehydration, or bone marrow disorders.

Causes

Abnormal hematocrit levels can be classified into two categories: low hematocrit (anemia) and high hematocrit (polycythemia). The underlying causes differ based on whether levels are elevated or reduced.

Causes of Low Hematocrit:

• Iron Deficiency Anemia: The most common cause, often due to inadequate dietary intake or blood loss.
• Vitamin Deficiencies: Lack of vitamin B12 or folate can impair red blood cell production.
• Chronic Diseases: Conditions such as kidney disease, cancer, or chronic infections can reduce hematocrit levels.
• Bone Marrow Disorders: Diseases like leukemia or aplastic anemia affect blood cell production.
• Blood Loss: Heavy menstruation, gastrointestinal bleeding, or surgery can lead to lower hematocrit.

Causes of High Hematocrit:

• Dehydration: A reduced plasma volume artificially raises hematocrit levels.
• Polycythemia Vera: A bone marrow disorder causing excessive red blood cell production.
• Living at High Altitudes: Increased RBC production as a natural response to lower oxygen levels.
• Lung Diseases: Conditions like COPD trigger increased RBC production to compensate for poor oxygen exchange.
• Smoking: Chronic smoking can elevate hematocrit levels.
• Performance-Enhancing Drugs: Use of erythropoietin (EPO) or anabolic steroids may increase hematocrit.

Symptoms

Symptoms of abnormal hematocrit levels vary depending on whether the levels are too low or too high and how severe the imbalance is.

Symptoms of Low Hematocrit:

• Fatigue and Weakness: Due to reduced oxygen-carrying capacity.
• Pale Skin: Paleness may be noticeable in the face, palms, or gums.
• Shortness of Breath: Especially during physical activity.
• Headaches and Dizziness: Common in people with significant anemia.
• Cold Hands and Feet: Poor circulation may cause extremities to feel cold.

Symptoms of High Hematocrit:

• Headaches: Due to increased blood viscosity.
• Blurred Vision: Can result from thicker blood flow affecting small vessels.
• Ruddy Complexion: A flushed, red appearance, particularly on the face.
• High Blood Pressure: Increased blood volume can elevate blood pressure.
• Itching: Especially after bathing, common in polycythemia vera.
• Increased Risk of Blood Clots: High hematocrit increases clotting risk, potentially leading to strokes or heart attacks.

Diagnosis

Hematocrit levels are routinely measured using a simple blood test:

• Complete Blood Count (CBC): The hematocrit test is part of the CBC panel, which measures the proportion of red blood cells to total blood volume.
• Blood Smear: A microscopic examination of blood cells can help identify shape and size abnormalities.
• Reticulocyte Count: Measures immature red blood cells to assess bone marrow activity.
• Ferritin, Vitamin B12, and Folate Tests: Help identify nutritional deficiencies causing anemia.
• Erythropoietin Levels: Can indicate if the body is producing appropriate signals for RBC production.
• Bone Marrow Biopsy: Performed if bone marrow diseases are suspected.
• Additional Tests: Depending on initial results, doctors may order kidney function tests, oxygen saturation, or genetic testing.

Treatment

Treatment of abnormal hematocrit levels depends on whether they are too low or too high and on the underlying cause.

Treatment for Low Hematocrit:

• Iron Supplements: Common for iron-deficiency anemia.
• Vitamin Supplementation: B12 or folic acid supplements in cases of nutritional deficiencies.
• Dietary Changes: Encouraging iron-rich foods like red meat, leafy greens, and legumes.
• Treating Underlying Conditions: Managing chronic diseases such as kidney disease or infections.
• Blood Transfusions: In severe cases of anemia.

Treatment for High Hematocrit:

• Phlebotomy: Therapeutic removal of blood, especially in polycythemia vera.
• Hydration: Treating dehydration can normalize levels.
• Medications: Drugs like hydroxyurea in polycythemia vera to reduce RBC production.
• Lifestyle Changes: Quitting smoking and treating sleep apnea.
• Treating Lung or Heart Disease: Managing the underlying condition can help regulate hematocrit.

Prognosis

The prognosis for individuals with abnormal hematocrit levels largely depends on the underlying cause and how quickly it is addressed.

• Low Hematocrit: In most cases, especially with nutritional anemia, treatment leads to full recovery. Chronic illnesses may require ongoing management.
• High Hematocrit: Prognosis is good if managed early, but untreated high hematocrit, especially due to polycythemia vera, increases risks of serious complications like thrombosis.
• Monitoring: Regular follow-up and blood tests are essential to monitor hematocrit levels and adjust treatment plans accordingly.
• Long-Term Health: With proper care and attention to the underlying causes, many people with abnormal hematocrit levels can lead healthy, active lives.

Timely diagnosis and personalized treatment are key to managing hematocrit-related health concerns effectively.