The number of red blood cells in the blood is important because these cells carry hemoglobin, the molecule that binds to oxygen, which is carried to the different parts of the body. Hematocrit (Hct) is a test that determines the amount of red blood cells in a given volume of blood, which is expressed in percentage. People who have a low Hct have a low percentage of RBCs in their blood, and there are many causes why this may happen.

Causes of Low Hct

The normal hematocrit range is 38.5 – 50% in men and 34.9 – 44.5% in women. Children up to 15 years old have varying ranges, depending on their age and sex. Low Hct is usually associated with anemia, and causes include:

1. Anemia

A person who does not have enough RBCs to carry oxygen to the tissues is said to be anemic, which can make one feel tired all the time. Common symptoms of anemia include paleness, fatigue, cold hands/feet, irregularities in heartbeats, and poor mental function. There are different types of anemia according to cause, some of which may be due to serious illness. Consult a doctor if you think you may have anemia to be able to get proper treatment. Anemia can be prevented by eating a balanced diet, if the cause is due to iron deficiency. However, some forms of anemia may need other medical procedures such as blood transfusion.

2. Leukemia

Cancer of the blood and other blood-forming tissues such as the bone marrow and lymphatic system is called leukemia. Although this condition has different types, common symptoms are persistent tiredness, fever, chills, weakness, and weight loss. Leukemic patients also suffer from frequent infections, bone pain and easy bleeding. They can have swollen lymph nodes and red spots called petechiae. Treatment is based on the type of condition and complications. These usually include chemotherapy, biological therapy, radiation therapy, and stem cell transplantation.

3. Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) or lupus for short, is an autoimmune disease that affects the blood and causes anemia in 50% of children affected. It manifests as low Hct, low platelet and low white blood cell (WBC) counts. These may be also be due to side effects of treatment. SLE patients may experience fatigue due to various factors such as anemia, pain, depression, poor physical fitness, and poor sleep.

4. Rheumatoid Arthritis

People with rheumatoid arthritis do not only experience joint pains, they also suffer from anemia. This autoimmune disease is characterized by chronic inflammation, which also affects iron metabolism, function of the bone marrow, and production of erythropoeitin (a hormone secreted by the kidney). These lead to low Hct. Treatment includes rest, joint protection, right amount of exercise, medications and patient education. Surgery may be needed occasionally.

5. Medication Effects

Certain medications have side effects that can cause low Hct. Common examples of medications are penicillin and chloramphenicol. Penicillin is used for infections of the throat, tooth, sinuses and others. Chloramphenicol can induce bone marrow depression, which leads to anemia. These medications should not be used without a doctor's advice to avoid these serious complications.

6. Nutritional Deficiency

Nutritional deficiency can cause iron deficiency anemia, which is characterized by low Hct, low hemoglobin and low serum ferritin levels. A lack of iron in the diet is the most common type of nutritional deficiency and a common cause of anemia worldwide. This type of anemia may be associated with growth spurt in children and pregnancy in women. Other conditions that can increase the demand for iron or reduce its amount in the diet include dieting, surgery, or disease. Treatment depends on these conditions and may include intake of nutritional supplements.

7. Overhydration

Low Hct can occur when there is too much fluids in the body or overhydration. When the kidneys cannot eliminate excess water in the body complications such as behavioral and mental changes, seizures and coma may ensue. In mild cases, restriction of fluid intake may correct the problem. However, in severe cases, doctors may prescribe diuretics, which increase fluid excretion or urination.

8. Other Causes

Malnutrition, acute bleeding from trauma, chronic bleeding, red blood cell destruction, and edema (swelling of the body) may also cause low Hct. Treatment depends on the cause, which may include nutritional supplements, pharmacological treatment or surgery.