Hematocrit is a measure of the percentage of red blood cells (RBCs) in a person’s blood. It is an important parameter to determine the health of an individual’s blood and the oxygen-carrying capacity of the blood.

A hematocrit test measures the volume of RBCs in a sample of blood as a percentage of the total blood volume. The normal range for hematocrit varies between 38% and 52% for men, and 35% to 47% for women. There are several factors that can affect hematocrit levels, which we will discuss below.

1. Gender

One of the main factors that affect hematocrit levels is gender. The normal range for hematocrit is lower in women compared to men.

This is because the average size of RBCs in women is smaller than that in men, and women tend to have a higher percentage of plasma volume compared to men. The hormonal changes that occur during pregnancy can also affect a woman’s hematocrit levels.

2. Age

Age is another factor that can influence hematocrit levels.

The hematocrit level tends to decrease with age due to several factors, including changes in the bone marrow that produce RBCs, a decrease in the size and number of RBCs, and an increase in the percentage of plasma volume. Older individuals also tend to have a higher incidence of chronic diseases, which can affect the hematocrit levels.

3. Altitude

Altitude is an important environmental factor that can influence hematocrit levels. At higher altitudes, there is less oxygen in the air, which can lead to hypoxia.

To compensate for this, the body produces more RBCs to ensure adequate oxygen delivery to the tissues. This increase in RBC production can lead to higher hematocrit levels in individuals living at high altitudes.

4. Dehydration

Dehydration is a common cause of elevated hematocrit levels. When a person becomes dehydrated, the amount of plasma volume in the blood decreases, causing the concentration of RBCs to increase. This can lead to a falsely elevated hematocrit reading.

It is important to ensure adequate hydration before getting a hematocrit test to avoid misleading results.

5. Chronic Diseases

Chronic diseases such as kidney disease, liver disease, and cancer can affect hematocrit levels. In these conditions, there is a disruption in the balance between RBC production and destruction, leading to changes in hematocrit levels.

For example, kidney disease can cause a decrease in erythropoietin, a hormone that stimulates RBC production, leading to low hematocrit levels.

6. Medications

Certain medications can also affect hematocrit levels.

Blood-thinning medications like warfarin and aspirin can reduce the number of RBCs in the blood, while androgens, such as testosterone, can increase RBC production and lead to high hematocrit levels. Chemotherapy drugs can also affect the production of RBCs, leading to low hematocrit levels.

In conclusion, hematocrit levels are affected by several factors, including gender, age, altitude, dehydration, chronic diseases, and medications. It is important to identify and understand these factors to interpret hematocrit test results accurately.