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Normal HCT Levels

Updated February 21, 2017

HCT is an abbreviation of "hematocrit." It is a routine blood test that is used as a marker of general health. Most commonly, it is checked prior to surgery and often with hospital admissions.

Definition

HCT is the proportion of blood that is expressed as a percentage of the red blood cells (erythrocytes) to the rest of the blood constituents.

Measurment

A blood sample is obtained and sent to the lab to be measured. The HCT is calculated based on the total volume of red blood cells and the amount of haemoglobin (the red part of the blood).

Normal HCT Levels in Adults

Normal HCT levels in women are 38 to 46 per cent. Women naturally have a lower HCT level than men. Normal HCT levels in men are 42 to 54 per cent.

Normal HCT Levels in Children

HCT levels in children vary with age. A newborn level should be 55 to 68 per cent. By one month, normal levels are 37 to 49 per cent. At the end of one year, 29 to 41 per cent, and at 10 years, 36 to 40 per cent. After puberty, the ranges are dependent on the patient's gender.

Causes of low HCT levels

Anemia is the medical term for a low HCT levels. It is most often caused by a loss of blood. Another common cause is iron deficiency in the diet. Sickle cell anaemia and certain types of kidney problems will often cause HCT levels to be low, as well.

Causes

High HCT levels can be caused by dehydration, and people living at high altitudes often exhibit raised HCT levels. A side effect of chronic smoking is increased HCT levels.

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About the Author

Cheryl Balasubramanyam is a freelance writer working out of her home on the East Coast. She holds degrees in psychology and science and has written for medical and information technology journals. Her areas of expertise include patient education on heart disease and diabetes, as well as maternity issues.