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Hematocrit

Published: July 27, 2026Updated: August 25, 2026

Hematocrit measures the proportion of red blood cells in the total blood volume, providing insight into the oxygen-carrying capacity of the blood and indicating conditions like anemia or dehydration.

Quick summary

Hematocrit reflects the percentage of red blood cells in blood, aiding in diagnosing anemia and dehydration.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
%
Clinical utility
diagnostic
Result kind
semi_quantitative
FDA-cleared
Sysmex Hematocrit, Abbott Hematocrit, Siemens Hematocrit
interpretation: {"text":"May indicate anemia, blood loss, nutritional deficiencies, or chronic disease.","label":"Low Hematocrit"}; {"text":"May suggest dehydration, polycythemia, or chronic lung disease.","label":"High Hematocrit"}

Hematocrit is a critical component of a complete blood count (CBC) test, which assesses the proportion of red blood cells (RBCs) in the blood. This measurement is essential for evaluating the oxygen-carrying capacity of the blood.

A low hematocrit can indicate anemia, nutritional deficiencies, or chronic diseases, while a high hematocrit may suggest dehydration, polycythemia, or chronic lung disease.

Normal hematocrit levels typically range from 36% to 50% in adults, but these values can vary based on age, sex, and other physiological factors.

Frequently asked questions

What is a normal hematocrit range?
The normal hematocrit range for adults is typically 36% to 50%, but this can vary based on age, sex, and other factors.
What causes low hematocrit?
Low hematocrit can be caused by anemia, blood loss, nutritional deficiencies, or chronic diseases like kidney disease.
  1. 1
    Mayo Clinic: Hematocrit TestSource
  2. 2
    MedlinePlus: HematocritSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy