Platform
Company
Complete Blood Count
Review status
Currently under review
Pending specialist review and validation.
Hematocrit measures the proportion of your blood that is made up of red blood cells. It reflects how concentrated your red cells are relative to the liquid part of blood, called plasma. The result is reported as a fraction or as a percent, and it is a core part of the complete blood count.
The test is performed on a blood sample using an automated analyzer that calculates the red cell volume fraction. Hematocrit helps describe oxygen carrying capacity along with hemoglobin and provides context for hydration and circulation status.
Clinicians use hematocrit to evaluate symptoms such as fatigue, shortness of breath, dizziness, or paleness, and to monitor conditions that affect red blood cells. A lower value can point to anemia due to iron deficiency, chronic disease, kidney problems, blood loss, or bone marrow disorders. A higher value may be seen with dehydration, chronic lung or heart disease, smoking, or disorders that increase red cell production.
Hematocrit is also used to monitor response to treatment, to check readiness for surgery, and to assess overall health during pregnancy or chronic illness. Interpreting hematocrit alongside hemoglobin, red blood cell count, and indices like mean cell volume provides a fuller picture of red cell health.
Your result is interpreted in the context of your age, sex, and health status. Values that are lower than expected often suggest anemia or recent blood loss. Your clinician may order iron studies, vitamin tests, a reticulocyte count, or kidney function tests to find the cause. If you are receiving intravenous fluids or have had recent surgery, a repeat test after stabilization may be helpful.
Higher than expected results can reflect reduced plasma volume from dehydration or an increase in red cell mass. Living at high altitude, smoking, or certain hormones can contribute. Your clinician may recommend repeat testing after hydration, a review of medications, oxygen level measurement, or targeted tests to evaluate lung function or red cell production if needed.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Dehydration concentrates red cells and can raise hematocrit, while recent intravenous fluids dilute the blood and can lower it. Let your care team know about recent illness, vomiting, or IV fluids.
Standing, prolonged tourniquet use, or fist clenching during the draw can concentrate blood and slightly increase hematocrit. Relax your arm and avoid excessive pumping.
Living at high altitude or smoking can increase red cell production, which may raise hematocrit. Tell your clinician if you recently changed altitude or are trying to quit smoking.
Diuretics can lower plasma volume and raise hematocrit. Testosterone and erythropoiesis-stimulating agents may increase red cells. Chemotherapy or some antibiotics can reduce production.
Pregnancy expands plasma volume and often lowers hematocrit. Newborns naturally have higher values that change over the first weeks of life; pediatric ranges are used for interpretation.
Recent bleeding, surgery, burns, or infections can change hematocrit through red cell loss or fluid shifts. Timing of the test relative to these events affects interpretation.
References