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Hematocrit (Calculated from Red Blood Cell Parameters)

Published: August 9, 2026Updated: August 17, 2026

This test calculates your blood’s hematocrit—a measure of red blood cell volume—using data from your red blood cell count and other blood components.

Quick summary

["Your hematocrit helps assess red blood cell health and overall blood health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
70168-0
Short code
Hct VFr Snv Calc
Synonyms
Hct VFr Snv Calc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
36
Ref high
50
Critical range
18 N/A – 60 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
calculated
CPT
85014
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is Hematocrit?

Hematocrit is the percentage of red blood cells in your total blood volume. It reflects how efficiently your blood carries oxygen. While not a standalone test, it’s often calculated from other blood tests like red blood cell count and hemoglobin levels.

Why Is It Measured?

This calculated value helps diagnose conditions like anemia (low red blood cells), polycythemia (high red blood cells), or dehydration. It’s also used in monitoring chronic diseases or blood disorders.

How Is It Done?

No special preparation is needed. A simple blood draw is taken, and your hematocrit is derived from automated blood cell analysis (often via a complete blood count, or CBC).

What Does It Tell Us?

While not a standalone result, it provides context for red blood cell health. Low hematocrit may signal anemia or fluid loss, while high levels could indicate overproduction of red blood cells or dehydration.

Reference range

Adult males: 38-50%; Females: 36-44%N/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Hct Calc

Frequently asked questions

What causes a calculated hematocrit to be checked?
Your doctor may order this calculation if you have symptoms like fatigue, shortness of breath, or pale skin, or if they suspect anemia, dehydration, or another blood-related condition.
Is there anything I should avoid before this test?
No special preparations are needed, but inform your doctor about any medications or recent blood donations, as they may affect results.
Can results change over time?
Yes, hematocrit can fluctuate with hydration, diet, exercise, or underlying health conditions. Regular monitoring helps track trends in your blood health.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 17, 2026. · Read our editorial policy