Calculated Hematocrit Ratio (from Plasma/Red Blood Cell Parameters)
This test calculates a derived measure of red blood cell volume relative to plasma using blood sample data. It may be used to assess overall red blood cell distribution or to support further diagnostic evaluation.
["A calculated ratio helps doctors understand red blood cell and plasma balance in your blood."]
Key facts at a glance
- LOINC
- 70169-8
- Short code
- Hct VFr Plr Calc
- Synonyms
- Hct VFr Plr 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 This Test Measures
The test uses mathematical calculations based on your blood sample to determine a ratio involving hematocrit (the proportion of red blood cells in your blood) and related measurements. While not a standalone diagnostic test, it may be part of a broader evaluation for conditions affecting red blood cells, fluid balance, or blood health.
Why It Might Be Ordered
Your healthcare provider may order this test if they suspect conditions like anemia, polycythemia, dehydration, or other blood-related disorders. It can also be part of routine monitoring for patients with chronic conditions affecting red blood cells or fluid balance.
Sample Collection and Preparation
A blood sample is drawn from a vein, typically in your arm. The sample is processed to separate plasma and red blood cells. The test relies on automated calculations using these components to derive the ratio.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours if your test includes fasting components (though this test itself does not require fasting). Wear comfortable clothing and bring any medications you’re currently taking.
Reference range
Adult males: 38-50%; Females: 36-44%N/A
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
Frequently asked questions
What does this test measure exactly?
No special dietary restrictions apply to this test itself, but if your healthcare provider ordered related tests (e.g., glucose levels), follow their fasting instructions. Otherwise, standard hydration is fine.
Frequency depends on your healthcare needs. This test may be part of routine monitoring for chronic conditions or ordered periodically if you have risk factors for blood disorders. Follow your provider’s guidance.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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