Red Blood Cell Area Ratio (Mean Corpuscular Area Index)
This test measures the average size of red blood cells, expressed as a ratio, which can help assess red blood cell health and potential blood disorders.
["This test helps evaluate red blood cell morphology and may indicate conditions like anemia or iron deficiency."]
Key facts at a glance
- LOINC
- 13945-1
- Short code
- RBC #/area UrnS HPF
- Synonyms
- RBC #/area UrnS HPF
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- microscopy-light-hpf
- CPT
- 85041
- SNOMED
- 900000000000003001
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What Does This Test Measure?
The test calculates the mean corpuscular area (MCA) as part of a ratio, reflecting the typical size of your red blood cells. While not a standalone measurement, it’s often used alongside other blood tests like mean corpuscular volume (MCV) to diagnose conditions affecting red blood cell production or shape.
Why Might This Test Be Ordered?
Your healthcare provider may order this test if they suspect conditions like microcytic anemia (small red blood cells), macrocytic anemia (large red blood cells), or other blood disorders. It may also be part of a broader evaluation for unexplained fatigue, pale skin, or other symptoms.
How Is This Test Performed?
A small blood sample is drawn from a vein, typically in your arm. The sample is analyzed in a laboratory to measure the size distribution of your red blood cells. Results are compared to standard reference ranges to identify any deviations.
What Are Common Causes of Abnormal Results?
Abnormal RBC area ratios may signal underlying conditions such as iron deficiency, vitamin deficiencies (e.g., B12 or folate), chronic diseases, or certain blood disorders. Low ratios could indicate microcytosis, while high ratios may suggest macrocytosis.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test provides indirect insight into red blood cell morphology and is often used in conjunction with other blood tests (e.g., MCV, hemoglobin) to guide diagnosis. It is not a standalone diagnostic tool but supports evaluation in suspected anemia or blood disorders.
Short name
RBC Area Ratio Test
Frequently asked questions
What does an abnormal RBC area ratio mean?
Will I need to prepare for this test?
How long will it take to get results?
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