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Glomerular Filtration Rate (GFR) by Modified Dietary Ingestion Method (serum/plasma)

Published: August 9, 2026Updated: August 16, 2026

This test estimates how well your kidneys are filtering waste from your blood using a modified approach that considers how much you eat and drink.

Quick summary

["A GFR test helps doctors assess kidney function and identify early signs of kidney disease."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
11939-6
Short code
GA from rad len.Merz.87
Synonyms
GA from rad len.Merz.87
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-radius-length-merz
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

Why This Test Matters

Kidneys normally filter waste products and excess substances from your blood through tiny filters called glomeruli. GFR measures how effectively this filtering happens. While traditional GFR tests rely on blood creatinine levels, this method uses dietary intake to provide an alternative estimate, especially useful in certain clinical contexts.

How It Works

Instead of measuring blood creatinine alone, this test accounts for how much protein and fluid you consume. Your healthcare provider calculates GFR based on your serum/plasma sample and your reported dietary intake over a set period.

What to Expect

You’ll need to provide a blood sample (serum or plasma) and report your typical dietary habits (protein and fluid intake) for the test period. This may involve a short dietary log or interview with your provider.

Common Uses

This test may be used to evaluate kidney function in patients with conditions that affect dietary protein intake, such as certain metabolic disorders or those on specialized diets. It can also help monitor kidney health in patients with chronic conditions requiring careful dietary management.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

GFR (Dietary Method)

Frequently asked questions

What questions might you have about this test?
This test provides an alternative way to estimate kidney function when traditional GFR methods may not be straightforward. It can be particularly useful in patients with dietary restrictions or those who require precise dietary monitoring for their health condition.
How accurate is this GFR test compared to standard methods?
Like all GFR tests, this method relies on your reported dietary intake, which can vary. Accuracy depends on how closely you follow your dietary records. Your healthcare provider will compare results with standard methods if needed to confirm findings.
Can I eat or drink anything special before this test?
No special preparation is required. Focus on reporting your usual dietary habits (protein and fluid intake) accurately, as this is critical for the test’s accuracy. Avoid unusual dietary changes before the test to ensure reliable results.
  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 16, 2026. · Read our editorial policy