Creatinine Clearance (from Ankle-Brachial Index or Ankle-Brachial Pressure Ratio)
This test estimates how well your kidneys filter waste products by measuring blood pressure differences between your ankle and arm, often linked to circulation or vascular health.
["Assesses kidney function indirectly through blood pressure measurements in limbs."]
Key facts at a glance
- LOINC
- 35940-6
- Short code
- CT Ankle
- Synonyms
- CT Ankle
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct
- 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
Creatinine clearance is calculated using ankle-brachial index (ABI) or ankle-brachial pressure ratio (ABPR) measurements. These tests compare blood pressure at your ankle to that at your arm to estimate how efficiently your kidneys filter waste products. Unlike traditional creatinine clearance tests, this method focuses on vascular function rather than direct kidney filtration.
Why It’s Done
This test may be used to evaluate vascular health, especially in patients with suspected peripheral artery disease (PAD) or those at risk for kidney issues. It helps assess blood flow to your legs and may be part of a broader evaluation for conditions like diabetes, heart disease, or chronic kidney disease.
How It Works
You’ll have blood pressure measurements taken at your ankle and arm using a cuff. The difference in pressure helps estimate how well blood circulates to your lower limbs, indirectly reflecting kidney function and vascular health.
Preparation
No special preparation is needed. Wear comfortable clothing and avoid eating or drinking anything for 2–3 hours before the test if instructed by your provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
None
Frequently asked questions
A low ankle-brachial index (ABI) or abnormal ABPR may indicate poor circulation, which can affect kidney function indirectly. High ABI values may suggest calcified arteries. This test helps identify vascular risks that could impact kidney health or other systemic conditions.
What does a low ABI or ABPR mean?
Can I eat or drink before this test?
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 16, 2026. · Read our editorial policy