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Hemoglobin A1c (HbA1c) with 24-hour urine collection for creatinine clearance

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

This test measures your long-term blood sugar control and assesses kidney function by combining hemoglobin A1c with a 24-hour urine creatinine clearance measurement.

Quick summary

["Helps track diabetes management and kidney health in one combined assessment."]

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

Key facts at a glance

LOINC
18278-2
Short code
Hgb F Mec Ql Apt-Downey
Synonyms
Hgb F Mec Ql Apt-Downey
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
apt-downey
CPT
85018
SNOMED
900000000000003004
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 Is Done

Your healthcare provider may order this test if you have diabetes to monitor how well your blood sugar is controlled over time. It also evaluates kidney function by measuring how well your kidneys filter waste products, including creatinine, from your urine over 24 hours.

How the Test Works

The test involves two parts: a blood draw to measure hemoglobin A1c (which reflects average blood sugar levels over the past 2–3 months) and a 24-hour urine collection to measure creatinine clearance, which estimates kidney function.

Sample Collection Process

For the blood test, a small sample of your blood is taken from a vein. For the urine test, you’ll collect all urine for a full 24-hour period in a special container. Follow your provider’s instructions carefully to ensure accurate results.

What to Expect Before the Test

No special preparation is needed for the blood draw, but you should avoid smoking or caffeine 30 minutes before the test. For the urine collection, drink plenty of fluids and empty your bladder before starting to ensure proper timing.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c + CrCl (24h urine)

Frequently asked questions

What does an abnormal result mean?
An elevated HbA1c suggests poor blood sugar control, which may indicate uncontrolled diabetes. A reduced creatinine clearance may signal kidney issues, especially in people with diabetes. Both findings require medical evaluation to determine next steps, such as adjusting medications or monitoring closely.
How often should I get this test?
Your provider will determine the frequency based on your diabetes management plan. Typically, HbA1c is checked every 3–6 months, and creatinine clearance may be reviewed if kidney function is suspected to be affected.
Can diet or exercise affect these results?
Yes. Blood sugar levels can be influenced by diet, exercise, and medications, so your HbA1c may vary. For creatinine clearance, hydration and kidney health generally affect urine output, so consistency in urine collection is key.
  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