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Vitamin B7 (Biotin) 24-Hour Urinary Excretion Rate

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

This test measures how much biotin, a B vitamin, your body excretes in urine over 24 hours. Biotin helps with metabolism and nerve function.

Quick summary

["Understanding your biotin levels through urine excretion can help assess vitamin status or detect deficiencies."]

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

Key facts at a glance

LOINC
81018-4
Short code
Vit B7 intake 24h Measured
Synonyms
Vit B7 intake 24h Measured
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
measured
CPT
82670
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 Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like hair loss, skin rashes, nerve problems, or unexplained fatigue. It could also be used to monitor biotin levels in people with certain medical conditions or those taking medications that might affect biotin absorption.

What to Expect Before the Test

No special preparation is needed for this test. You’ll provide a 24-hour urine sample collected in a special container. Make sure to follow your provider’s instructions for accurate results.

How the Test Works

Your urine sample is analyzed to measure the amount of biotin excreted over 24 hours. This helps determine how much biotin your body is processing and eliminating.

What the Results Mean

Results may indicate whether your body is absorbing or processing biotin properly. Low excretion could suggest a deficiency, while high levels might indicate over-supplementation or certain medical conditions.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: serum

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

Short name

Biotin Urine Excretion Rate

Frequently asked questions

What causes a low biotin excretion?
Possible causes include poor diet, malabsorption issues, certain medications, or conditions like Crohn’s disease or alcoholism that interfere with vitamin absorption.
What does it mean if my biotin excretion is high?
High excretion could mean you’re taking biotin supplements in excess, have a metabolic disorder affecting biotin processing, or have conditions like pancreatitis that alter vitamin metabolism.
Do I need to change my diet before this test?
No dietary changes are typically required unless your provider specifically instructs you to do so. However, avoid excessive biotin supplements unless advised.
  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