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5-Alpha Reductase Activity, 24-Hour Urine — Mass Rate

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

A specialized 24-hour urine test that measures 5-alpha reductase activity, an enzyme involved in converting testosterone to dihydrotestosterone.

Quick summary

["This test may help evaluate reduced 5-alpha reductase activity when an androgen-related developmental concern is present."]

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

Key facts at a glance

LOINC
57614-0
Short code
5-A THF pre hi Dex 24h Ur-mRate
Synonyms
5-A THF pre hi Dex 24h Ur-mRate
Category
liver
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 is this test?

This test measures 5-alpha reductase activity in urine collected over 24 hours. This enzyme helps convert testosterone into dihydrotestosterone, which is important for male genital development and other androgen-related functions.

Why might I need this test?

It may be ordered when reduced 5-alpha reductase activity is suspected, particularly during evaluation of differences in external genital development in a newborn or incomplete virilization later in life. It is a specialized test and is usually interpreted with other laboratory and clinical findings.

How is the test performed?

Urine is collected into a designated container for a full 24-hour period. The laboratory measures the amount of 5-alpha reductase activity or related metabolites and reports the result as a mass rate based on the urine collected.

How do I prepare for the test?

Follow the laboratory's 24-hour urine collection instructions, including the start and end times and how to store the container. Tell your clinician about testosterone, steroids, antiandrogens, hormonal contraceptives, and supplements, because these can affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urine 5-Alpha Reductase

Frequently asked questions

Why is a 24-hour urine collection required?
The test measures activity or metabolites throughout the day. Collecting all urine for the specified period provides a more representative result than a single urine sample.
Does an abnormal result confirm a genetic condition?
No. An abnormal result may support reduced enzyme activity, but a clinician may also need physical examination results, hormone testing, and sometimes genetic testing to determine the cause.
What if part of the urine collection is missed?
Tell the laboratory or your clinician, because an incomplete collection can make the result unreliable. The collection may need to be repeated using the provided instructions.
  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