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24-Hour Urinary Potassium Excretion

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

This test measures how much potassium your body excretes in urine over a 24-hour period. It helps assess kidney function and electrolyte balance.

Quick summary

["Understanding your potassium loss can help identify kidney issues or electrolyte imbalances."]

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

Key facts at a glance

LOINC
9075-3
Short code
Potassium intake 1h
Synonyms
Potassium intake 1h
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
3.5
Ref high
5
Critical range
2.5 N/A – 6.5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84132
SNOMED
110742001
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

Potassium is an essential electrolyte that helps regulate heart rhythm, muscle function, and fluid balance. Your kidneys normally filter out excess potassium in urine. This test checks if your kidneys are removing enough potassium, which can reveal problems like kidney disease or certain medications affecting electrolyte levels.

How the Test Works

You’ll collect all your urine for a full 24 hours, typically starting after waking up and ending the next morning. The sample is then analyzed to determine the total potassium lost in urine.

Preparation

No special preparation is needed, but you should drink enough fluids to produce urine throughout the day. Avoid using diuretics (like caffeine or certain medications) unless approved by your doctor.

What to Expect

The test involves collecting urine in a container for 24 hours. You’ll need to keep a log of all urine output. Some labs may provide a urine collection kit with instructions.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24hr Potassium Urine

Frequently asked questions

What Might This Test Show?
Low potassium levels (hypokalemia) in urine may indicate kidney problems or excessive loss due to vomiting, diarrhea, or certain medications. High potassium levels could suggest kidney failure or improper kidney function.
How Does This Test Relate to My Health?
This test helps doctors diagnose conditions like chronic kidney disease, electrolyte imbalances, or side effects of medications. It’s especially useful if you have symptoms like muscle weakness, irregular heartbeat, or frequent urination.
Will I Need to Fast Before This Test?
No fasting is required for this test. However, follow your doctor’s advice about fluid intake and medications to ensure accurate 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