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Potassium (Serum) Rate Over 6 Hours

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

This test measures how quickly your potassium levels change in your blood over a 6-hour period, often used to assess kidney function or fluid balance.

Quick summary

["Understanding how potassium levels shift can help doctors diagnose or monitor conditions affecting your body’s fluid and electrolyte balance."]

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

Key facts at a glance

LOINC
18372-3
Short code
Potassium 6h Ur-sRate
Synonyms
Potassium 6h Ur-sRate
Category
electrolyte
Sample
urine
Container
Sterile urine container
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
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

Why Is This Test Done?

Your healthcare provider may order this test if you have symptoms like muscle weakness, irregular heartbeat, or signs of fluid imbalance. It helps track how well your kidneys are handling potassium over time.

What to Expect Before the Test

No special preparation is needed. You’ll have a blood sample drawn from a vein, usually in your arm. The process is quick and typically painless.

What the Results Mean

The test measures the rate of change in potassium levels, not absolute values. Results help determine if your body is losing or retaining potassium too quickly, which can affect heart rhythm or muscle function.

Common Conditions Monitored

This test is often used in patients with kidney disease, heart conditions, or those taking medications that affect potassium levels, such as diuretics or certain blood pressure drugs.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: urine

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Potassium Rate (6-hour)

Frequently asked questions

What causes a doctor to order this test?
A doctor may order this test if you have symptoms like unusual fatigue, muscle cramps, or an irregular heartbeat, or if you’re taking medications that can affect potassium levels.
How long does it take to get results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
You can eat and drink normally before the test, as no fasting is required.
  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