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Serum/plasma concentration of furosemide (a loop diuretic)

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

This test measures the amount of furosemide, a medication used to help your body remove excess fluid, in your blood.

Quick summary

["Understanding your furosemide levels helps doctors monitor how well your body is responding to this medication."]

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

Key facts at a glance

LOINC
73017-6
Short code
Furosemide (neut) IgM SerPl Ql FC
Synonyms
Furosemide (neut) IgM SerPl Ql FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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’re taking furosemide to manage conditions like high blood pressure, heart failure, or kidney problems. It helps ensure the medication is working properly and adjusts your dose if needed.

What to Expect Before the Test

No special preparation is usually required, but you may be asked to fast for a few hours before the blood draw if your test involves a specific timing (e.g., 24-hour urine collection). Always follow your provider’s instructions.

How the Test Is Performed

A healthcare professional will draw blood from a vein in your arm. You may feel a small pinch, but it’s typically over quickly. The blood is then sent to a lab for analysis.

What the Results Mean

Results help your doctor assess whether your furosemide dose is too high or too low. Very high levels might indicate poor kidney function or overmedication, while very low levels could mean the medication isn’t working as intended.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Monitoring Diuretic Effectiveness

Short name

Furosemide Level

Frequently asked questions

Why might my doctor ask for this test?
Your doctor may check furosemide levels to ensure it’s helping with fluid retention, to prevent side effects like low blood pressure or electrolyte imbalances, or to adjust your dose if you’re not responding well.
What do my results tell me about my health?
While this test focuses on the medication itself, abnormal levels may signal underlying issues like kidney problems or how your body processes drugs. Always discuss results with your provider for personalized insights.
Can I eat or drink before this test?
Check with your doctor or lab about fasting rules, as some tests (like furosemide levels) may require timing around meals or hydration. General blood tests don’t need fasting, but follow their guidance.
  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