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Phenotypic Resistance Testing for Protease Inhibitors (Lopinavir)

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

This test helps determine how your body may respond to the protease inhibitor medication lopinavir by measuring its resistance to certain viral enzymes. It’s used to guide treatment decisions for HIV infection.

Quick summary

["This test assesses lopinavir resistance through viral enzyme activity, aiding personalized HIV treatment planning."]

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

Key facts at a glance

LOINC
57997-9
Short code
Lopinavir+Ritonavir Islt Phenotyp
Synonyms
Lopinavir+Ritonavir Islt Phenotyp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenotyping
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 lopinavir (a medication used to treat HIV) and suspect resistance to the drug. It helps ensure the medication remains effective by checking how well the virus is inhibited by lopinavir’s protease enzyme.

What to Expect Before the Test

No special preparation is needed. A blood sample is typically drawn from a vein in your arm. If you’re on HIV treatment, your provider may discuss timing with you to avoid interference from recent medications.

What Happens During the Test

The test involves analyzing a sample of your blood or saliva to measure the virus’s ability to resist lopinavir. Results are compared to a reference range to determine resistance levels, often reported as a ratio or index.

What the Results Mean

Results indicate whether the virus is likely resistant to lopinavir, which can guide adjustments to your treatment plan. High resistance may prompt a switch to a different protease inhibitor or combination therapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lopinavir Phenotype Test

Frequently asked questions

Will this test affect my current medications?
This test itself does not change your medications, but the results may influence future treatment decisions. Always follow your healthcare provider’s guidance regarding any adjustments to your regimen.
How long will it take to get my results?
Results are typically available within 1–2 weeks, depending on your lab’s processing time. Your provider will contact you once results are ready.
Can I still take lopinavir if the test shows resistance?
If resistance is detected, your provider will discuss alternative protease inhibitors or combination therapies to improve treatment effectiveness. Never stop or change medications without medical advice.
  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