Mountain West · HIV 4th Generation Antigen/Antibody Test
HIV 4th Generation Antigen/Antibody Test in Colorado
HIV 4th Generation Antigen/Antibody Test can be ordered without a referral from your own doctor, and this guide covers what to expect. The HIV 4th Generation Antigen/Antibody Test screens for both HIV antibodies and the p24 antigen, offering earlier detection than older antibody-only tests.
Lab requirements in Colorado
Here is what you need before ordering and completing the HIV 4th Generation Antigen/Antibody Test in CO. Review each item and confirm the details with the collection lab.
- Physician's order
- Included. A physician's order is required for lab testing and is provided for you by our partner's physicians — no referral from your own doctor is needed.
- Fasting
- Some tests require fasting or avoiding certain foods or drinks beforehand. You will be informed when you order — confirm the details with the collection lab.
- Preparation
- No special preparation is typically required, but always follow the specific instructions provided by the collection lab or your healthcare provider. This may include timing considerations…
- Sample & visit
- A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
- Identification
- Bring the lab requisition form from your account. The collection lab may also ask for a government-issued photo ID.
- Turnaround
- 1-3 business days
- Availability
- Our partner lab does not serve ND, RI, NY, NJ, MD or HI. Confirm availability for your location with the collection lab.
Before you go
- Order your test before visiting a lab, then use the requisition form in your account.
- Print the requisition form, or fax it to the lab directly from your account.
- No scheduling is needed — visit the collection lab during its normal business hours.
- A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
- Bring a government-issued photo ID in case the lab requests it.
- Results are posted to your secure account within 1–3 business days.
Requirements are summarized from our partner lab's published policies. Preparation and availability can change — confirm current instructions with the collection lab before your visit.
What this test is
This test is a combination immunoassay that looks for two markers of HIV: antibodies produced by the immune system and the p24 antigen, a protein from the virus itself. It is often called a fourth-generation or DUO test because it detects both targets in one assay. It does not diagnose AIDS or measure viral load.
What it measures
- HIV-1/2 antibodies — Reflects the immune system's response to HIV infection.
- p24 antigen — A viral protein that can appear earlier than antibodies after infection.
What the test involves
A healthcare professional collects a small sample of blood, usually from a vein in your arm, using a standard blood draw. The sample is then sent to a laboratory for analysis.
Why it is often ordered
A clinician may order this test as part of routine screening, after a potential exposure, or when someone has symptoms that could be related to HIV. It is also used to monitor people at ongoing risk.
Preparation
No special preparation is typically required, but always follow the specific instructions provided by the collection lab or your healthcare provider. This may include timing considerations after a possible exposure.
How results are reported
Results are reported as reactive or non-reactive, and sometimes as indeterminate, based on the lab's cutoff values. Reference ranges and interpretation criteria vary by laboratory, so your provider will explain what your result means in your situation.
Before you go
- Whether any special timing or preparation is needed before your blood draw.
- How long it will take to receive your results and how they will be shared.
- Whether follow-up testing or counseling is included if your result is reactive.
Cities
HIV 4th Generation Antigen/Antibody Test in Colorado communities
Choose your city for local context and to order this test.