The Deal with PrEP Labs

Know exactly what is tested for and why when taking PrEP.

July 12, 2021
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This article was updated by the FOLX Editorial Team on 9/29/23.

PrEP stands for Pre (before) Exposure (coming into contact with something) Prophylaxis (prevention of disease). PrEP describes a way of taking a once-daily anti-HIV medication that reduces the risk of acquiring HIV through sex by 99% and through IV drug use by 74% when taken as directed. Truvada and Descovy are the brand names most associated with PrEP, but all FDA-approved pills for PrEP contain the same antiretroviral medicines: tenofovir and emtricitabine. When someone says they are taking PrEP, that usually means they are taking an approved medication, getting regular lab tests to check in on their health, and are in contact with a healthcare provider about their health concerns.

Why do we need labs?

PrEP requires monitoring of HIV status, kidney function, and Hepatitis B status in order to start and continue the medication. Because of how PrEP interacts with the body and other medications, there are a few things we need to keep track of.

We test for HIV to start or restart PrEP and then every three months.

PrEP is designed to help people remain HIV-negative, so it is important to know your HIV status as you start or continue the medication. PrEP isn't a complete regimen to manage HIV, and there is a risk of drug resistance to HIV medication if taking PrEP despite HIV infection. Resistance to PrEP means that it is no longer as effective in preventing the transmission of HIV. This is more likely to occur while taking PrEP only some of the time. For example, if you take PrEP only a few times a week and you get HIV but continue taking PrEP, the virus can become resistant to the medication. Drug resistance is more likely to happen during undiagnosed acute HIV infection.

There are two different types of HIV tests:

  1. Third-generation HIV tests. This test checks for the antibodies made by the immune system to fight off HIV. It takes time for the body to produce antibodies, which is why this test can stay negative for up to three months after contracting HIV. Saliva tests and certain finger prick tests are third-generation tests.
  2. Fourth-generation HIV tests. FOLX offers this type of test, which checks for both antibodies and antigens. This test detects HIV infection much earlier than the third-generation tests. If this test comes back positive and there's enough blood left on the sample, a second test is done to confirm HIV status.

Labs are required to report positive HIV test results to your local Department of Health. They will contact you to see if you have been connected with HIV care and will ask about recent sexual partners to make sure they also have access to testing and care. You decide what and how much information you want to give them. This type of reporting is actually quite common, and is also required for other infections such as chickenpox, gonorrhea, Lyme disease, tetanus, and several others.

We also closely monitor kidney function (creatinine test) to start or restart PrEP, then every six to twelve months thereafter.

Medications containing tenofovir -- like those approved for PrEP (TDF/FTC) -- are removed from the body by the kidneys. It is normal to see slight decreases in kidney function. In the small number of patients (approximately one in 200) who see a significant reduction in kidney function, these changes are usually reversed after stopping the medication. However, the medication worsens kidney failure for folks who already have kidney problems. Kidney failure can also happen for those with other health conditions or who take medications that affect the kidneys. People interested in PrEP should have a baseline and periodic kidney function tests.

We check for Hepatitis B to start or restart PrEP.

We check for hepatitis B before starting PrEP. While PrEP can be used to treat hepatitis B infection, stopping PrEP with an active hepatitis B infection can, in very rare cases, lead to liver inflammation or liver failure. Our test looks for a current hepatitis B infection. Other tests can tell if you're immune to hepatitis B. If you are immune, you can't be infected with hepatitis B, and you don't need any more testing done.

What other labs and tests do we recommend?

At FOLX, we only want to run labs necessary for the care we provide so we can keep costs low for members. PrEP comprises one part of our members' sexual health toolkit. If relevant to you, other tests to consider are quarterly screening tests for chlamydia, gonorrhea, and syphilis and annual screening tests for hepatitis C.

FOLX pairs lab results with our members' lived experiences to come to final medical decisions.

At FOLX, we do not base medical decisions solely on labs. It is much more important to hear from our members about how they are feeling. We will communicate with our members about any lab results and if there are any concerns from a medical perspective. We want to hear from members about what feels right in their bodies and how they want to move forward before finalizing any changes.

FOLX wants to make getting labs done easy.

FOLX offers three different options to keep on top of PrEP labs. 

  • Go to a Quest Diagnostics. FOLX will order labs to a member's nearest Quest Diagnostics PSC (Patient Service Center) to go and get blood drawn in person. Quest will send lab results directly to FOLX.
  • At-home lab kits. FOLX will ship a finger-prick kit directly, and members are required to deposit a finger-prick blood sample and then send the kit back to our partner lab by mail.
  • Get and send your own labs. If it's easier to have insurance pay for labs, or a member has an existing clinic that will order labs for them, then labs can uploaded and sent to FOLX.

a PrEP lab work cost chart FOLX Health

So, that’s it for PrEP labs. FOLX is currently able to prescribe PrEP to be shipped directly to members! For existing FOLX members, don't hesitate to schedule time with a clinician. For those who want to know more, check out our sexual health services, and search the Sexual Health category to read more in the Library.


FOLX Health is the first digital healthcare company designed by and for the LGBTQIA+ community. Our services include virtual primary care, gender-affirming hormone therapy including estrogen and testosterone (HRT), mental health care, sexual and reproductive health care, preventive care, and fertility consultations. FOLX memberships give you access to LGBTQIA+ expert clinicians, peer support, thousands of LGBTQIA+ resources, and more. Whether you’re lesbian, gay, bisexual, transgender, queer, gender non-conforming, or nonbinary, you can find LGBTQIA+-specialized health care that helps you meet your wellness goals. FOLX Health is health care that's queer all year. Get all the benefits of becoming a FOLX member and sign up today!

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