The Body: The Complete HIV/AIDS Resource
Follow Us Follow Us on Facebook Follow Us on Twitter Download Our App 
Professionals >> Visit The Body PROThe Body en Espanol
For World AIDS Day, read about stigma, criminalization and more >>
Ask the Experts About

Safe Sex and HIV PreventionSafe Sex and HIV Prevention
Rollover images to visit our other forums!
Recent AnswersAsk a Question
  • Email Email
  • Glossary Glossary

Was I misinformed??? (NAT TESTING 2008)

Aug 1, 2008

Hey Dr. Bob, I'll be brief. I recently donated blood and requested to come in and pick up my results. Everything came back negative and the Director of the Lab told me that they use the HIV antibody test as well as the HIV NAT to screen donated blood. She said that the HIV NAT picks up infection anywhere from 10-15 days past acquiring the virus. Do you know if this is true or not? I donated blood 18 days past my last sexual encounter. Would the HIV NAT have picked up infection by then? I was just wondering if what the woman at the lab told me was true. Thanks and keep up the GREAT work!

Response from Dr. Frascino


Please note that the purpose of the testing done at blood donation sites is to protect the blood supply, not diagnose HIV infection. NAT testing can pick up some HIV infections prior to standard HIV-antibody tests. (See below.) I certainly hope you were not using the blood donation service as a means of checking your HIV status after your sexual encounter 18 days ago. If you had any worry whatsoever that you might be HIV infected, you would not have donated blood, right?

Dr. Bob

NAT Testing Apr 26, 2008


I had a possible exposure to HIV on or around March 19. I made a major mistake by having unprotected sex with a stranger. He later told me he was HIV positive and has since changed his cell phone number, so I was unable to confirm if he was indeed positive nor was I able to get further information about viral load etc.

I waited until April 3rd to get tested. I live in Los Angeles and was fortunate enough to receive free NAT testing. Additionally, I was screened for all STDs. Everything came back negative. The counselor said that I am 100% negative as of March 13 (before the possible exposure) and assured me that I should feel confident about my negative result being conclusive. My question is how good should I feel about the 15 days I waited before getting the NAT test? Do you have any statistics around how long it takes for the virus to present itself?



Response from Dr. Frascino

Hello Eric,

The current testing guidelines still recommend HIV-antibody testing at the three-month mark. Other more sensitive tests are being developed and coming online; however, the formal guidelines have not yet been revised, as we are still gaining information about the sensitivity and specificity of the newer tests. NAT allows us to detect very small amounts of genetic material (DNA or RNA) via a process called amplification, which involves massive copying. In laboratory studies NAT testing reduced the time to viral detection to 12 days. So is your 15-day negative NAT WOO-HOOable? Honestly I don't know. There has not been enough published research for me to make that a definitive statement. I'd still recommend the 3 month antibody test.

Dr. Bob

NAT test Aug 5, 2007

Dr. Bob, some states actually use a nat test along with an antibody test to check subjects for hiv. They take two viles of blood for this. Can you tell me what a nat test checks for ?

Response from Dr. Frascino


Sure. See below.

Dr. Bob

nucleic acid testing May 16, 2006

dr. bob, i'm a 25 year old guy who made a mistake and had brief unprotected insertive anal sex about 5 weeks ago. The guy also had his penis around my anus- but not in. Of course, I'm beating myself up and my anxiety is really kicking up right now. I had an hiv test and std screenings at one week. All negative/non reactive. My anxiety got very bad and my dr. recommended having a nucleic acid test at 3 weeks if that was the case. I found a program at the los angeles gay and lesbian center that offers free diagnostic nat for hiv. I went about 10 days ago and get the results tomorrow. I know you don't recommend this as a means of diagnosis, but I wanted to know what you know of the testing they offer and whether or not it is reliable. also, is the chance for a false positive still high as i believe it is a pooled nat test?

whether or not you answer this, thanks for all your help and support, you've gotten me through a scare once before and hopefully i'm a day away from woohooing again. or at least a woo. you really are an angel.

Response from Dr. Frascino


Yes, I am aware the Gay and Lesbian Center in Los Angeles began offering free nucleic acid amplification testing (NAT). I believe they are the first site in Los Angeles County to do so! By report, this testing assay, which detects actual HIV rather than antibodies to the virus, can give accurate results within three to four weeks, compared to three months for standard HIV-antibody tests, such as ELISA. I do not have specific information about the rate of false-negatives or false-positives for the specific testing assay the center is using. However, chances are the folks at the center would be able to provide you with whatever information has been generated so far. I do believe the general testing assay (NAT) is indeed valid. More information should be available fairly soon if this type of testing becomes more widespread and available. I'll try to keep you posted as reliable information evolves.

Good luck!

Dr. Bob

Three New Assays Approved

May 25, 2007

On May 23, 2007, FDA approved the Procleix Ultrio Assay on the fully automated Procleix TIGRIS system manufactured by Gen-Probe Inc., of San Diego, California, and marketed by Chiron Corporation. This is a fully automated qualitative in vitro nucleic acid test (NAT) to screen for human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) RNA in donated blood from donors of whole blood, blood components, or source plasma. It is also licensed to screen individual organ donations from living donors, heart-beating organ donors, and cadaveric (non-heart-beating) organ donors. The capability of full automation will reduce human error and accelerate blood screening, enhancing blood safety.

On May 11, 2007, FDA granted marketing approval to two HIV-1 PCR assays for use in managing the treatment HIV infection.

The Abbott RealTime HIV-1 Assay, made by ABBOTT Molecular, Inc., is an in vitro reverse transcription-polymerase chain reaction (RT-PCR) assay for the quantitation of Human Immunodeficiency Virus type 1 (HIV-1) on the automated m2000 System in human plasma from HIV-1 infected individuals over the range of 40 to 10,000,000 copies/mL. The Abbott RealTime HIV-1 assay is intended for use in conjunction with clinical presentation and other laboratory markers for disease prognosis and for use as an aid in assessing viral response to antiretroviral treatment as measured by changes in plasma HIV-1 RNA levels. (Product label)

The COBAS AmpliPrep/COBAS TaqMan HIV-1 Test, made by Roche Diagnostics is an automated PCR test, indicated for the quantitation of Human Immunodeficiency Virus Type 1 (HIV-1) nucleic acid in human plasma (viral load) for use in conjunction with clinical presentation and other laboratory markers. The test is intended for use in conjunction with clinical presentation and other laboratory markers of disease progress for the clinical management of HIV-1 infected patients. It can be used to assess patient prognosis by measuring the baseline HIV-1 RNA level or to monitor the effects of antiretroviral therapy by measuring changes in plasma HIV-1 RNA levels during the course of antiretroviral treatment. (Product label)

Neither the Abbott RealTime nor the COBAS AmpliPrep/COBAS TaqMan HIV-1 assay is intended to be used as a donor screening test for HIV-1 or as a diagnostic test to confirm the presence of HIV-1 infection.

blood donation and notification May 18, 2006

Hey doc, Just wanted to say before i ask my question, that you provide a wonderful service and should be commended for your expertise and sacrifice. My question is this: About two weeks ago, i donated blood. I dont consider myself at risk, and i answered all questions honestly. Anyway, the other day, i called the blood bank to see if and when i could donate again. The woman on the phone gave me a date and the conversation ended. (I must admit that i had two motives in makeing this call. I would like to donate again, but i also wanted to know the status of my blood) Would the womans prompt response of my eligibility date mean that my blood has been approved for use?(I gave her my blood number, name, and date of birth) Finally, if my blood tested positive for anything, how long would it be until i was contacted about it? Lastly, how would the red cross notify me of any possible condition? (mail, telephone, etc.) Thank you for all of your help in this matter.

Response from Dr. Frascino


If you don't consider yourself at risk and answered all the questions honestly, I don't understand why you had a second motive for your call.

If, on the other hand, you have cause to be even slightly concerned that you may be HIV positive and decided to give blood anyway because you "wanted to know the status of my blood," that is unconscionable and immoral and you should be ashamed of yourself. Since I strongly hope this is not the case, I'll simply advise you that since you do not consider yourself at risk and answered all the questions honestly, you have absolutely nothing to worry about. Right?

Dr. Bob

Giving false hopes?
Alcohol and meds

  • Email Email
  • Glossary Glossary

 Get Email Notifications When This Forum Updates or Subscribe With RSS



This forum is designed for educational purposes only, and experts are not rendering medical, mental health, legal or other professional advice or services. If you have or suspect you may have a medical, mental health, legal or other problem that requires advice, consult your own caregiver, attorney or other qualified professional.

Experts appearing on this page are independent and are solely responsible for editing and fact-checking their material. Neither nor any advertiser is the publisher or speaker of posted visitors' questions or the experts' material.

Review our complete terms of use and copyright notice.

Powered by ExpertViewpoint