TB skin test in Puerto Rico: how it works and how long it takes

The tuberculin skin test, also called a PPD or Mantoux test, checks whether you have been exposed to the bacteria that cause tuberculosis (TB). PPD stands for purified protein derivative: the fluid injected just under the surface of the skin on your forearm. You feel a brief sting, and a small bump forms that goes away within hours.

The test isn’t read on the same day. You must go back 48 to 72 hours later so a health professional can look at and measure the reaction on your arm. A health worker reads it, not you.

Most people look for a TB skin test in Puerto Rico because their job requires the health certificate (certificado de salud). According to the Department of Health guide, which reproduces Regulation 138:

• The skin test is placed by the doctor authorized to issue health certificates or their designated professional nursing staff.
• It must be read 48 to 72 hours after it is placed.
• The TB test must be from within the 3 months before the certificate date; the syphilis test, within 6 months. Older results don’t count.
• Instead of the skin test, you can use an FDA-approved TB blood test, processed by a clinical lab the Department of Health authorizes.
• The authorized doctor interprets the results, and the certificate is valid for one year.

If you don’t know where to go, ask your employer or call the Health Certificates Division at 787-765-2929, ext. 4759 (Spanish).

We do not place or read the TB skin test and do not issue the health certificate: the authorized doctor does that in person. What we do is the lab order for the blood tests.

In a School and work forms visit (US$35), Dr. Diana Nieves Castro, MD, a Puerto Rico-licensed general practice physician, evaluates you by video and, if appropriate, gives you the lab order for the syphilis test and, if you choose it, the TB blood test, so you arrive at the lab with the order in hand. Details are on work and school medical certificate.

• Request your visit. On the booking page, choose School and work forms. Request a visit online 24/7 — we confirm your time by email or text.
• See the doctor by video. We send you a secure video link; it works on your phone, tablet or computer. You must be in Puerto Rico during the visit.
• Get tested at a clinical lab the Department of Health authorizes, then go to the authorized doctor for the evaluation, the skin test if you use it, and the certificate.

Before you get tested, confirm with the authorized doctor that they accept results from an authorized lab ordered by another doctor. You pay by card when you request the visit, and you get a full refund if the visit can’t take place. The lab and the authorized doctor charge separately. If the patient is under 21, a parent with patria potestad or a legal guardian stays on the video for the whole visit and shows photo ID.

The Department of Health guide doesn’t mention fasting for the health certificate. According to MedlinePlus, the TB skin test needs no special preparation, and it lists no fasting for the syphilis test (VDRL).

If your order includes other tests, or your lab gives you other instructions, follow them. Before the skin test, say whether you have ever had a positive TB test, take medicines that weaken the immune system, or received the BCG vaccine against TB.

Besides the TB test, the Department of Health guide requires a medical evaluation on an official form and a syphilis test. For people who produce, handle or store food, the doctor may also order a throat or stool culture, at their discretion. All the requirements are in the health certificate in Puerto Rico guide.

Both count for the health certificate. The skin test takes two visits: one to place it and one to read it. The blood test (IGRA) is a single sample at the lab.

According to the CDC, the blood test is preferred for people who received the BCG vaccine, because BCG can cause a false-positive skin test and does not affect the blood test. Ask your lab whether it offers the blood test and what it costs.

A positive test means you have TB bacteria in your body, but it doesn’t tell whether the disease is active. According to the CDC, more tests are needed, such as a chest X-ray and sometimes a sputum test. The Department of Health guide says that if the skin or blood test is positive, the doctor orders a chest X-ray.

Positive results are reported to the Regional Epidemiology Office, and for the certificate you must show evidence that you were evaluated and treated at the epidemiology clinic. If you have had a positive skin test before, tell the doctor: it usually isn’t repeated.