Ask Dr. H: Alternatives to standard TB skin test

Question:

Before starting school, I had to have a "PPD skin test" to check to see if I was ever exposed to tuberculosis. Why couldn't I just have a blood test to check for this, similar to HIV or herpes tests? Or what about just getting a chest X-ray?

Answer: Actually, there is a blood test available through Quest Diagnostics, LabCorp and other labs: the QuantiFERON-TB Gold In-Tube (QFT-GIT) test. While I've not personally used the test, it does have several advantages over traditional PPD tuberculin skin testing.

First, the traditional PPD skin test requires a second visit to the doctor's office after 48 to 72 hours to check the site where the test was administered for any reactivity. Second, PPD skin tests can sometimes be interpreted falsely as being positive - especially with those who have received the BCG vaccine (inconsistently effective as a worldwide vaccine, it uses a cousin of the tuberculosis bacteria to induce immunity) because they come from countries such as India where tuberculosis is endemic. Third, falsely negative PPD tests can occur in folks who are seriously ill or immune-suppressed.

The QFT-GIT requires a single blood draw, and can distinguish between prior BCG vaccine exposure (Mycobacterium bovis) and latent tuberculosis infection from Mycobacterium tuberculosis. False negative test results are unlikely to occur as well. The main drawback to performing blood testing for latent tuberculosis is that the specimen must be received and tested by the lab within 14 hours, which is not always possible.

A chest X-ray can identify active tuberculosis in the lungs but cannot identify quiescent, previously untreated tuberculosis. So a normal chest X-ray does not exclude TB disease.

Q:

Could you please tell me why I get muscle spasms or a charley horse in my stomach on the front right side under my rib cage whenever I bend to put on my stockings or tie my shoes? It even happens sometimes when I'm sitting.

A: What you're describing is commonly called a "stitch" in the side. It's a cramping of the diaphragm, the dome-shaped muscle that separates the abdominal cavity from the chest cavity. The job of the diaphragm is to help inflate and deflate the lungs. When we inhale, the diaphragm moves down; when we exhale, the diaphragm moves up.

The most common cause of a diaphragm cramp is rapid, shallow breathing that occurs with running or jogging. The liver, located in the right upper part of the abdomen, is attached to the diaphragm by ligaments. Part of the stomach is there as well. With running or jogging, the diaphragm is stretched and strained by the slight bouncing of these organs. It makes perfect sense, then, that "stitches" generally occur on the right side.

While your diaphragm cramping had nothing to do with jogging or running, the act of bending encourages shallow breathing and a stretching of the diaphragm muscle. How do we prevent them? Runners or joggers should avoid shallow breathing or hyperventilating. If you're exhausted, stop and catch your breath. Deep breathing will help prevent cramping. Drinking fluids, especially drinks such as Gatorade or Powerade that replace not only fluid but electrolytes, will help.

Dehydration is one of the most common causes of fatigue, and that can lead to cramps. Specifically in your case, try deep breathing through pursed lips (as if you're blowing out candles) while bending over or if you feel a stitch coming on.

By the way, did you ever wonder why those pesky leg cramps are called a "charley horse"? It's named after the 1880s baseball Hall of Fame pitcher Charles "Old Hoss" Radbourn, who was unable to pitch one day because of a muscle cramp in his arm.