Prevalence rate of tuberculosis or TB, is around 2.2 cases for every hundred thousand of the population. Accounting for more than 7000 cases, the number though lesser when compared with prevalence rates in other nations, needs to be managed and controlled effectively. This involves testing and screening of individuals. One of the commonly used tests to diagnose TB is tuberculin purified protein derivative skin test, that is typically used to check individuals classified as high risk.  As the test involves an injection, there is a possibility of undesirable effects. Subsequent sections offer in-depth information about the test and possible tb test side effects.

Symptoms of TB

One of the reasons that make TB difficult to determine initially, is the lack of symptoms at the initial stage in certain individuals. Though the patient may have been infected with the bacteria, the condition develops only when the bacteria is fully active.  Symptoms begin to appear or be experienced only at this stage. Individuals need to quickly look for diagnostics to check for TB on observing any of the following symptoms. For instance, sudden weight loss not attributed to any other health condition is a symptom.  Patients are known to exhibit an unusual disinterest in food, and may end up feeling tired all the time. There is the possibility of the patient experiencing sweating in the nights, and may also have fever.

Cough is one of the more commonly known symptoms of TB, and patients with persistent cough are to seek treatment at the earliest, as there is a likelihood of this progressing to adverse conditions. There is the likelihood of blood being coughed up, and patients may require intensive treatment in such instances.

Overview of the test

Tuberculosis, or TB as it is commonly known is an infection caused by Mycobacterium tuberculosis bacteria. The test for TB is performed by an injection on the skin with tuberculin PPD that is available as a solution. The site of injection will end up creating a small wheal, which is essentially a raised-up portion on the skin. After 48 or 72 hours of administering the injection, the doctor checks the site to assess the results. During this inspection, the doctor measures the diameter of the raised bump, and depending on the size of the bump will determine if the individual has TB.

Wheal size with diameter smaller than 5 mm is considered as indicative of a negative result. Wheal sizes larger than 5 mm are considered as positive results. Depending on the size, the doctor further assesses the patient by carefully looking for possibilities of the infection. There are various parameters that are considered during this evaluation and certain factors are known to be considered as putting the individual at high risk of TB infection.

For instance, if the individual has come into close contact with another TB patient, the risk is high. Similarly, healthcare workers who may have been exposed to TB patients are also at high risk. Other factors that are weighed include past TB infections, and patients who are HIV positive. Patients who have undergone organ transplant procedures or patients who are on drugs belonging to the category of immunosuppressants are also at high risk. Addicts who share hypodermic needles are also at high risk of contracting the infection.

Whenever the size of the wheal is huge, the result is regarded as positive confirmed, without the need to check for other factors.

Precautions to be followed before taking the test

It is necessary to follow certain precautions before taking the test to prevent the possibilities of undesirable effects. For instance, individuals with a history of allergies are to inform the same to the treating specialist as this may lead to strong and severe side effects. This includes any history of allergies to animal dander, preservatives specific food products or dyes.

Other tests used to diagnose the condition

There are other tests that help to confirm TB in patients with a greater level of accuracy. X-rays and CT scans help to determine the condition, as the X-rays and CT scan reports of patients with TB are distinct with white spots that indicate problems in the lungs. Other tests include a sputum test that narrow down the TB bacteria, and helps to determine the right line of treatment for best outcomes. Blood tests are the other types of tests conducted for patients with a history of adverse reactions to the skin test. Known as the Interferon Gamma Release Assay test, this is recommended only for certain patients and is decided by the doctor.

How to read/interpret test results

There are slight variations in the test results and it helps to be aware of the same. Positive results indicates that the patient has TB, and the skin test has caused the growth of a wheal large enough to confirm presence of TB. Negative results indicates that the patient does not have TB, and the symptoms that were assumed to be of TB are attributed to other conditions that need to be ascertained.

Other types of results include false positive and false negative. The former refers to test results appearing to be positive, despite not having TB. This is mainly witnessed in patients who have been vaccinated against TB and who undergo tests. The reason for such results is bacterial infections that are similar to that of TB. False negative, refers to results that appear to show the patient as free from TB, though the patient is actually infected with TB. Patients with exposure to pathogens or patients with weak immunity are likely to end up with false negative results. It is necessary for patients who have had TB in the past, to undergo the right kind of tests for greater accuracy in determining TB.

Possible tb test side effects – drug interactions

There is a possibility of drug interactions from TB tests or medication. This is because of the mechanism of action of drugs interacting with the solution used in the tests or medication. Depending on the condition, it may be necessary to stop either of the medications to prevent the interaction. This will be decided by the criticality of the condition and the outcomes of the medications. If a condition is life endangering in nature, medications for the condition cannot be stopped and it may be necessary to stop the other conflicting medication.

However, in certain instances, both the conditions and medications may be equally important and it may be impossible to stop either. In such situations, the dosage may be altered, or the schedule may be staggered to mitigate the effects of the interaction. Patients are to explicitly intimate the treating specialists about all medications in use. This includes prescription medications, OTC formulations, supplements, herbal products, alternative medicine etc.

General precautions with TB medications and tests

To prevent the possibility of tb test side effects or side effects from medications, it is necessary to follow various precautions. This includes the need to abstain from alcohol or tobacco products, as this may have an impact on the outcomes of medications and tests. As TB affects the lungs, it is absolutely necessary to give up smoking, as the effects of the medication and treatment may be negated with aggravation of the lungs from smoking. Certain food products also affect the outcomes of medications, and it is essential to seek medical advice about the kind of food that is permitted and not permitted. It is also important to diligently follow the instructions about intake of medications before food or after food.

Impact of other conditions on outcome of test

Certain conditions may have an impact on the outcome of het test. It is necessary to intimate the doctors about the conditions, so as to help interpret results accordingly. For instance, patients with eczema or other skin conditions including skin burns on the forearms are likely to end up with less than accurate results.

As mentioned earlier, patients with a history of allergies are to avoid the medication as this may adversely affect the patient. This is especially true in the case of patients with anaphylaxis. This allergic reaction is a serious condition and is life endangering in nature. There are clear and distinct symptoms that indicate this condition and patients or caregivers are to carefully observe and report such symptoms. It is necessary for the patient to be rushed to a suitable healthcare facility in the event of certain symptoms being observed. For instance, outbreak of rashes, or difficulty in breathing, or severe itching are all indications of allergic reactions.  Similarly, patients experiencing any difficulty in swallowing food or liquid are also to seek medical attention at the earliest. Swelling in the face, or the hands are not to be disregarded as trivial but need medical intervention at the earliest, before it turns uncontrollable.

Commonly reported side effects of the test

Patients are known to faint after the test, and this is not a cause for concern. This is purely temporary in nature and the patient will recover quickly to continue routines. There are tell tale symptoms that may accompany or precede fainting after the test. This includes a sudden lightheaded feeling, or possible seizure like episodes. Patients may experience an unexplained and unusual feeling of weakness in the muscles, and this needs to be regarded as a precursor to fainting.

Patients may experience bleeding at the site of injection and this may last for as long as there days after the injection has been administered. The site of injection may turn dark in color, and may have a deep purplish appearance. Bleeding is another possible outcome at the site of injection. Additionally, patients may experience some formation of crusts and blisters at the site of injection, while some are known to experience formation of scabs. Breathing is likely to be labored for a short period, and heartbeat rate may also change to a pacy rate. There could be other visible effects such as swelling on the face, similar to that of hives, and this could also be experienced in the hands, the feet, or other sex organs, apart from the throat. Most of the side effects are known to resolve naturally and will not require medical attention or intervention. Certain undesirable outcomes require immediate attention, especially allergic reactions or when there is an effect on breathing and heart-beat.

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