Understanding quantiferon results

Overview

The QuantiFERON test is a blood test that checks if your immune system has been exposed to the bacteria that cause tuberculosis (TB). It measures how your white blood cells react to TB proteins. A positive result means you likely have a TB infection, but it doesn’t tell if the infection is active (causing symptoms) or latent (dormant in your body).

The QuantiFERON test is widely used in many countries for TB screening, especially in people at higher risk of infection. However, TB infection itself is less common in low-incidence countries like the United Kingdom, but it remains a significant health issue worldwide.

It is used for people who may have been exposed to TB, such as close contacts of someone with active TB, healthcare workers, people from countries where TB is common, and those with weakened immune systems (for example, from HIV, long-term steroid use, or certain medications).

Symptoms

Common symptoms

• Persistent cough lasting more than three weeks
• Coughing up blood or phlegm (sputum)
• Unexplained weight loss
• Night sweats
• Fever and chills
• Fatigue and weakness
• Chest pain or pain when breathing or coughing

Symptoms in children

• Poor growth or weight gain (failure to thrive)
• Persistent cough
• Fever that doesn’t go away
• Swollen lymph nodes (glands) in the neck
• Lethargy or being less active than usual

Symptoms in older adults

• Confusion or changes in mental state
• Loss of appetite
• Unexplained weight loss
• Persistent cough (may be less noticeable)
• Night sweats and fever (may be mild)

Causes

Main causes

• Infection with Mycobacterium tuberculosis bacteria, which is spread through the air when a person with active TB coughs, sneezes, or talks.

Risk factors

• Spending time with someone who has active TB (close contact)
• Living or working in crowded or poorly ventilated places (like prisons, homeless shelters, nursing homes)
• Having a weakened immune system (from HIV, diabetes, kidney disease, or medications like steroids or biologics)
• Traveling to or living in countries where TB is common
• Being a healthcare worker who may be exposed to TB patients

When to see a doctor

See a doctor urgently if:

• If you have a positive QuantiFERON test result, see a doctor soon for further evaluation (usually within a few weeks).
• If you have symptoms of active TB such as coughing up blood, unexplained weight loss, or night sweats, see a doctor urgently.

Book a routine appointment if:

• If you have been exposed to someone with TB and have no symptoms, get tested as part of routine screening.
• If you are starting a job in healthcare or moving into a care home, you may need a routine TB test.

Diagnosis

A diagnosis of TB infection begins with the QuantiFERON blood test. If the test is positive, your doctor will check for active TB disease by asking about symptoms, doing a physical exam, and ordering further tests such as a chest X-ray and a sample of your phlegm (sputum).

Tests that may be done

• QuantiFERON-TB Gold blood test
• Chest X-ray to look for changes in the lungs
• Sputum test (checking phlegm for TB bacteria under a microscope or by culture)
• Sometimes a CT scan or other imaging if needed
• If the infection is in other parts of the body, additional tests may be needed (like a biopsy)

What to expect at your appointment

Getting a blood test is quick and simple. After a positive result, you will likely be referred to a TB specialist clinic. They will explain the next steps gently. If you need a chest X-ray, it is painless and only takes a few minutes. Sputum tests require you to cough up phlegm into a cup. The whole process is meant to be as comfortable as possible.

Treatment

Treatment depends on whether you have latent TB infection (no symptoms) or active TB disease (symptoms). Latent TB is treated to prevent it from becoming active. Active TB requires a longer course of medicines to cure the infection and stop it from spreading to others. Treatment is highly effective when taken correctly.

Self-care at home

• Take all prescribed medicines exactly as directed, without missing doses.
• Get plenty of rest and eat a healthy diet to support your immune system.
• If you have active TB, cover your mouth and nose when coughing or sneezing, and avoid close contact with others until your doctor says you are no longer contagious.
• Keep all follow-up appointments so your doctor can monitor your progress.

Medical treatments

For latent TB, a course of preventive antibiotics is given for several months (usually 3 to 9 months depending on the regimen). For active TB, a combination of antibiotics is used for at least 6 months. Your doctor will choose the right plan based on your health and the type of TB. It is very important to complete the full course—stopping early can cause the infection to come back and become drug-resistant.

Living with this condition

If you have latent TB, you can lead a completely normal life – just remember to take your medication as prescribed. If you have active TB, you may need to stay home from work or school for a few weeks until you are no longer contagious. After that, you can safely return to daily activities.

Lifestyle tips

• Follow your treatment plan strictly without skipping doses.
• Avoid alcohol and tobacco, as they can affect your liver and make treatment less effective.
• Practice good hygiene, especially covering your mouth when you cough.
• If you are contagious, avoid spending time in crowded indoor spaces until your doctor says it is safe.

Diet and exercise

A balanced diet rich in fruits, vegetables, lean protein, and whole grains can help your body fight infection. Moderate exercise like walking is fine, but rest when you feel tired. Active TB can cause weight loss, so eating enough nutritious food is important.

Mental health and emotional wellbeing

A TB diagnosis can be stressful and may cause worry about your health or about infecting others. You might feel isolated if you have to stay away from people. These feelings are normal. It can help to talk to a counsellor or join a support group (ask your local health service for options).

Prevention

Yes, in many cases. The best way to prevent TB is to avoid close contact with people who have active TB disease, especially in poorly ventilated spaces. Good ventilation and wearing masks can reduce the risk. For people at high risk, testing and treating latent TB infection before it becomes active is a key prevention strategy.

Vaccines

The BCG vaccine is given in some countries to protect against severe forms of TB in children. It is not routinely used in the United Kingdom anymore for the general population, but may be recommended for babies in high-risk areas or for people with occupational exposure. The QuantiFERON test is not affected by BCG vaccination, unlike the skin test.

Screening programmes

Regular TB screening (with QuantiFERON or skin test) is recommended for people at high risk, such as healthcare workers, people with HIV, close contacts of TB patients, and people coming from countries where TB is common. Early detection of latent infection can prevent progression to active disease.

Complications

If left untreated

• Latent TB can progress to active TB disease, which can damage your lungs and other organs.
• Active TB can spread to other parts of the body (like the brain, spine, or kidneys), causing serious illness.
• Without proper treatment, TB can be life-threatening.
• Incomplete treatment can lead to drug-resistant TB, which is much harder to cure.

Long-term outlook

With complete and proper treatment, most people with TB infection make a full recovery. Even active TB is curable in over 95% of cases when medications are taken as prescribed. The key is to follow your doctor’s advice and finish all your medicine, even if you start feeling better.

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