Doctors usually diagnose cystic fibrosis (CF) in infancy or early childhood, but some people may not receive a diagnosis until adulthood if their symptoms are mild or atypical.

CF is a hereditary condition that affects different cells that produce mucus, digestive juices, and sweat. These fluids are generally thin and slippery, but in people with CF, a gene mutation causes the secretions to become thick and sticky.

Instead of acting as a lubricant, the secretions plug tubes, ducts, and passageways, especially in the lungs and pancreas.

This article explores a late diagnosis of CF, including whether the time of diagnosis affects outcomes, treatment options, and symptoms.

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Doctors usually diagnose CF when people are very young, often within the first few months of life. According to the National Heart, Lung, and Blood Institute (NHLBI), most people receive a diagnosis by the time they are 2 years old.

The charity Cystic Fibrosis Canada defines a late diagnosis as one that occurs after 18 years old.

A late diagnosis may happen in cases where the symptoms are mild and do not present in a way that typically suggests CF.

People may downplay their symptoms when speaking with a doctor or receive an initial misdiagnosis, which can lead to a late CF diagnosis.

Diagnostic process

Screening and genetic testing can help doctors identify CF in infants and newborns. However, a late diagnosis may focus on a physical evaluation and tests.

Tests that healthcare professionals may use to diagnose CF include the following:

  • Sweat test: A sweat test measures the amount of salt in a person’s sweat. People with CF have much higher amounts of salt in their sweat than people without the condition.
  • Genetic testing: CF occurs due to mutations in the CFTR gene. Genetic testing can confirm the diagnosis and identify the specific mutations involved.
  • Lung function tests: These tests measure how well the lungs are working and can help in the diagnosis and management of CF.
  • Imaging: X-rays or CT scans of the chest can assess the extent of lung damage.
  • Sputum culture: Doctors may take a sample of a form of mucus called sputum to check for the presence of bacteria that commonly infect the lungs of people with CF.

Adults who receive a late CF diagnosis typically have milder symptoms and experience fewer hospitalizations than those who receive a childhood diagnosis.

However, since there is no cure for CF, a late diagnosis means treatment starts later. A person may experience complications that earlier treatment might have prevented or delayed.

Outlook and life expectancy

According to a 2022 article, the life expectancy for people with CF has been increasing steadily over the past few decades thanks to advances in treatment.

However, the article’s authors highlight that a late diagnosis is one factor that may contribute to worse outcomes in historically marginalized groups with CF.

The severity of the condition can vary widely, and some people might develop severe complications despite a late diagnosis. End stage lung disease is the most common cause of death among people with CF.

Learn more about cystic fibrosis and life expectancy.

The Centers for Disease Control and Prevention (CDC) lists the following common first signs of CF:

There is no cure for CF, so treatments work by helping manage the symptoms.

According to the NHLBI, doctors may prescribe or recommend the following treatment options:

  • antibiotics to treat infections
  • anti-inflammatory medicines
  • bronchodilators to make breathing easier
  • mucus-thinning medications
  • CFTR modulators to improve lung function
  • a liver or lung transplant

Having one or more of the symptoms of CF does not necessarily mean a person has the condition. However, people should speak with their doctor if they are concerned, particularly if they have a family history of CF.

A healthcare professional can find the cause of any concerning symptoms and help plan an appropriate course of treatment.

Although most people with CF receive a diagnosis as a child, doctors sometimes diagnose the condition later in life, particularly if a person has mild or atypical symptoms.

The outlook for people with CF is improving with time, but people should speak with a doctor to start treatment if they receive a late diagnosis.

Treatment options may include antibiotics, anti-inflammatories, and mucus-thinning drugs. In advanced cases, people may require organ transplants.