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PubMed This is a summary of 15 peer-reviewed journal articles Updated
Pulmonology

The Underlying Causes: Why Getting to the Root Matters

At a Glance

Finding the exact root cause of bronchiectasis is crucial because it directly influences your treatment options. Doctors use specialized blood, genetic, and breathing tests to identify underlying issues like immune deficiencies, Primary Ciliary Dyskinesia, or past infections to provide precise care.

A diagnosis of bronchiectasis is often just the beginning of the journey. While the CT scan shows what is happening—your airways have widened and scarred—it doesn’t explain why. Finding the root cause of your bronchiectasis is one of the most important steps in your care because the “why” often dictates the “how” of your treatment [1][2].

CF vs. Non-CF Bronchiectasis

The first big distinction doctors make is between Cystic Fibrosis (CF) and non-CF bronchiectasis.

  • Cystic Fibrosis: This is a specific genetic condition caused by mutations in the CFTR gene [3]. It affects how salt and water move in and out of cells, creating exceptionally thick, sticky mucus throughout the body.
  • Non-CF Bronchiectasis: This is an “umbrella term” for airway damage caused by a wide variety of other factors [4].

It is important to know that treatments that work for CF (like certain inhaled medications) may not work for non-CF bronchiectasis and can sometimes even be unhelpful or harmful [5].

Common Underlying Causes (Etiologies)

In many cases, a thorough investigation can uncover a specific cause, which allows your doctor to move from general symptom management to precision medicine [6].

  • Post-Infectious: Many people develop bronchiectasis after a severe respiratory event earlier in life, such as whooping cough (pertussis), tuberculosis, or a particularly aggressive bout of pneumonia [7]. The infection causes the initial damage, and the “vicious cycle” takes over from there.
  • Immunodeficiencies: Sometimes the root cause is an immune system that isn’t producing enough antibodies to fight off common bacteria [8]. Conditions like Common Variable Immunodeficiency (CVID) can be treated with immunoglobulin replacement therapy, which may prevent further lung damage [9][10].
  • Primary Ciliary Dyskinesia (PCD): This is a genetic condition where the tiny hairs in your lungs (cilia) don’t beat correctly [11]. Because the “brooms” of the lung are broken, mucus and bacteria sit in the airways, leading to damage.
  • Alpha-1 Antitrypsin Deficiency (AATD): This is a genetic lack of a protective protein in the blood. While often linked to emphysema, it is also a recognized cause of bronchiectasis [12][13].

Why Specialized Testing Matters

Your care team may recommend a series of tests to “rule in” or “rule out” these causes. This might include:

  1. Blood Work: To check your immunoglobulin levels and see how well your body responds to vaccines [9].
  2. Genetic Testing: Specifically for Alpha-1 or CFTR mutations [13].
  3. Nasal Nitric Oxide: A simple breathing test used to screen for PCD [11].
  4. Aspergillus Testing: To check for Allergic Bronchopulmonary Aspergillosis (ABPA), an allergic reaction to a common fungus that can cause significant airway inflammation [14].

Even if your bronchiectasis is eventually labeled “idiopathic” (meaning the cause remains unknown), the process of testing ensures that you aren’t missing out on a specific treatment that could protect your lungs for the future [15].

Next Step: Learn how to read your own reports in Understanding Your HRCT Scan and Sputum Reports.

Common questions in this guide

What is the difference between CF and non-CF bronchiectasis?
Cystic Fibrosis (CF) bronchiectasis is caused by a specific genetic mutation in the CFTR gene that creates abnormally thick mucus. Non-CF bronchiectasis is an umbrella term for airway damage caused by other factors, such as past infections, immune disorders, or different genetic conditions.
Why do I need genetic testing if I have bronchiectasis?
Genetic testing helps doctors identify underlying conditions like Alpha-1 Antitrypsin Deficiency or mild Cystic Fibrosis mutations. Discovering the exact cause allows your care team to move from general symptom management to personalized, precision medicine tailored to your body.
Can childhood infections cause bronchiectasis later in life?
Yes, severe respiratory infections early in life, such as whooping cough, tuberculosis, or severe pneumonia, can cause initial airway damage. This damage can start a cycle of chronic inflammation and recurrent infection that leads to bronchiectasis years later.
What is Primary Ciliary Dyskinesia (PCD)?
Primary Ciliary Dyskinesia is a genetic condition where the tiny hair-like structures in your lungs, called cilia, do not beat correctly. Without working cilia to sweep away debris, mucus and bacteria build up in the airways and cause permanent damage.
How do doctors test for immune system issues related to bronchiectasis?
Your doctor can perform blood tests to check your immunoglobulin levels and evaluate how well your body responds to vaccines. If your immune system is not producing enough antibodies, treatments like immunoglobulin replacement therapy may help prevent further lung damage.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Have I been tested for Alpha-1 Antitrypsin deficiency, even if I don't have signs of emphysema?
  2. 2.Should we perform a 'nasal nitric oxide' test to screen for Primary Ciliary Dyskinesia (PCD)?
  3. 3.Are my immunoglobulin levels (IgG, IgA, IgM) normal, and do I need to see an immunologist to check my vaccine responses?
  4. 4.Is it possible that an old infection from my childhood is the reason for my bronchiectasis now?
  5. 5.Could my symptoms be related to Allergic Bronchopulmonary Aspergillosis (ABPA), and have I been tested for Aspergillus sensitivity?

Questions For You

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References

References (15)
  1. 1

    Non-CF bronchiectasis: Orphan disease no longer.

    Imam JS, Duarte AG

    Respiratory medicine 2020; (166()):105940 doi:10.1016/j.rmed.2020.105940.

    PMID: 32250872
  2. 2

    [Management of adult bronchiectasis - Consensus-based Guidelines for the German Respiratory Society (DGP) e. V. (AWMF registration number 020-030)].

    Ringshausen FC, Baumann I, de Roux A, et al.

    Pneumologie (Stuttgart, Germany) 2024; (78(11)):833-899 doi:10.1055/a-2311-9450.

    PMID: 39515342
  3. 3

    Genetic background of pulmonary (vascular) diseases - how much is written in the codes?

    Eichstaedt CA, Haas SO, Shaukat M, Grünig E

    Current opinion in pulmonary medicine 2024; (30(5)):429-436 doi:10.1097/MCP.0000000000001090.

    PMID: 38913028
  4. 4

    Noncystic Fibrosis Bronchiectasis: Evaluation of an Extensive Diagnostic Protocol in Determining Pediatric Lung Disease Etiology.

    Beckeringh NI, Rutjes NW, van Schuppen J, Kuijpers TW

    Pediatric allergy, immunology, and pulmonology 2019; (32(4)):155-162 doi:10.1089/ped.2019.1030.

    PMID: 32140286
  5. 5

    Proteomics and Metabolomics for Cystic Fibrosis Research.

    Liessi N, Pedemonte N, Armirotti A, Braccia C

    International journal of molecular sciences 2020; (21(15)) doi:10.3390/ijms21155439.

    PMID: 32751630
  6. 6

    Inflammatory Phenotypes of Bronchiectasis.

    Koukaki E, Papaiakovou G, Klironomou A, et al.

    Journal of personalized medicine 2025; (15(10)) doi:10.3390/jpm15100499.

    PMID: 41149860
  7. 7

    Antibody deficiencies with normal IgG in adults with Non-cystic fibrosis bronchiectasis or recurrent pneumonia: Cross-sectional study.

    Zea-Vera AF, Chacón MA, Parra B

    Colombia medica (Cali, Colombia) 2022; (53(2)):e2014832 doi:10.25100/cm.v53i2.4832.

    PMID: 36415694
  8. 8

    Non-cystic fibrosis bronchiectasis in pediatrics: A cohort profile of patients with inborn errors of immunity at a referral center in Cali, Colombia

    Murillo A, Marín D, Triviño J, et al.

    Biomedica : revista del Instituto Nacional de Salud 2024; (44(Sp. 2)):131-139 doi:10.7705/biomedica.7558.

    PMID: 39836842
  9. 9

    Infections, autoimmunity and immunodeficiencies are the leading etiologies of non-cystic fibrosis bronchiectasis in adults from the southwest of Colombia.

    Zea-Vera AF, Rodríguez CA, Giraldo S, et al.

    Biomedica : revista del Instituto Nacional de Salud 2024; (44(Sp. 2)):80-93 doi:10.7705/biomedica.7500.

    PMID: 39836848
  10. 10

    Bronchiectasis is associated with delayed diagnosis and adverse outcomes in the New Zealand Common Variable Immunodeficiency Disorders cohort study.

    Ameratunga R, Jordan A, Cavadino A, et al.

    Clinical and experimental immunology 2021; (204(3)):352-360 doi:10.1111/cei.13595.

    PMID: 33755987
  11. 11

    Primary Ciliary Dyskinesia in Adult Bronchiectasis: Data from the German Bronchiectasis Registry PROGNOSIS.

    Ewen R, Pink I, Sutharsan S, et al.

    Chest 2024; (166(5)):938-950 doi:10.1016/j.chest.2024.05.023.

    PMID: 38880279
  12. 12

    Alpha-1 antitrypsin deficiency in bronchiectasis: Evidence for an overlooked entity beyond COPD: A retrospective observational study.

    Özdemir L, Pazarli AC, Gegin S, et al.

    Medicine 2026; (105(4)):e47298 doi:10.1097/MD.0000000000047298.

    PMID: 41578478
  13. 13

    Prevalence of SERPINA1 mutations in a bronchiectasis cohort: implications of extended screening for alpha-1 antitrypsin deficiency.

    Sokoloski CS, Canan MGM, Leitão CA, Storrer KM

    Jornal brasileiro de pneumologia : publicacao oficial da Sociedade Brasileira de Pneumologia e Tisilogia 2025; (51(5)):e20250181 doi:10.36416/1806-3756/e20250181.

    PMID: 41370566
  14. 14

    Aspergillus-Associated Endophenotypes in Bronchiectasis.

    Jaggi TK, Ter SK, Mac Aogáin M, Chotirmall SH

    Seminars in respiratory and critical care medicine 2021; (42(4)):556-566 doi:10.1055/s-0041-1730947.

    PMID: 34261180
  15. 15

    Heterogeneity in non-cystic fibrosis bronchiectasis: insights from ASPEN trial participants.

    Ross MH, Jia S

    ERJ open research 2024; (10(4)) doi:10.1183/23120541.00372-2024.

    PMID: 39081500

This page provides general information about the underlying causes of bronchiectasis and is for educational purposes only. Always consult your pulmonologist to determine the appropriate diagnostic testing for your specific condition.

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