What are the diagnostic methods for Primary Ciliary Dyskinesia (PCD)?

From the Guidelines

Primary ciliary dyskinesia (PCD) diagnosis should be based on a combination of clinical evaluation, screening tests, and confirmatory diagnostic procedures, including nasal nitric oxide measurement, transmission electron microscopy, high-speed video microscopy, immunofluorescence testing, and genetic testing, as recommended by the most recent guidelines 1. The diagnosis of PCD begins with a thorough clinical assessment looking for characteristic symptoms such as chronic sinusitis, recurrent respiratory infections, bronchiectasis, and situs inversus (in about 50% of cases). Initial screening often includes nasal nitric oxide measurement, which is typically low in PCD patients due to reduced production in the sinuses and airways. Some key points to consider in the diagnosis of PCD include:

• The use of transmission electron microscopy to identify ultrastructural defects in the cilia, although this method has limitations, such as nonspecific ciliary changes that can be induced by environmental pollutants or infection 1.
• The importance of high-speed video microscopy to assess ciliary beat pattern and frequency, as well as immunofluorescence testing to detect missing ciliary proteins.
• The increasing importance of genetic testing, as over 40 genes associated with PCD have been identified, and a definitive diagnosis typically requires at least two positive diagnostic tests or identification of biallelic mutations in a known PCD gene 1. A definitive diagnosis of PCD is crucial, as it allows for prompt initiation of airway clearance techniques and aggressive management of respiratory infections to prevent progressive lung damage, and the most recent guidelines from the American Thoracic Society provide a comprehensive approach to the diagnosis of PCD 1.

From the Research

Diagnosis of Primary Ciliary Dyskinesia

The diagnosis of primary ciliary dyskinesia (PCD) involves a combination of tests, including:

• Nasal nitric oxide (nNO) measurements, which have been shown to be a sensitive and specific test for PCD 2
• High-speed videomicroscopy analysis (HSVMA) to assess ciliary beat frequency and pattern 3
• Immunofluorescent staining to examine ciliary structure 3
• Axonemal ultrastructure analysis via transmission electron microscopy (TEM) to assess ciliary morphology and orientation 4, 3
• Genetic testing to identify mutations in genes associated with PCD 3

Diagnostic Tests

The following tests may be used to diagnose PCD:

• Saccharin test in patients older than 10 years 4
• Ciliary beat frequency and pattern on light microscopy 4
• Electron microscopy to assess ciliary morphology and orientation 4, 3
• Nasal brushing for phase-contrast microscopy study of ciliary morphology and activity 5
• Measurement of nasal nitric oxide level 5, 6, 2

Diagnostic Approach

The diagnostic approach for PCD typically involves a combination of clinical evaluation, history-taking, and diagnostic tests. The following steps may be taken:

• Clinical evaluation to identify symptoms and signs of PCD, such as neonatal respiratory distress, recurrent lower respiratory tract infections, and chronic rhinosinusitis 4, 3
• History-taking to gather information on the patient's medical history, family history, and symptoms 5
• Measurement of nasal nitric oxide level as a screening test for PCD 6, 2
• Referral for further diagnostic testing, such as HSVMA, immunofluorescent staining, and genetic testing, if PCD is suspected 3, 6