What lab tests are recommended for diagnosing mold exposure?

Laboratory Testing for Mold Exposure

There is no validated laboratory test to diagnose mold exposure in humans, and routine blood or urine testing for mycotoxins should be avoided. 1, 2

Evidence Against Routine Laboratory Testing

The American Academy of Pediatrics explicitly states that no validated method exists to test humans for toxigenic mold exposure, and no standardized serologic tests can reliably assess exposures to mold and other agents associated with damp indoor environments. 1, 2 While assays to detect mycotoxins and microbial volatile organic compounds in blood have been developed for research purposes, they have not been standardized for clinical use, and it remains unclear what levels are associated with health effects. 1, 2

Environmental mold testing is also not recommended as part of routine medical evaluation. 1, 2

Risk-Stratified Approach to Testing

The diagnostic approach depends entirely on the patient's immune status and clinical presentation:

For Immunocompromised Patients (High Priority)

Immediate cessation of mold exposure has absolute priority. 1, 3 If invasive fungal infection is suspected, the following tests are indicated:

• Radiological imaging: Chest CT scan (preferred over plain radiography) for suspected invasive pulmonary aspergillosis 4, 1
• Serum galactomannan antigen testing: Recommended for diagnosis of invasive aspergillosis in hematologic malignancy and hematopoietic stem cell transplant patients (strong recommendation; high-quality evidence) 4
• Serum (1→3)-β-D-glucan: Recommended for diagnosing invasive aspergillosis in high-risk patients, though not specific for Aspergillus 4
• Bronchoscopy with bronchoalveolar lavage (BAL): Recommended when clinically feasible, with BAL fluid sent for galactomannan testing, culture, and cytology 4
• Tissue culture and histopathology: The gold standard for proven invasive fungal disease, requiring adequate tissue specimens for simultaneous examination 4
• Immunological evaluation: Assessment of immune function status 1, 3

Important caveats: Galactomannan is NOT recommended for routine screening in solid organ transplant recipients, patients with chronic granulomatous disease, or patients receiving mold-active antifungal prophylaxis (blood screening only; BAL can still be used). 4

For Atopic/Allergic Patients

Skin prick testing and/or mold-specific IgE antibodies are the appropriate diagnostic tools for suspected IgE-mediated allergic responses to mold. 1, 5, 6 Studies show that specific IgE to mold mixture (mx1) is significantly more frequent in mold-exposed individuals (41%) compared to non-exposed (17%), particularly in exposed asthmatics (55%). 6

Mold-specific IgG testing is NOT useful and should be avoided, as it does not correlate with clinical disease. 2, 6

For Suspected Hypersensitivity Pneumonitis

High-resolution CT (HRCT) should be performed looking for centrilobular ground-glass nodules, mosaic attenuation, air-trapping, and three-density sign. 1, 2 However, imaging findings must be integrated with clinical findings and cannot be used in isolation. 2

Serum antigen-specific IgG or IgA testing should NOT be relied upon solely to confirm or rule out hypersensitivity pneumonitis diagnosis. 1, 2 Antigen-specific inhalation challenge testing and lymphocyte proliferation testing are also not recommended. 2

Critical Clinical Assessment Details

Focus your history on these specific elements:

• Exposure characteristics: Visible mold growth, water damage (leaks, floods, condensation), musty odors in home or workplace 1, 2
• Temporal relationship: Timing of symptoms relative to being in the suspected environment, improvement with avoidance 1, 2
• Immune status: Immunosuppression, chemotherapy, transplant status, HIV/AIDS, chronic granulomatous disease 1, 3
• Atopic history: Personal or family history of allergic rhinitis, asthma, atopic dermatitis 1, 5
• Symptom pattern: Rhinitis, cough, headache, respiratory symptoms, fatigue (most common presentations) 5

Physical examination findings may include pale nasal mucosa, pharyngeal "cobblestoning," and rhinorrhea in allergic presentations. 5

What NOT to Do

Avoid these common pitfalls:

• Do not order mycotoxin testing in blood or urine - these are not validated for clinical use 1, 2, 3
• Do not order environmental mold testing as part of medical evaluation - this is not indicated for clinical diagnosis 1, 2, 3
• Do not order mold-specific IgG antibodies - these do not predict disease 2, 6
• Do not rely solely on clinical improvement with antigen avoidance to confirm diagnosis 2
• Do not use PCR assays routinely - while promising, they lack standardization and should only be used carefully on a case-by-case basis in conjunction with other tests 4