Best FeNO Test in Hyderabad at Dr. Raju's Allergy Centre & Multispeciality Hospital

What is a FeNO Test?

A FeNO test (Fractional Exhaled Nitric Oxide test) is a simple, non-invasive breathing test that measures the level of nitric oxide in your breath. Nitric oxide is a gas produced by cells in the lungs, and elevated levels indicate airway inflammation, specifically the type of inflammation associated with asthma.

When airways become inflamed, the cells lining the bronchial tubes produce increased amounts of nitric oxide. By measuring this gas in exhaled breath, doctors can assess the degree of airway inflammation, confirm an asthma diagnosis, predict response to treatment, and monitor disease control over time.

At Dr. Raju's Allergy Centre, we utilise advanced FeNO testing technology to provide objective, quantitative measurements of airway inflammation. This test complements traditional lung function tests like spirometry, offering a complete picture of your respiratory health.

Why is FeNO Testing Important?

FeNO testing has revolutionised asthma management by providing an objective measure of airway inflammation. Unlike other tests that assess lung function (how well air moves), FeNO assesses the underlying inflammation that drives asthma symptoms.

Key Benefits of FeNO Testing

• Objective Measurement: Numerical value for airway inflammation
• Early Detection: Identifies inflammation before symptoms
• Accurate Diagnosis: Helps distinguish asthma from similar conditions
• Treatment Guidance: Predicts response to inhaled corticosteroids
• Monitoring Tool: Tracks inflammation and treatment effectiveness
• Medication Optimisation: Helps determine right dose of anti-inflammatory medications
• Predicting Exacerbations: Rising FeNO may indicate impending flare-ups
• Reducing Over-treatment: Identifies patients who may not need high-dose steroids

How Does FeNO Testing Work?

The Science: Nitric oxide is produced by epithelial cells lining the airways. The enzyme inducible nitric oxide synthase (iNOS) produces nitric oxide in response to inflammation, particularly eosinophilic inflammation in allergic asthma. When asthma is well-controlled, FeNO levels typically decrease.

The Procedure: You are seated; take a deep breath through a filter; exhale steadily into a mouthpiece at a specific flow rate (typically 50 mL/second) for 10 seconds; the analyser measures nitric oxide; results within minutes.

What Makes FeNO Unique: Non-invasive (no needles, no radiation); patient-friendly (adults and children 4–5 years); quick (5–10 minutes); reproducible; immediate results.

Interpreting FeNO Results

FeNO levels are measured in parts per billion (ppb). Interpretation depends on age, symptoms, and clinical context.

Adult Reference Ranges

Child Reference Ranges (Age < 12 years)

Elevated FeNO: Active eosinophilic inflammation; likely steroid responsiveness; poorly controlled asthma; allergic phenotype; possible non-adherence or poor inhaler technique; ongoing allergen exposure.

Normal FeNO: Absence of eosinophilic inflammation; non-eosinophilic phenotype; well-controlled asthma; good adherence; or alternative diagnosis.

Clinical Applications of FeNO Testing

1. Diagnosing Asthma: Confirms diagnosis when spirometry is normal but symptoms suggest asthma; useful when patients cannot perform spirometry; differentiates from vocal cord dysfunction, chronic cough, COPD.

2. Predicting Response to Inhaled Corticosteroids: High FeNO (>50 ppb): excellent likelihood of response; Intermediate (25–50 ppb): trial warranted; Low (<25 ppb): unlikely to respond; alternative treatments may be better.

3. Monitoring Asthma Control: Rising FeNO: worsening control or impending exacerbation; stable/decreasing: good control; persistently high despite steroids: adherence or technique issues.

4. Assessing Treatment Adherence: Elevated FeNO despite prescribed steroids suggests non-adherence; normalisation after directly observed therapy confirms it.

5. Phenotyping Asthma: Identifies eosinophilic phenotype—responds well to inhaled steroids; may benefit from biologic therapies.

6. Predicting Exacerbations: Rising FeNO may precede attacks by weeks, allowing early intervention.

How to Prepare for a FeNO Test

Before the Test (3 hours): Avoid foods high in nitrates—leafy greens (spinach, lettuce, kale), beetroot, cured meats (bacon, ham, salami), processed foods with nitrates/nitrites.

1 Hour Before: No smoking, alcohol, caffeine, or strenuous exercise. Continue regular medications unless instructed otherwise.

What to Bring: Doctor's referral, insurance information, medication list, previous FeNO results, questions for the doctor.

What to Expect During the Test

Seated comfortably; technician explains and demonstrates; deep breath through filter; steady exhalation into mouthpiece for ~10 seconds; device provides feedback for correct flow; 2–3 attempts for reproducibility. Appointment: 10–15 minutes. You may feel mild lightheadedness; no pain. Children tolerate it well with coaching.

Who Should Have a FeNO Test?

Diagnostic: Suspected asthma when diagnosis is uncertain; chronic cough; symptoms with normal spirometry; differentiating asthma from other conditions.

Monitoring: Confirmed asthma for control assessment; on inhaled corticosteroids; frequent exacerbations; poor response to medications; assessing adherence; pre-school wheezing.

Factors Affecting FeNO Levels

Increase FeNO: Eosinophilic inflammation, allergic asthma, atopy, allergen exposure, viral infections, uncontrolled asthma, non-adherence, eosinophilic bronchitis.

Decrease FeNO: Inhaled or systemic corticosteroids, smoking, cystic fibrosis, bronchiectasis, primary ciliary dyskinesia, pulmonary hypertension, acute alcohol ingestion.

FeNO vs. Other Asthma Tests

Why Choose Dr. Raju's Allergy Centre for FeNO Testing?

• Specialised Expertise: Deep understanding of airway inflammation in asthma
• Advanced Technology: State-of-the-art FeNO analysers
• Child-Friendly Approach: Testing children 4–5 years and older
• Integrated Care: FeNO combined with spirometry, allergy testing, clinical evaluation
• Personalised Plans: Results inform medication and dosing
• Monitoring: Serial testing to optimise therapy
• Clear Communication: Results explained with practical guidance

FeNO Testing in Children

Advantages: Non-invasive, painless; minimal cooperation (4–5 years); helps diagnose when symptoms are non-specific; predicts steroid response; monitors adherence; identifies those who may outgrow asthma.

Indications: Chronic cough, wheezing, exercise-induced symptoms, family history of asthma/allergy, poorly controlled "asthma," differentiating viral wheeze from allergic asthma.

Frequently Asked Questions

Is it painful? No. You breathe into a mouthpiece while the device measures nitric oxide.

How long? 10 seconds per attempt; 2–3 attempts; entire appointment 10–15 minutes.

Referral? Yes. Bring prescription or referral.

Can I eat? Avoid nitrate-rich foods (leafy greens, beetroot, cured meats) 3 hours before.

Medications? Continue unless instructed otherwise. Inform technician of all medications.

How often? Initial: once; poorly controlled: every 2–3 months; stable: every 6–12 months.

Diagnose all asthma types? FeNO detects eosinophilic inflammation (most allergic asthma). Non-eosinophilic asthma may have normal FeNO; used with other tests.

Normal FeNO but asthma symptoms? Some phenotypes (neutrophilic, paucigranulocytic) don't elevate FeNO. Doctor will consider context.

Insurance? Most plans cover medically necessary FeNO testing.

Conditions Where FeNO Testing is Helpful

• Allergic asthma, eosinophilic asthma, chronic cough, cough-variant asthma
• Occupational asthma, allergic rhinitis (lower airway involvement)
• Assessing treatment response, predicting exacerbations

After Your FeNO Test: Next Steps

Dr. Raju CH will: review results; correlate with symptoms; integrate with spirometry and allergy testing; confirm or refine diagnosis; adjust treatment (high FeNO: start/increase inhaled steroids; low FeNO with symptoms: consider alternatives; rising FeNO: address adherence/technique or step up); develop management plan; schedule follow-up.

"FeNO testing has transformed asthma management by bringing objectivity to the assessment of airway inflammation. This simple, non-invasive test helps us identify the right patients for anti-inflammatory therapy, optimise medication dosing, and monitor treatment effectiveness – all with the goal of achieving better asthma control and improving quality of life."