Diagnosis and tests for asthma

Diagnosis and Tests for Asthma

Asthma is diagnosed by combining the story (variable symptoms, triggers, night worsening) with an objective test showing that airflow varies. No single test rules asthma in or out on its own - which is why a normal test on a good day does not end the conversation, and why treatment trials are sometimes part of diagnosis.

The Clinical History

The pattern matters most: wheeze, cough, tightness or breathlessness that comes in episodes, worsens at night and early morning, responds to triggers (dust, cold air, smoke, exercise, infections), and eases with a reliever inhaler. Family history of asthma, eczema or hay fever supports it, as does a personal history of allergies.

Spirometry with Reversibility - The Key Test

Spirometry measures how much and how fast you can blow out air. In asthma, the outflow (FEV1) is reduced relative to lung size - and crucially, it improves significantly after a reliever inhaler (reversibility) or varies between visits. This "variable airflow obstruction" is the objective signature of asthma. Spirometry is quick, painless and available at most hospitals and many clinics.

Other Tests That Help

• Peak flow monitoring: a hand-held tube measuring your fastest blow, recorded morning and evening over two weeks. Wide swings support asthma and later help track control.
• FeNO (exhaled nitric oxide): measures airway inflammation directly - high values support allergic-type asthma and predict steroid response.
• Allergy testing: skin-prick or blood IgE tests identify which allergens drive your asthma, guiding avoidance and biologic choices.
• Bronchial challenge tests: for suspected asthma with normal spirometry - the airway is provoked (with exercise or methacholine) to reveal its twitchiness.
• Chest X-ray or CT: not to diagnose asthma but to exclude look-alikes - COPD, TB, bronchiectasis, heart problems - especially in adults with new symptoms. In India, ruling out TB in persistent cough is standard care.

Why Diagnosis Before Treatment Matters

Inhalers started on a guess can be right, but they can also mask something else entirely - TB, vocal cord dysfunction, heart failure, reflux, or a foreign body in a child. Objective testing protects you twice: it confirms asthma when it is there and forces a rethink when it is not.

The Ayurvedic Perspective

Classical diagnosis of Shwasa roga was observational - recognising the wheeze, the relief on sitting upright, the pattern of triggers - Madhava Nidana, Chapter 12. It could distinguish asthma's pattern from other breathlessness remarkably well, but it could not measure the airway. Spirometry and FeNO now quantify what observation inferred, which is why modern diagnosis anchors on testing rather than on any single system's reading of symptoms.

Frequently Asked Questions

My spirometry was normal - does that rule out asthma? No. Between attacks, spirometry is often completely normal. Peak flow diaries, FeNO, challenge testing or a supervised treatment trial can still establish the diagnosis.

Do I need all these tests? Usually just spirometry with reversibility, plus allergy testing if an allergic driver is suspected. The rest are for unclear or severe cases.

Is a chest X-ray always needed? Not in a classic childhood presentation. In adults - especially smokers or anyone with persistent cough - imaging to exclude TB and other causes is routine and worthwhile.

Can blood tests diagnose asthma? No blood test diagnoses asthma itself; eosinophils and IgE support the allergic type and help choose biologics in severe disease.