Asthma differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Philip Marcus, M.D., M.P.H. [2] Associate Editor(s)-in-Chief:

Overview

Asthma must be clinically differentiated from other conditions that cause recurrent cough and wheezing such as viral bronchiolitis, chronic obstructive pulmonary disease, congestive heart failure, vocal cord dysfunction, ACE inhibitors use and allergic rhinitis.

Differentiating Asthma from other Diseases

• Asthma must be differentiated from other respiratory and cardiac diseases that can cause the same clinical manifestations like cough and dyspnea. These diseases include Bronchiolitis, COPD, pneumonia, congestive heart failure, diffuse idiopathic neuroendocrine cell hyperplasia, tuberculosis, pertussis, foreign body aspiration, pulmonary embolism and Harmann-Rich syndrome.

Diseases	Symptoms			Signs			Diagosis
	Fever	Cough	Chest pain	Wheezes	Crackles	Tachycardia	Lab tests	Imaging
Asthma	-	Dry/Productive	-	+	-	-	Lab tests to exclude other diseases Serum examination shows elevated level of eosinophils due to allergy	CT scan shows: Dilated bronchi Bronchial wall thickening Air trapping
Bronchiolitis	+/-	Dry	-	+	+	+/-	ELISA and immunoassays may be done in case of RSV infection Pulmonary function test to exclude other lung diseases	CT scan shows: Intense bronchiolar mural inflammation bronchial wall thickening Centrilobular nodules with tree-in-bud pattern
COPD	+	Productive	-	+	+	+	Spirometry: FEV1/FVC < 70% Arterial blood gases: hypoxemia and hypercapnia Sputum culture	EKG may show: P pulmonale right ventricular hypertrophy Narrow QRS CT scan is more sensitive in diagnosing COPD than X ray
Bacterial pneumonia	+	Productive	+	+	+	+/-	Diagnosis depends on presentation and physical examination Laboratory tests arterial blood gases may show hypoxia and acidosis Sputum culture	X ray is performed to detect: pleural effusion Inflitrates within the lungs. CT scan shows: Consolidation Ground glass appearance
Pulmonary embolism	+/-	Bloody	+	+	+	+	Arterial blood gases may show: Hypoxemia Hypocapnia Respiratory alkalosis Increased alveolar-arterial gradient D-dimer assay to rule out other diseases like DVT Hypercoagulability tests for patients with: Unprovoked venous thrombosis at an early age (< 40 years) Family history of VTE syndromes Routine blood tests are non specific	CT pulmonary angiography is the gold standard imaging to diagnose pulmonary embolism. CT may show: Acute:Centrally located thrombus occluding the vessel Chronic:Eccentric changes in the vessel wall, recanalization in the thrombous and arterial web EKG is not specific or sensitive in PE diagnosis but it may show: T wave inversion P pulmonale sinus tachycardia Chest X ray to exclude other differentials
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia	-	Dry	-	+	-	-	Pulmonary function test shows obstructive lung disease	CT scan may show: Multiple nodules Ground glass appearance Bronchiectasis.
Tuberculosis	+	Bloody	+	-	-	-	Sputum culture: Three successive positive culture for M. tuberculosis confirms the diagnosis Presence of acid fast bacilli in sputum smear indicates high extent tuberculosis	Chest X ray is an important diagnostic imaging procedure in TB diagnosis. X ray may show: Parenchymal infilration Hilar adenopathy Nodules Pleural effusion CT scan may show: Micronodules Cavitation Consolidation Interlobular septal thickening EKG may have abnormalities in case pleural effussion associated with TB.
Interstitial pneumonitis (Hamman - Rich syndrome)	+	Productive	-	-	+	-	Arterial blood gases may show: hypoxemia PaO2/FiO2 less than 200 mmHg indicating acute respiratory distress syndrome Other lab tests are done to exclude other diseases	Chest X ray may show: Bilateral airway opacification CT scan may show Ground glass appearance. Bronchoscopy to exclude other causes such as: alveolar hemorrhage lymphoma. Lung biopsy is done: In unclear cases; to confirm acute interstitial pneumonitis Exclude other causes of ARDS
Foreign body aspiration	+	Bloody	+	+	-	-	Lab tests to evaluate the ventilation function	Chest X ray shows: Hyperinflation Mediastinal shift Aatelectasis
Pertussis	+	Dry		-	-	-	Nasopharyngeal swab for PCR testing Sputum culture Serology to detect pertussis toxin	No remarkable imaging findings
Congestive heart failure	-	Dry/Productive	+ while walking	-	-	+	Routine lab tests to identify the cause of the heart failure: Renal function tests including urinalysis and electrolytes Complete blood count Thyroid studies in patients being treated with concomitant therapy such as amiodarone Biomarkers: BNP or NT-proBNP Cardiac Troponin T or I Carbohydrate Antigen 125	EKG to detect underlying cause Chest x ray shows cardiomegaly Echocardiography is done: To determine stroke volume To assess type of heart failure

• Although, many cases of recurrent cough and wheezing in children and adults are due to asthma, other conditions are often misdiagnosed as asthma.

Adults

• Chronic obstructive pulmonary disease (COPD)
• Hyperventilation syndrome and panic attacks
• Congestive heart failure
• Pulmonary embolism
• Laryngeal dysfunction
• Pulmonary aspiration
• Mechanical obstruction of the airways (benign and malignant tumors)
• Pulmonary infiltration with eosinophilia
• Diffuse parenchymal lung diseases
• Cough, secondary to drugs (ACE inhibitors)
• Vocal cord dysfunction
• Pharyngitis

Infants & Children

Upper airway diseases

• Allergic rhinitis and sinusitis

Obstructions involving large airways

• Foreign body in trachea or bronchus
• Vocal cord dysfunction
• Vascular rings or laryngeal webs
• Laryngotracheomalacia, tracheal stenosis, or bronchostenosis
• Enlarged lymph nodes or tumor

Obstructions involving small airways

• Viral bronchiolitis or obliterative bronchiolitis
• Cystic fibrosis
• Bronchopulmonary dysplasia

Other causes

• Congenital heart diseases
• Recurrent cough not due to asthma
• Aspiration from swallowing mechanism
• Gastroesophageal reflux