Table 1 |.

Differential diagnosis

Diagnosis	Signs and symptoms	Recommended test or evaluation
Alcohol and other substance use disorders	Anxiety, tremor, sweating, palpitations during intoxication (for example, with methamphetamine), withdrawal (for example, from alcohol) and panic attacks (with marijuana use)	Clinical interview to determine whether the patient has a history of substance abuse or acute intoxication Urine or plasma drug screening might be indicated, for example, when history alone might be unreliable, such as when a patient has a prior history of misuse or abuse of drugs or alcohol
Caffeine and other stimulant use (for example, ephedrine and pseudoephedrine)	Panic attacks or chronic anxiety, insomnia, palpitations and tremor*	Clinical interview to determine whether the patient has a history of caffeine or other stimulant (for example, over-the-counter cold remedies) use or increase in habitual dose
Hyperthyroidism	Heat intolerance, weight loss, tremor, palpitations, ocular signs (with Graves disease, an autoimmune cause of hyperthyroidism), panic attacks or persistent anxiety	Laboratory measurement of plasma thyroid-stimulating hormone; routine testing is indicated because thyroid disorders are relatively common
Adrenal medullary tumours (pheochromocytoma)	Diaphoresis, headaches, palpitations, hypertension and panic attacks	Plasma metadrenaline testing or 24-hour urinary collection for catecholamines and metadrenalines Routine testing is not indicated owing to the rarity of these disorders, but testing should be considered in second-tier evaluations
Cardiac disease (for example, angina, myocardial infarction or arrhythmia)	Palpitations or chest pain	Electrocardiogram Further evaluations can include plasma troponin levels if the patient presents with acute cardiac-like pain, Holter monitoring and cardiology consultation
Mitral valve prolapse	Palpitations	Echocardiogram Mitral valve prolapse is incidental and should not influence anxiety treatment planning
Respiratory disease (such as asthma or chronic obstructive pulmonary disease)	Shortness of breath and ‘air hunger’ (might be symptoms of panic attacks)‡	Clinical evaluation and pulmonary function testing as needed
Epilepsy (complex partial seizures)	Anxiety and other emotional symptoms in addition to changes in awareness§	Clinical evaluation Consider in a second tier of medical evaluation if aetiology of symptoms remains unclear after initial evaluation and/or symptoms are refractory to standard anxiety treatments

^*Patients prone to anxiety may be more sensitive to caffeine and other stimulants.

^‡Asthma or chronic obstructive pulmonary disease may co-occur with an anxiety disorder.

^§Anxiety and other emotional symptoms may occur as part of the aura or as the initial manifestation of seizures.