Definition & diagnostic considerations

Anxiety disorder due to another medical condition is diagnosed when prominent anxiety symptoms are the direct physiological consequence of a medical condition. Clinicians must document temporal relationship, plausibility of the medical cause, and exclude primary anxiety disorders or substance/medication effects.

Common medical causes

• Endocrine: hyperthyroidism, pheochromocytoma, Cushing’s syndrome, hypoglycaemia.
• Cardiorespiratory: arrhythmias (SVT), heart failure, pulmonary embolus, COPD, asthma exacerbations.
• Neurological: seizures (esp. temporal lobe), Parkinson disease, vestibular disorders, multiple sclerosis, traumatic brain injury.
• Infectious & inflammatory: encephalitis, HIV, systemic infections with delirium features.
• Metabolic & systemic: anaemia, electrolyte disturbances, renal/hepatic failure, porphyria.
• Medications/substances: corticosteroids, stimulants, sympathomimetics, and withdrawal states (benzodiazepine/alcohol rebound).

Clinical features suggesting secondary anxiety

• New-onset anxiety in later life (>40–50 years) or atypical age for primary anxiety disorder.
• Acute/subacute onset closely following a medical event, medication change, or infection.
• Prominent autonomic/physical features (palpitations, tremor, diaphoresis) disproportionate to psychological antecedents.
• Poor response to standard anxiety treatments until medical condition treated; symptoms fluctuating with medical status.
• Associated focal neurological signs, cognitive changes, syncope, unexplained systemic signs (weight loss, fever).

Assessment checklist

1. Detailed timeline: onset of anxiety relative to medical events, medication starts/stops and fluctuations—document dates when possible.
2. Targeted history & systems review: cardiac (palpitations, syncope), endocrine (weight change, heat intolerance), respiratory (dyspnoea), neurological symptoms (seizures, focal deficits) and substance use.
3. Physical examination: vitals (BP, HR, temperature), thyroid palpation, cardiovascular and neurological exam; look for signs pointing to systemic disease.
4. Baseline investigations guided by suspicion: ECG, thyroid function tests, fasting glucose/HbA1c, full blood count, electrolytes, renal/hepatic panel, chest imaging or D-dimer if PE suspected, toxicology screen, and targeted neuroimaging/EEG when indicated.
5. Collateral information and prior records are valuable—pharmacy lists, recent hospital notes and family reports help link symptoms to medical causes.

Management principles

• Prioritise treating the underlying medical condition: coordinate with the appropriate specialty (endocrinology, cardiology, neurology, infectious disease) — definitive management often reduces or resolves anxiety symptoms.
• Symptomatic psychiatric care: brief psychological strategies (CBT techniques, grounding, breathing) and short-term pharmacologic relief when necessary—tailor choice to medical comorbidity and interactions.
• Avoid harmful medications: benzodiazepines may be useful short-term for severe agitation but use cautiously in patients with respiratory disease, hepatic impairment or substance risk; prefer alternatives when possible.
• Address medication-induced anxiety: review prescription and OTC drugs; liaise with prescribing teams about dose adjustment or alternatives (e.g., steroid minimisation) rather than abrupt changes without specialist input.

Pharmacologic considerations

• SSRIs can be used for ongoing anxiety once medical causes stabilised and after liaison with treating teams; consider interactions (e.g., QT prolongation) and organ function when prescribing.
• Short-term benzodiazepines may be considered for acute severe anxiety while treating underlying cause, but keep time-limited with a clear taper plan and monitor for respiratory compromise.
• Avoid stopping essential medical treatments abruptly; coordinate safe adjustments with the treating team (e.g., steroid tapering protocols).

Practical tips for clinicians

• Document clear timelines and link symptom changes to medical events; request collateral records when uncertain.
• Use targeted investigations guided by clinical suspicion rather than blanket testing; prioritise safety and escalate rapidly for red flags.
• Coordinate care closely with treating medical teams—joint management plans reduce unnecessary medication changes and improve outcomes.

Key takeaways

• Consider a medical cause for new, atypical or late-onset anxiety—treating the underlying condition frequently reduces anxiety symptoms.
• Perform a focused assessment, use targeted investigations, and coordinate with specialists for definitive management.
• Provide symptomatic psychological and pharmacologic support cautiously while addressing the medical cause; escalate for medical instability or psychiatric emergencies.