Consultation-Liaison and Organic Psychiatry
Approach
Consultation-liaison psychiatry asks: is the psychiatric presentation primary or secondary to a medical condition/substance? Always screen for organic causes of psychiatric symptoms - the classic list includes delirium, hypoglycaemia, hypoxia, electrolyte disturbance, infection, thyroid disease, B12 deficiency, medication effects, and neurological lesions. Know that delirium is the most common organic psychiatric syndrome in hospital and is under-recognised.
High-yield syndromes
- Delirium: acute, fluctuating, inattention; manage cause, environment, and use antipsychotics cautiously and briefly.
- Serotonin syndrome vs NMS (see basic sciences).
- Catatonia: immobility, mutism, negativism, posturing, waxy flexibility; treat with benzodiazepines, ECT if malignant.
- Psychiatric effects of medical illness: depression in stroke, Parkinson's, cancer, HIV; anxiety in cardiac disease.
- Medically unexplained symptoms/somatic symptom disorder: assess, avoid over-investigation, manage collaboratively.
Traps
- Attributing new psychiatric symptoms in a medically ill patient to a primary psychiatric disorder.
- Missing drug-induced psychiatric symptoms (steroids, anticholinergics, interferon, levodopa).
- Forgetting that capacity assessment is a clinical, decision-specific judgement, not a global label.
Rule of thumb
In any hospital patient with new psychiatric symptoms, run the organic screen first: vitals, glucose, electrolytes, infection screen, medication review, and neurological examination before a psychiatric diagnosis.