Psychotic disorder due to another medical condition — assessment to management (MEQ)

(i) Differential. Working concern is psychotic disorder due to another medical condition, with thyrotoxicosis high on the list (weight loss, heat intolerance, tachycardia, first psychosis after 50). Discriminate from delirium (attention preserved, not fluctuating over hours). Discriminate from primary late-onset schizophrenia-spectrum psychosis only after medical drivers are addressed. Substance/medication-induced remains if timeline fits drugs/steroids. Age and systemic signs raise secondary prior.[1][2]

(ii) Investigations. Tier 1: vitals/glucose, FBC, U&E, LFT, calcium, TSH (and free T4), B12/folate, urine drug screen, ECG, metabolic baseline before antipsychotic. Tier 2 justified here: full thyroid pathway already, plus HIV and syphilis serology as age-atypical first psychosis package; consider other directed tests if further clues appear.[2][4]

(iii) Imaging / LP / EEG / Abs. Image (MRI preferred if stable) because late first psychosis and systemic atypicality increase organic yield concern — defend selective imaging, not nihilism. EEG/LP/autoantibodies if seizures, fever/meningism, fluctuating consciousness, dyskinesias, speech reduction, rapid cognitive decline, or other AE red flags emerge; image before LP if raised ICP risk.[3][5]

(iv) Management. Medical priority: urgent endocrine review, beta-blockade/antithyroid plan per medical team — treat the driver. Risk assessment, capacity, collateral. Symptomatic: e.g. olanzapine 2.5–5 mg orally (or aripiprazole 5–10 mg) after ECG, with metabolic monitoring; shortest effective course as thyrotoxicosis settles. Disposition with medical cover.[4][1]

(v) AE red flags absent but critical. Examples: new seizures, orofacial/limb dyskinesias, speech reduction/mutism, autonomic instability, catatonia, fever with encephalitic course — any of these escalate to MRI/EEG/CSF and paired serum–CSF cell-based neuronal antibodies and neurology hand-off.[3][5]