A 72-year-old woman is brought to the emergency department at 2 AM by her daughter, who reports that her mother became acutely confused and agitated over the past 6 hours. The daughter states that her mother was fine yesterday and has no prior history of cognitive problems. On examination, the patient is restless, disoriented to time and place, and her attention waxes and wanes. Vital signs show BP 145/92, HR 110, RR 22, Temp 38.5°C. Urinalysis shows pyuria and nitrites. Blood glucose is 280 mg/dL. What is the most likely diagnosis?

Explanation

## Acute Presentation with Identifiable Precipitants **Key Point:** This patient presents with acute onset confusion over 6 hours (not years), fluctuating attention, abnormal vitals, fever, and objective evidence of infection and hyperglycemia — all hallmarks of delirium, not dementia. ### Delirium vs Dementia: Critical Distinctions | Feature | This Case | Delirium | Dementia | |---------|-----------|---------|----------| | **Onset** | Acute (6 hours) | Acute (hours to days) | Insidious (months to years) | | **Course** | Fluctuating (waxes/wanes) | Fluctuating, variable | Steady, progressive | | **Consciousness** | Altered, agitated | Altered (hyperactive/hypoactive) | Preserved until late | | **Attention** | Impaired, waning | Markedly impaired | Relatively intact early | | **Vital signs** | Abnormal (fever, tachycardia, hypertension) | Often abnormal | Usually normal | | **Labs** | Abnormal (infection, hyperglycemia) | Often abnormal | Usually normal | | **Prior cognition** | Normal baseline | — | Gradual decline | | **Reversibility** | Often reversible | Often reversible | Irreversible | **High-Yield:** Acute onset + fluctuating consciousness + abnormal vitals + abnormal labs = **DELIRIUM** until proven otherwise. This patient has two clear precipitants: UTI (pyuria, nitrites) and uncontrolled diabetes (glucose 280). **Clinical Pearl:** Delirium is a medical emergency requiring identification and treatment of the underlying cause. UTI and hyperglycemia are common precipitants in elderly patients and are both treatable. ### Precipitants Identified 1. **Urinary tract infection** — pyuria, nitrites, fever, tachycardia 2. **Hyperglycemia** — glucose 280 mg/dL (likely undiagnosed diabetes or poor control) 3. **Acute systemic response** — elevated BP, HR, RR, fever **Mnemonic: I WATCH DEATH** (common delirium precipitants) — **I**nfection (UTI here), **W**ithdrawal, **A**cute metabolic (hyperglycemia here), **T**oxins, **C**NS pathology, **H**ypoxia, **D**eficiencies, **E**ndocrinopathy, **A**rrhythmias, **T**rauma, **H**ypertension.