| Test | Conventional | SI | Critical |
|---|---|---|---|
| Acetaminophen Level | 10–30 (therapeutic) µg/mL | 66–199 µmol/L | > 150 µg/mL at 4 h post-ingestion risks hepatotoxicity |
| Carbamazepine Level | 4–12 µg/mL | 17–51 µmol/L | > 12–15 µg/mL (ataxia, diplopia, drowsiness) |
| Digoxin Level | 0.8–2 ng/mL | 1–2.6 nmol/L | > 2.0 ng/mL is toxic (many target 0.5–0.9 in heart failure) |
| Lithium Level | 0.6–1.2 mEq/L | 0.6–1.2 mmol/L | > 1.5 mEq/L is toxic; > 2.0 is a medical emergency |
| Phenytoin Level | 10–20 µg/mL | 40–79 µmol/L | > 20 µg/mL (nystagmus, ataxia); > 30 confusion |
| Salicylate Level | 15–30 (anti-inflammatory) mg/dL | 1.1–2.2 mmol/L | > 40–50 mg/dL (tinnitus, tachypnea, acid–base disturbance) |
| Theophylline Level | 10–20 µg/mL | 56–111 µmol/L | > 20 µg/mL (nausea, tachycardia, seizures) |
| Valproic Acid Level | 50–100 µg/mL | 347–693 µmol/L | > 100–150 µg/mL (sedation, tremor) |
| Vancomycin Trough | 10–20 µg/mL | 7–14 µmol/L | > 20 µg/mL raises nephrotoxicity risk |
Panel
Therapeutic Drug Levels
Digoxin, lithium, phenytoin, vancomycin, and other drugs with narrow therapeutic windows. 9 tests, 9 with a critical value.
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