Toxicology & Poisoning

Convert blood ethanol between mg/dL, mg/L, g/L, g/dL and mmol/L, and see why a clinical serum result is not the same figure as a forensic whole-blood one.

Band a co-oximetry carboxyhaemoglobin percentage from a non-smoker’s baseline to a life-threatening level, and see why the number tracks the clinical picture so poorly.

Work out the number of digoxin immune Fab vials from a serum concentration or from a known ingested amount, with the empiric doses alongside — and the reason the serum digoxin becomes uninterpretable afterwards.

Band a serum digoxin concentration from subtherapeutic through to the thresholds for digoxin-specific antibody fragments, and see why toxicity remains a clinical diagnosis.

Convert a number of iron tablets into ingested elemental iron per kilogram against the 20 and 60 mg/kg thresholds, and avoid the salt-versus-elemental error that understates every dose.

Band a 12-hour post-dose serum lithium from subtherapeutic to severe toxicity, and see why the number matters less than whether the exposure is acute or chronic.

Band a co-oximetry methaemoglobin percentage against the thresholds for cyanosis, symptoms and methylene blue, and see why the pulse oximeter sticks near 85%.

Calculate a 1 or 2 mg/kg intravenous methylene blue dose for methaemoglobinaemia, with the volume of 1% solution, the repeat interval and the cumulative ceiling.

Work out the total intravenous acetylcysteine dose for the standard three-bag 21-hour regimen, with each bag’s dose, diluent volume and infusion time, and the reasons an infusion reaction is not a reason to stop.

Calculate the osmolal gap from measured osmolality, sodium, glucose, urea nitrogen and ethanol, and see why a normal gap does not exclude a toxic alcohol.

Convert a reported paracetamol ingestion into mg/kg against the 200 mg/kg or 150 mg/kg risk-assessment threshold, and see why the absolute dose matters as much as the weight-based figure.

Plot a paracetamol concentration against the 150 mg/L or the United Kingdom’s 100 mg/L treatment line between 4 and 24 hours after a single acute ingestion, and see when the nomogram does not apply at all.

Convert a salicylate concentration between mg/L, µmol/L, mg/dL and mmol/L — and read the number the way a toxicologist does, which is never on its own.

Estimate a methanol, ethylene glycol, isopropanol, acetone or propylene glycol concentration from the osmolal gap while a direct assay is awaited.