Can high or prolonged bismuth exposure cause neurotoxicity and kidney injury, and does urinary bismuth show brain burden?

Bismuth-containing medicines are usually used in short courses, but excessive, repeated, or prolonged exposure can lead to systemic accumulation and clinically important toxicity—particularly in older adults or those with reduced renal clearance.

Clinical toxicity and susceptibility

• Neurotoxicity is credibly linked to high or cumulative exposure. Reported bismuth encephalopathy includes confusion, behavioral change, dysarthria, ataxia, myoclonus, seizures, coma, and occasionally residual deficits. The pattern is concentration- and duration-related, and often improves after stopping bismuth.
• Kidney injury is most clearly documented after acute overdose. Cases include oliguric/anuric acute kidney injury requiring hemodialysis, with recovery sometimes taking weeks; rare severe overdoses have caused persistent proximal tubular dysfunction or irreversible renal failure.
• Renal impairment increases susceptibility: bismuth is substantially cleared by the kidneys, so impaired clearance can promote accumulation and raise neurologic as well as renal risk. In a 77-year-old, renal function and concurrent nephrotoxic exposures are particularly relevant to interpretation.

Exposure measurement and kinetics

• Urinary bismuth is best interpreted as evidence of absorbed bismuth undergoing recent or ongoing renal excretion. After intravenous bismuth citrate, about 55% of the dose was eliminated—predominantly in urine—within 47 hours; after oral products, urinary elimination peaks over the first 1–2 days.
• Detectability can persist well beyond exposure: approximately 60 days in one oral study and at least 3 months after six weeks of colloidal bismuth subcitrate. Timed 12- or 24-hour collections are more informative than a single spot sample; spot results require dilution/creatinine context.

Tissue retention and interpretation

• Bismuth has multicompartment kinetics: early urinary elimination can coexist with retained tissue stores. A terminal whole-body component after intravenous ^207Bi citrate had an approximately 1.9-year half-life.
• Kidney is a principal accumulation site; brain concentrations are lower but detectable. Blood and urine levels may correlate in encephalopathy cases, but do not distinguish acute from chronic exposure or quantify CNS deposition.

Bottom line

• The claim is supported: high/prolonged bismuth exposure can cause neurotoxicity and kidney injury, while urinary bismuth documents excretion/exposure—not brain or total-body burden. A urine result should be interpreted alongside timing, formulation, renal function, symptoms, and exposure history.