A 46-year-old man presents to the Emergency Department with abdominal pain, diarrhoea and vomiting. He feels weak and reports a new-onset tremor. He has just come back from a cruise in the Caribbean. His only past medical history is bipolar disorder, for which he takes lithium and newly diagnosed hypertension, for which his GP has recently started him on ramipril.

What intervention should form the basis of your treatment?

Options:
explanation: Benzodiazepines such as lorazepam are used in the treatment of serotonin syndrome, which occurs as a result of high levels of serotonin in the body. It is an uncommon but serious side effect of certain medications used to treat psychiatric conditions such as depression (for example, citalopram, fluoxetine, sertraline). This patient's symptoms could be explained by serotonin syndrome; however, he is not taking any medications that might induce this
name: Intravenous lorazepam
label: e
answer: no
explanation: Oral antibiotics from the tetracycline, fluoroquinolone or macrolide class would be a reasonable treatment if suspecting an atypical pneumonia such as legionnaires disease. Legionnaires disease is associated with water from ventilation systems. Most people become infected when they inhale microscopic water droplets containing legionella bacteria, e.g., the spray from a shower, faucet or whirlpool, or water from the ventilation systems. Whilst atypical pneumonia such as legionella may present with gastrointestinal symptoms, it would be uncommon to have no respiratory symptoms, and there is no history of a fever. It would also not account for the tremor that the patient has reported
name: Oral doxycycline
label: b
answer: no
explanation: Chelation is a treatment for heavy metal poisoning, for example, with lead or mercury. It is not used in the treatment of lithium toxicity, and there is no evidence that this patient has come into contact with any heavy metals
name: Chelation therapy
label: d
answer: no
explanation: This patient is showing signs of lithium toxicity, for which intravenous fluids is the mainstay of treatment. Common causes of lithium toxicity include dehydration, alcohol intake and angiotensin-converting enzyme inhibitors (ACE-i) such as ramipril as they reduce glomerular filtration rate (GFR) and enhance the tubular reabsorption of lithium (thus increasing plasma concentrations of lithium). In addition, the patient has recently been through a time zone change and therefore may have taken his medications at different times to his usual; therefore, one should be alert to the possibility of lithium toxicity
name: Intravenous fluids
label: a
answer: yes
explanation: This patient's presentation could be due to traveller's diarrhoea; however, it would not explain the tremor. If traveller's diarrhoea was the diagnosis, then management is mainly supportive (for example, with intravenous fluids). Antibiotics are generally not indicated in traveller's diarrhoea, however in some cases, they have been shown to improve symptoms, and a fluoroquinolone such as azithromycin may be a reasonable choice. Still, it would not be the basis of treatment
name: Oral azithromycin
label: c
answer: no

Correct answer: a


Learning point: Intravenous fluids are the mainstay of treatment for lithium toxicity, as they help to increase hydration, enhance renal clearance, and facilitate the elimination of excess lithium from the body.