Pyridostigmine is an acetylcholinesterase inhibitor widely used for the symptomatic treatment of myasthenia gravis (MG). Cholinergic crisis is a rare but life-threatening adverse effect caused by excessive cholinergic stimulation. Since pyridostigmine is primarily excreted by the kidneys, standard doses may become excessive in the presence of severe renal impairment. We report a case of cholinergic crisis in an elderly patient on maintenance hemodialysis (HD) who exhibited significant weight loss and severe hypoalbuminemia. An 81-year-old male with acetylcholine receptor antibody-positive ocular MG on maintenance HD developed acute loss of consciousness and severe hypoxemia immediately after his usual pyridostigmine therapy (60 mg twice daily). He presented with marked miosis, profuse secretions, severe bradycardia, and hypotension. Arterial blood gas analysis revealed extreme hypercapnia, and serum cholinesterase (ChE) levels were markedly depressed (17 U/L; reference range: 240-486 U/L). Pyridostigmine was immediately discontinued, and atropine was administered via bolus followed by continuous infusion. During the period of hemodynamic instability, the patient required tracheal intubation and continuous hemodiafiltration (CHDF). Continuous atropine administration was gradually tapered and discontinued on day 12. A tracheostomy was performed on day 12, the patient was successfully weaned from mechanical ventilation on day 16, and he was discharged from the intensive care unit (ICU) on day 22. This case underscores that even standard doses of pyridostigmine can induce a cholinergic crisis in patients with severe renal failure receiving HD. Furthermore, significant weight loss and severe hypoalbuminemia may have increased the patient's vulnerability to severe cholinergic toxicity.
