Accidental digitoxin intoxication: an interplay between laboratory and clinical medicine
A married couple (a 61 year old man and his wife aged 60) arrived at the Maggiore della Carità Hospital (Novara, Italy) because of diarrhea, nausea and vomiting for 4 days; they also complained weakness, fatigue and visual hallucinations (orange and purple halo around lights). The subjects reported the ingestion of some leaves of a plant that they supposed to be “donkey ears” (Plantago minor; scientific name Plantago lanceolata) a week before; they collected these herbs still in leaf buds and used them for tea and for a pasta sauce.\nIn the emergency room physical examination showed bradycardia in both, most pronounced in the male (35/min) combined with hypotension (80/60 mmHg blood pressure). ECG examination disclosed sinus rhythm and repolarization abnormalities (scooping of the ST-T complex) in both and a 2:1 AV block was detected in the male patient. He was treated with atropine (two doses of 0.5 mg, i. v.) without any effect.\nECG pattern, history and clinical findings were consistent with digitalis toxicity (), but standard plasma digoxin assay was repeatedly negative for both patients (both at the admission and after 4 hours). Nonetheless, given the high probability of digitalis toxicity, even if not confirmed by a laboratory test, after consulting with the clinical pathologist that could not exclude or confirm at that time glycoside intoxication, the male patient was treated with anti-digoxin antibodies (Digifab®, Digoxin Immune Fab (Ovine), 3 vials containing 40 mg of antibody each, infused i. v. in 30 minutes), in addition to supportive care (–). The AV block was reverted in two hours after the beginning of treatment. Anti-digoxin antibodies were not administered to woman because she was clinically stable. The presence of cardiac glycosides in plasma of both patients was subsequently confirmed by Liquid Chromatography-Mass Spectrometry (LC-MS/MS) (,). Digitoxin was identified in both patients (woman: 50 ng/mL, man: 100 ng/mL) at toxic plasma levels compatible with the severity of the clinical picture (digitoxin therapeutic range: 10–30 ng/mL) (). Colchicines and protoveratine, as possible alternative toxic drugs, were excluded by LC-MS/MS patient plasma analysis. Digoxin was confirmed as negative by LC-MS/MS. After 48 hours of monitoring, both patients were discharged. Interestingly, a sample of the plants collected by the couple, brought to the Hospital some weeks later, was analyzed by an expert botanist and found to be Digitalis purpurea.