Background
Lupin or lupini beans, a type of yellow legume seed derived from Lupinus plant, belongs to Leguminosae family [1,2]. The specific genus of the beans is known as Lupinus and contains over 500 species that are distributed worldwide [1]. They are commonly used in Southern Europe, Latin America, and Middle East [2,3]. In the Middle East, these beans are commonly referred to as turmus [3]. Despite the bitter taste of lupin beans, they are highly nutritious and rich in protein. Hence, they are commonly used as snacks due to their nutritional value [3]. The bitter taste of lupin beans can be attributed to the presence of over 150 quinolizidine alkaloids. The predominant alkaloid in the beans is Lupanine, which is known for its high anticholinergic effects [3]. If the lupin beans are not appropriately debittered before ingestion, which involves removing the toxic alkaloids through cooking, washing, and rinsing for several days, it can result in lupin toxicity and the development of anticholinergic symptoms [1,3]. Based on a comprehensive literature search, this report is the first documented case of anticholinergic toxidrome after lupin bean ingestion in Saudi Arabia. Thus, we present a case of a 49-year-old man who developed anticholinergic symptoms following lupin bean ingestion and came to our emergency department in a university hospital. We also present a brief review of the relevant literature.
Case Description
A previously healthy 49-year-old Egyptian man presented to the emergency department with dry mouth, unsteadiness, constipation, and urinary retention for 6 hours. He was healthy with no medical conditions, allergies, or medications. He denied any history of trauma, recent alcohol consumption, or drug use. After further investigation into his food ingestion or poisoning, it was discovered that he had ingested around 400 g of bitter lupin beans as a snack within a 1-hour period, approximately 4-6 hours prior to the symptom’s onset.
On physical examination, the patient was oriented, conscious, and alert, showing no signs of pain or distress. His vital signs were all normal, as follows: temperature: 36.5°C, respiratory rate: 18 breaths per minute, oxygen saturation: 98%, blood pressure: 130/84 mmHg, and heart rate: 91 beats per minute (bpm). Cardiovascular, pulmonary, gastrointestinal, and neurological examinations were all normal. Eye examination revealed fixed, dilated, non-reactive pupils bilaterally, blurry vision for near objects in both eyes, and normal eye movement bilaterally. Laboratory test results were normal, including venous blood gas, complete blood count, liver function test, and random blood glucose.
The patient received one l of Ringer’s lactate intravenously and was closely observed in the emergency department with continuous monitoring of vital signs. Gradually, over a 3-hour period, all of the patient’s symptoms and signs resolved with fluid management alone. Hence, the patient was discharged home following his improvement.
Discussion
Lupanine, the predominant alkaloids in lupin beans, can induce anticholinergic toxidrome [3]. Alkaloid-rich lupin beans produce systemic manifestations by inhibiting both nicotinic acetylcholine receptors and muscarinic receptors [2]. Consequently, anticholinergic symptoms such as mydriasis, dry mouth, tachycardia, and constipation may develop [2].
We conducted a comprehensive search in PubMed and all the databases available in Clarivate to identify all case reports published in English on March 9, 2024. Then, we reviewed a total of 12 cases of anticholinergic syndrome following bitter lupin consumption, as presented in Table 1. The cases included ranged from the first case report published in 1995 to the most recent case in 2021. The average age of the cases was 46.5 years. Most cases were adults, while two cases were of pediatric age, specifically 6 years and 12 years old [2,4]. Of the 12 cases reviewed, only 3 were male [2,5,6]. The most commonly reported clinical features were bilateral mydriasis and dryness of the oral mucosa and skin. The majority of cases were stable. Hence, supportive management, observation, and discharge were done in most cases. However, there was one severe case where the patient was administered antiepileptic medication for a continuous generalized tonic-clonic seizure. Then, the patient was admitted to the intensive care unit for further care [2]. Most cases reported lupin toxicity from ingesting the beans themselves, except 4 cases involved different methods of consumption of lupin [6-8].
| CASE | REFERENCE | AGE (IN YEARS), GENDER | CLINICAL FEATURES | MANAGEMENT | PATIENT’S CONDITION PRIOR TO PRESENTATION | OUTCOME | METHOD OF TOXICITY |
|---|---|---|---|---|---|---|---|
| 1 | Ozkaya et al. [2] | 12, male | Antiepileptic medications Intensive care unit admission. | Healthy | Discharged | Lupin beans ingestion | |
| 2 | Lahoud et al. [3] | 50, female | Supportive management | Healthy | Discharged | Lupin beans ingestion | |
| 3 | Al-Abdouh, Md et al. [10] | 40, female | Supportive management | Healthy | Discharged | Lupin beans ingestion | |
| 4 | Li et al. [6] | 63, male | Supportive management | NA | Discharged | Ingestion of water containing lupin bean extract | |
| 5 | Daverio et al. [4] | 6, female | Supportive management | Healthy | Discharged | Lupin beans ingestion | |
| 6 | Jamali [5] | 44, male | Supportive management | NA | Discharged | Lupin beans ingestion | |
| 7 | Pingault et al. [7] | 73, female | NA | NA | NA | Eating scones prepared with lupin flour | |
| 8 | Pingault et al. [7] | 66, female | NA | NA | NA | Eating pancakes prepared with lupin flour | |
| 9 | Litkey & Dailey [9] | 46, female | Supportive management | Hyperlipidemia | Discharged | Lupin beans ingestion | |
| 10 | Di Grande et al. [1] | 51, female. | Supportive management | NA | Discharged | Lupin beans ingestion | |
| 11 | Tsiodras et al. [8] | 72, female | Supportive management | Diabetes mellitus | Discharged | Lupin beans ingestion | |
| 12 | Lowen et al. [11] | 35, female | Supportive management | NA | Discharged | Lupin beans ingestion |
The diagnosis of lupin toxicity is primarily based on history taking and physical examination [9]. Therefore, in cases where there is a strong suspicion of food poisoning or ingestion of a toxin, a significant focus on food history is crucial.
The management is based on supportive treatment and observation. When a patient presents early, within 1-2 hours of ingesting the beans, activated charcoal or gastric lavage may benefit the patient [9]. Although asymptomatic hypertension or sinus tachycardia does not require treatment in most cases, beta-1 cardioselective beta-blockers such as metoprolol or esmolol can be used when required [9]. Agitation and anxiety associated with anticholinergic toxidrome can be managed with benzodiazepines [5,9]. Whereas physostigmine is used in cases of severe seizure refractory to benzodiazepines and hypotension with dysrhythmia [1,9].
In our case, the patient presented to the emergency department 4-6 hours after ingesting lupin beans. Prior to this event, he was healthy with no medical conditions. He presented with anticholinergic features such as dry mouth, unsteadiness, constipation, urinary retention, and bilateral mydriasis. He was closely monitored and managed conservatively. As his clinical status improved, he was discharged home.
Conclusion
We report the first case in Saudi Arabia of an unusual presentation of anticholinergic toxidrome after lupin bean ingestion. The bitter taste of lupin bean is due to the presence of more than 150 quinolizidine alkaloids. Lupanine, the most prevalent alkaloid in lupin beans, is known for its high anticholinergic effects. Therefore, bitter lupin should be debitterd before consumption to avoid lupin toxicity. The diagnosis of such a condition can be challenging; thus, a detailed history taking of suspected food-related diseases should be done to reach the correct diagnosis.