Division of Immunology, Transplants and Infectious Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
Nutrients. 2022 Apr 5;14(7):1513. doi: 10.3390/nu14071513.
Background: Histamine Intolerance (HIT) is a multifaceted pseudoallergic disorder possibly due to defective histamine metabolism. Diamine oxidase (DAO) contributes to histamine degradation and can be measured in the serum. The role of DAO measurement in the diagnostic work-up of HIT still remains unclear, and conflicting results have been reported in the literature. Therefore, we aimed to evaluate the possible clinical usefulness and consistency of DAO value ranges as provided by the assay manufacturer and verify whether they could predict the response to treatment. Methods: We retrospectively analyzed 192 outpatients with HIT symptoms and measured serum DAO values at baseline. Patients were prescribed either with low-histamine diet and/or enzymatic supplementation according to symptom severity and re-evaluated six to eight months later. Patients were stratified into three groups according to DAO levels: <3 U/mL, 3−10 U/mL, and >10 U/mL. HIT severity was assessed on a scale of 1 to 5 before and after treatment. Results: A total of 146 patients completed the study. Gastrointestinal and cutaneous symptoms, often associated with headache, were more frequent in subjects with DAO < 10 U/mL. Symptom severity and DAO ranges were correlated. Patients with intermediate DAO levels (3−10 U/mL) showed a more complex clinical phenotype but also a more significant improvement in symptom severity (score reduction 50%, interquartile range (IQR) = 33−60%) when compared to patients with low DAO (40%, IQR = 20−60%; p = 0.045) or high DAO (33%, IQR = 0−50%; p < 0.001). Complex clinical phenotypes were also more frequent in patients with intermediate DAO levels. Conclusions: HIT is characterized by typical symptoms and low levels of DAO activity. Symptom severity was associated with the degree of DAO deficiency. Patients with DAO values between 3 and 10 U/mL show the best response to treatment (low-histamine diet and/or DAO supplementation). DAO value could arguably be considered as a predictor of clinical response to treatment. Prospective studies are needed to confirm these data.
组胺不耐受（HIT）是一种多方面的假性过敏疾病，可能是由于组胺代谢缺陷所致。二胺氧化酶（DAO）有助于组胺的降解，可以在血清中测量。DAO 测量在 HIT 的诊断中的作用仍不清楚，文献中报道的结果也存在冲突。因此，我们旨在评估检测制造商提供的 DAO 值范围的可能临床用途和一致性，并验证它们是否可以预测治疗反应。
我们回顾性分析了 192 例有 HIT 症状的门诊患者，并在基线时测量了血清 DAO 值。根据症状严重程度，患者被开低组胺饮食和/或酶补充剂，并在 6-8 个月后重新评估。根据 DAO 水平将患者分为三组：<3 U/mL、3-10 U/mL 和>10 U/mL。治疗前后对 HIT 严重程度进行 1-5 分评分。
共有 146 例患者完成了研究。胃肠道和皮肤症状，常伴有头痛，在 DAO<10 U/mL 的患者中更为常见。症状严重程度和 DAO 范围相关。中间 DAO 水平（3-10 U/mL）的患者表现出更复杂的临床表型，但症状严重程度的改善更为显著（评分降低 50%，四分位距（IQR）=33%-60%），与 DAO 水平较低的患者（40%，IQR=20%-60%；p=0.045）或 DAO 水平较高的患者（33%，IQR=0%-50%；p<0.001）相比。中间 DAO 水平的患者也更常出现复杂的临床表型。
HIT 的特征是典型的症状和低 DAO 活性。症状严重程度与 DAO 缺乏程度相关。DAO 值在 3-10 U/mL 之间的患者对治疗反应最佳（低组胺饮食和/或 DAO 补充）。DAO 值可作为治疗反应的预测因子。需要前瞻性研究来证实这些数据。
