The phenomenon of lymphocyte regression of phytohemagglutinin is a symptom of protein losing gastroenteropathy syndrome, also known as protein losing gastroenteropathy, or protein leaking gastroenteropathy or exudative gastroenteropathy. It is a syndrome caused by the loss of plasma protein, especially albumin, from the gastrointestinal mucosa due to various reasons. The main clinical manifestations are generalized swelling and hypoplasmosis. Small intestinal lymphadenopathy is often associated with immunoglobulin loss and abnormal cellular immunity, and the lymphocyte repertoire of phytohemagglutinin is diminished, making it susceptible to pulmonary infections. Functional dyspepsia is also a common cause of lymphocyte repertoire of phytohemagglutinin. The onset is associated with abnormal gastric sensory function, gastric motility disorders, gastrointestinal reflux, psycho-psychiatric factors, Helicobacter pylori (Hp), gastric mucosal inflammation, visceral allergy, and hypotonia of the vagus nerve. Patients with FD are generally accompanied by abnormal gastric compliance, with varying degrees of increased sensitivity to chemical, and mechanical stimuli. It is estimated that about 20-50% of FD patients are caused by gastric motility disorders, including delayed gastric emptying, abnormal interdigestive and digestive motility, abnormal food distribution in the stomach, and abnormal gastric spot. FD is one of the main causes of FD. Patients with FD are often accompanied by anxiety, insomnia, depression, and emotional agitation, so mental factors such as anxiety or depression and stressful states play a role in the development of FD and can be not only the cause of symptoms but also a trigger for exacerbation. In recent years, it has also been reported in the literature that Hp infection is associated with the development of FD and that eradication of Hp infection can improve the symptoms of FD. In addition, inflammation of the gastric mucosa, visceral hypersensitivity that increases the patient’s reactivity to various stimuli such as gastric acid, hypotonia of the vagus nerve resulting in impaired proximal gastric tolerance diastole and reduced contraction of the gastric sinus all play a role in the development of FD.