There are two main reasons for increased gastrin-releasing peptide precursor, namely, abnormal renal function and neoplastic diseases. 1. Abnormal renal function: In patients with non-neoplastic diseases, some of them may have increased levels of gastrin-releasing peptide precursor, but the increase is usually mild, and the reason is mainly due to chronic renal insufficiency, acute kidney injury and other factors. 2. Tumor diseases: it is the main reason for the increase of gastrin-releasing peptide precursor, such as small-cell lung cancer, neuroendocrine tumors, especially in small-cell lung cancer, which has a high degree of specificity, and can be used for early diagnosis of small-cell lung cancer, monitoring the treatment of the disease, and assessing the prognosis. In addition, due to individual differences, if some patients have a slight increase in gastrin-releasing peptide precursor, it may not be caused by the disease, and need to be combined with other tests to determine, we suggest that patients actively cooperate with the doctor’s examination, identify the cause, and then carry out treatment in a timely manner.