A clear understanding of some relevant examination methods of the disease can enable us to shorten the required examination time for the patients and thus increase the valuable treatment time for them, and I believe you can imagine how helpful it is for their treatment. The following is the introduction of the examination methods related to carcinoid syndrome. Because 99% of 5-HT is converted into 5-HIAA in the body and excreted through urine, it is of diagnostic value to measure the increase of 5-HIAA in urine for 24h. Most of these patients have blood concentration >120μg/L and urinary 5-HIAA exceeds 30mg/24h urine. More than 50mg/24h urine has a confirmatory value. If the urinary 5-HT or 5-HTP (5-hydroxytryptophan) is found to be low, the urinary 5-HT or 5-HTP should be further determined by paper chromatography to determine whether there is an increase in 5-HT or 5-HTP. The 5-HT in tumor tissue of carcinoid tumor is significantly elevated. This method is more sensitive than urinary 5-HIAA measurement. 4.Pentagastrin excitation test Pentagastrin excitation test is helpful for the diagnosis of carcinoid syndrome. After 0.6μg/kg intravenous injection of Pentagastrin, 5-HT was measured in blood at 1, 3, 5, 10 and 15 min. The increase of blood 5-HT in all cases was >40% or >50μg/L. 5.Rough sieve test was performed by putting a drop of patient’s urine on filter paper and then spraying azo P-dinitrobenzylamine. If it appears red, it is positive, indicating an increase in 5-HIAA in urine. If it is purple, it is pheochromocytoma, and this test helps to identify the two. 6, the determination of 5-HT in whole blood, plasma or platelets can help diagnose, but the method is cumbersome and difficult to promote the application.