Tohmola Niina, Johansson Anna, Sane Timo, Renkonen Risto, Hämäläinen Esa, Itkonen Outi
Haartman Institute, University of Helsinki, Helsinki, Finland HUSLAB, Helsinki University Central Hospital, Helsinki, Finland
Helsinki Metropolia University of Applied Sciences, Helsinki, Finland.
Ann Clin Biochem. 2015 Jul;52(Pt 4):428-33. doi: 10.1177/0004563214554842. Epub 2014 Sep 23.
Dietary serotonin increases urinary secretion of 5-HIAA. A falsely elevated 5-HIAA may lead to incorrect suspicion of a neuroendocrine tumour. Therefore, we determined the effect and duration of dietary serotonin on serum 5-HIAA concentration. We also studied the distribution of 5-HIAA in serum fractions.
We used serum samples from healthy volunteers (31 women and four men). All test subjects avoided serotonin-containing foods for three days before sample collection. They then ate either pineapple, banana, kiwi fruit, tomato or walnuts and additional blood samples were taken after 2, 4, 6, 24, 48 and 72 h. To study the distribution of 5-HIAA in serum, samples from a healthy individual, a test person who had ingested walnuts, and from a neuroendocrine tumour patient were fractionated by gel filtration chromatography. The fractions were analysed for 5-HIAA.
Serum 5-HIAA concentration increased significantly (P ≤ 0.001) within 2 h after ingestion of serotonin-containing food. After 2 h, 5-HIAA concentration started to decrease and reached the baseline concentration within 24 h. A calculated half-life of 5-HIAA in circulation was 1.3 h. In fractionated serum, 5-HIAA was found not only in free form but also in the albumin and α2-globulin fractions.
The increase of serum 5-HIAA caused by dietary serotonin is significant but transient. Therefore, serotonin-containing foods should be avoided for one day before blood sampling. In serum, 5-HIAA is free and apparently bound to albumin. Minor amounts were also found in the α2-globulin fraction. Our liquid chromatography tandem mass spectrometry assay measures free 5-HIAA in serum.
饮食中的血清素会增加5-羟吲哚乙酸（5-HIAA）的尿分泌。5-HIAA假性升高可能导致对神经内分泌肿瘤的错误怀疑。因此，我们确定了饮食中血清素对血清5-HIAA浓度的影响及持续时间。我们还研究了5-HIAA在血清各组分中的分布。
我们使用了健康志愿者（31名女性和4名男性）的血清样本。所有受试对象在样本采集前三天避免食用含血清素的食物。然后他们食用菠萝、香蕉、猕猴桃、番茄或核桃，并在2、4、6、24、48和72小时后采集额外的血样。为了研究5-HIAA在血清中的分布，通过凝胶过滤色谱法对一名健康个体、一名食用核桃的受试人员以及一名神经内分泌肿瘤患者的样本进行分离。对各组分进行5-HIAA分析。
摄入含血清素食物后2小时内，血清5-HIAA浓度显著升高（P≤0.001）。2小时后，5-HIAA浓度开始下降，并在24小时内恢复到基线浓度。计算得出5-HIAA在循环中的半衰期为1.3小时。在分离的血清中，不仅发现了游离形式的5-HIAA，还在白蛋白和α2球蛋白组分中发现了5-HIAA。
饮食中的血清素引起的血清5-HIAA升高显著但短暂。因此，采血前一天应避免食用含血清素的食物。在血清中，5-HIAA是游离的，且明显与白蛋白结合。在α2球蛋白组分中也发现了少量5-HIAA。我们的液相色谱串联质谱分析法可测定血清中的游离5-HIAA。
