JCEM：类癌综合征患者的高循环血清素与骨密度降低无关

肠源性血清素被视为是骨形成的一个调节因子，在啮齿动物抑制肠道血清素合成可以增加骨形成。在人类，良性神经内分泌肿瘤可以产生非常高水平的循环血清素，因此，提供了一个血清素过量的模型。为了确定类癌综合症患者与健康对照者相比，是否有较低的骨形成指标、较低的骨密度（BMD）或较差的骨结构，来自英国谢菲尔德北区综合医院骨代谢中心的Jennifer S Walsh博士及其团队进行了一项研究，该研究发现类癌综合征患者的高循环血清素与临床明显的骨密度降低、骨强度下降或骨形成指标降低无关。该研究结果在线发表在2013年4月30日的美国《临床内分泌代谢杂志》（The journal of clinical endocrinology & metabolism）上。
该研究是在25例类癌综合征患者和25例健康对照者（与类癌综合征患者性别、年龄、身高和BMI匹配的个体）中进行的一项横断面研究。该研究测量受试者全血和血浆的循环血清素，以及血浆和尿液的5–羟基吲哚乙酸（5HIAA）。通过双能X线吸收测定法（DXA）测量腰椎和髋关节骨密度；高分辨外周定量CT（pQCT）测量桡骨和胫骨；血清骨钙蛋白、I型前胶原氨基端前肽(PINP)和I型胶原羧基端肽（CTX）评价骨转换。
该研究结果表明，所有血清素和5HIAA的测量在类癌患者高于对照组。骨密度和骨结构的测量在病例组和对照组之间没有显著差异。骨钙蛋白在病例组高于对照组（26.0 vs 21.1ng/ml，P=0.02）。病例组与对照组之间的PINP和CTX没有差异。在类癌综合征患者，血浆5HIAA与骨钙蛋白呈正相关。在对照组，全血血清素与骨钙蛋白、PINP和CTX呈正相关（R值0.40至0.47，所有P＜0.05）。
该研究发现，类癌综合征患者的高循环血清素与临床明显的骨密度降低、骨强度下降或骨形成指标降低无关。

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Circulating serotonin and bone density, structure and turnover in carcinoid syndrome
Context
Gut-derived serotonin has been proposed as a regulator of bone formation, and inhibition of gut serotonin synthesis increases bone formation in rodents. Carcinoid neuroendocrine tumors can produce very high levels of circulating serotonin and so offer a model of serotonin excess in humans.
Objectives
To determine if patients with carcinoid syndrome have lower bone formation markers, lower bone density or poor bone structure compared with healthy controls.
Design
We conducted a cross-sectional study of 25 patients with carcinoid syndrome and 25 healthy controls, individually matched to carcinoid patients by gender, age, height and BMI.
Outcome measures
We measured circulating serotonin in blood and plasma, and 5HIAA in plasma and urine. We measured lumbar spine and hip BMD by DXA, the distal radius and tibia with high-resolution pQCT, and bone turnover with serum osteocalcin, PINP and CTX.
Results
All measures of serotonin and 5HIAA were higher in carcinoid patients than in controls. No measures of bone density or bone structure differed significantly between cases and controls. Osteocalcin was higher in cases than controls (26.0 vs 21.1 ng/ml, p 0.02). PINP and CTX did not differ between cases and controls. In patients with carcinoid syndrome, plasma 5HIAA was positively correlated with osteocalcin. In controls, whole blood serotonin was positively correlated with osteocalcin, PINP and CTX. (R values 0.40 to 0.47, all p <0.05.)
Conclusions
High circulating serotonin in carcinoid syndrome is not associated with clinically significant lower bone density, poorer bone structure or lower bone formation markers.