title: Are serotonin metabolite levels related to bone mineral density in patients with neuroendocrine tumours?
abstract: BACKGROUND
  Bone mineral density (BMD) is influenced by multiple factors. Recent studies have highlighted a possible relationship between serotonin and BMD. Patients with neuroendocrine tumours (NETs) frequently have elevated urinary 5-hydroxy-indoleacetic acid (5-HIAA) levels, a serotonin metabolite. Evaluation of the relationship between 5-HIAA and BMD in patients with NETs may provide insights into the relationship between serotonin and BMD.
  
  
  METHODS
  One-year audit of consecutive patients with NETs within two institutions. Relationships between urinary 5-HIAA and dual X-ray absorptiometry (DEXA)-scan-measured BMD were investigated by group comparisons, correlation and regression.
  
  
  RESULTS
  Of 65 patients with NETs, 19 did not participate or were excluded. Of 46 subjects evaluated (48·9% males, 63·8 ± 10·5 years, BMI 26·6 ± 4·4 kg/m(2) ) with 32 gastrointestinal, 9 pancreatic, 3 pulmonary and 2 ovarian NETs, 72·3% had the carcinoid syndrome. Median interval from diagnosis was 4·0 years (IQR 2·0-6·0); 41·3% had osteoporosis and 32·6% osteopaenia (WHO definition). The group with a higher urinary 5-HIAA had a lower hip BMD (total T-score and Z-score), confirmed on individual analysis (Spearman's rank correlation -0·41, P = 0·004; -0·44, P = 0·002, respectively); urinary 5-HIAA was not found to be an independent predictor for BMD on multiple linear regression analysis.
  
  
  CONCLUSIONS
  These data of patients with NETs with higher serotonin metabolites having a lower BMD at the hip in group and individual comparisons, warrants further evaluation. Urinary 5-HIAA measurement alone cannot be used to predict future BMD. A larger cohort with prospective design including fractures as a clinical outcome will aid these data in determining whether patients with NETs should be subject to targeted osteoporosis prevention.
authors.affiliation: Department of Endocrinology, Barts & the London School of Medicine, QMUL, London, UK.
authors.forename: Piya
authors.initials: P
authors.lastname: Sen Gupta
authors.forename: Simona
authors.initials: S
authors.lastname: Grozinsky-Glasberg
authors.forename: William M
authors.initials: WM
authors.lastname: Drake
authors.forename: Scott A
authors.initials: SA
authors.lastname: Akker
authors.forename: Les
authors.initials: L
authors.lastname: Perry
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Grossman
authors.forename: Maralyn R
authors.initials: MR
authors.lastname: Druce
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density; D005260:Female; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism / Q000652:urine*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018358:Neuroendocrine Tumors / Q000378:metabolism* / Q000652:urine*; D011446:Prospective Studies; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid