Introduction: Bone mineral density (BMD) and fracture tendency are influenced by diet, activity, drugs, and hormones. Recent studies highlight an inverse relationship between serotonin and BMD, of uncertain mechanism.
Purpose: We investigated the relationship between serotonin metabolites and BMD in patients with sporadic neuroendocrine tumours (NETs), with and without the carcinoid syndrome.
Materials and methods: One-year prospective audit [ref 09/104]. All patients underwent DEXA-scanning as standard care for chronic malignancy. Data collection included clinical details, confounders influencing BMD and relevant investigation results.
Results: Of 41 eligible patients, 15 did not participate (too unwell, defaulted follow-up, declined participation) and 3 were excluded due to confounding factors. Twenty-three subjects were reviewed (15 females, 59.9±19 years, BMI 26.8±5.6, 8 males, 69.0±3.0 years BMI 30.6±5.6). The mean interval since diagnosis was 5.7 years (range 020 years); 16 had carcinoid syndrome, 7 did not. Thirteen had previous surgery, 4 chemotherapy, 11 radiolabelled-MIBG and 14 used somatostatin analogues.
Low BMD was not prominent: only 4 subjects had Z score >1 S.D. below the mean, with no unifying features in this group. 10 subjects had T score ≤−1.0 (osteopaenia or osteoporosis), all were females (P<0.01), and 7 had the carcinoid syndrome (P>0.05). Mean BMI was 25.4 cf 30.2 for those with normal T-score (P<0.05). The low T-score group did not differ from the group with a normal T-score in age, smoking, alcohol, medications, calcium or TSH but mean vitamin D was higher (77.8 vs 48.6 nmol/l; P=0.05). There was no difference in chromogranin-A (217.9 vs 281.9 pmol/l, P=0.6) or urine 5HIAA (360.8 vs 147.5 μmol/24 h, P=0.3). Z-scores did not differ between subjects with elevated or normal 5HIAA (P=0.28) or between subjects with and without the carcinoid syndrome (P=0.38).
Conclusion: NET patients do not show lower BMD related to serotonin metabolites or disease markers, although a larger cohort is required for confirmation of these preliminary data.