PT  - JOURNAL ARTICLE
AU  - Richard Fagan
AU  - Syed Sabeeh Najam Bokhari
AU  - Faisal Inayat
TI  - Vitamin D and vitamin B<sub>12</sub> deficiencies in patients with small intestinal carcinoid tumour: is opioid use disorder a confounding factor in the diagnosis?
AID  - 10.1136/bcr-2018-227430
DP  - 2019 Mar 01
TA  - BMJ Case Reports
PG  - e227430
VI  - 12
IP  - 3
4099  - http://casereports.bmj.com/content/12/3/e227430.short
4100  - http://casereports.bmj.com/content/12/3/e227430.full
SO  - BMJ Case Reports2019 Mar 01; 12
AB  - Carcinoid tumours have the ability to secrete various peptides and bioamines that lead to carcinoid syndrome manifested as cutaneous flushing, diarrhoea, bronchial constriction and cardiac involvement. The deficiencies of vitamins D and B12 have previously been reported in patients with carcinoid tumours presumably due to chronic diarrhoea associated with the carcinoid syndrome. Herein, we chronicle the case of a patient with opioid use disorder who presented with small bowel obstruction that was found to be caused by a midgut carcinoid tumour. Laboratory studies revealed deficiencies of vitamins D and B12 even though he denied diarrhoea and had no other aetiology of deficiencies of these vitamins. Additionally, this paper presents a review of the published medical literature pertaining to clinical features, diagnostic investigations and treatment of intestinal carcinoid tumours and explores possible explanations for the observed deficiencies in these patients.