title: Bile duct stone procedures are more frequent in patients with hypothyroidism. A large, registry-based, cohort study in Finland.
abstract: OBJECTIVE
  Delayed bile flow may induce the formation/accumulation of common bile duct stones (CBDS). Bile flow is delayed in hypothyroidism, partly due to insufficient sphincter of Oddi relaxation. Patients with CBDS have higher incidences of clinical and subclinical hypothyroidism compared to healthy controls and gallbladder stone patients. The aim of this large registry-based study was to investigate the prevalence of CBDS in patients with diagnosed hypothyroidism compared to age-, sex- and living area-adjusted glaucoma (control) patients.
  
  
  METHODS
  Between 1987 and 2001, all patients with approved Special Medical Coverage (SMC) for hypothyroidism or glaucoma, and without other SMC approvals, were included. The glaucoma (control) cohort was adjusted for age, sex and area of residence. For each patient, onset of SMC, all prescription drugs and treatments for CBDS were noted.
  
  
  RESULTS
  A total of 14,334 patients in each group met the inclusion criteria. Thirty-three patients (0.23%) in the hypothyroidism cohort and 23 (0.16%) in the glaucoma cohort had been treated for CBDS (p = 0.018). The groups did not differ in the number of CBDS treatments before the diagnosis of hypothyroidism or glaucoma. However, after the diagnosis of hypothyroidism or glaucoma there were significantly more CBD stone patients in the hypothyroid cohort (n = 25) than in the glaucoma cohort (n = 14) (p < 0.05).
  
  
  CONCLUSIONS
  Diagnosed hypothyroidism is a significant risk factor for CBDS. We hypothesize that CBD stone formation begins during the untreated period and develops/matures even after the medication has been initiated, raising the question of the efficiency of treatment in this respect. When treating CBDS patients, one should be aware of the possible hypothyroid background.
authors.affiliation: Department of Gastroenterology and Alimentary Tract Surgery, Tampere University Hospital, Tampere, Finland. johanna.laukkarinen@fimnet.fi
authors.forename: Johanna
authors.initials: J
authors.lastname: Laukkarinen
authors.forename: Juhani
authors.initials: J
authors.lastname: Sand
authors.forename: Ville
authors.initials: V
authors.lastname: Autio
authors.forename: Isto
authors.initials: I
authors.lastname: Nordback
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005387:Finland; D042882:Gallstones / Q000209:etiology*; D006801:Humans; D007037:Hypothyroidism / Q000150:complications*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors