title: Systematic appraisal of lactose intolerance as cause of increased need for oral thyroxine.
abstract: BACKGROUND
  An increased need for T4 has been described in patients with different gastrointestinal disorders. However, there is a lack of systematic studies assessing the need for T4 in hypothyroid patients with lactose intolerance, a widespread and often occult disorder.
  
  
  OBJECTIVE
  The objective of the study was to assess the replacement T4 dose required in hypothyroid patients with lactose intolerance.
  
  
  METHODS
  This was a cohort study.
  
  
  METHODS
  The study was conducted at an outpatient endocrinology unit in a University Hospital.
  
  
  METHODS
  The replacement T4 dose has been analyzed, from 2009 to 2012, in 34 hypothyroid patients due to Hashimoto's thyroiditis and lactose intolerance and being noncompliant with a lactose-free diet.
  
  
  METHODS
  An individually tailored T4 dose was measured.
  
  
  RESULTS
  In all patients with isolated Hashimoto's thyroiditis, target TSH (median TSH 1.02 mU/L) was obtained at a median T4 dose of 1.31 μg/kg/d. In patients with lactose intolerance, only five of 34 patients reached the desired TSH (median TSH 0.83 mU/L) with a similar T4 dose (1.29 μg/kg/d). In the remaining 29 patients, the T4 dose was progressively increased and the target TSH (median TSH 1.21 mU/L) was attained at a median T4 dose of 1.81 μg/kg/d (+38%, P < .0001). In six of these patients, other gastrointestinal disorders were diagnosed, and their median T4 requirement was higher (2.04 μg/kg/d; +55%; P = .0032). In the remaining 23 patients with isolated lactose intolerance, a median T4 dose of 1.72 μg/kg/d (+31% P < .0001) has been required to attain pharmacological thyroid homeostasis.
  
  
  CONCLUSIONS
  These findings show that lactose intolerance significantly increased the need for oral T4 in hypothyroid patients.
authors.affiliation: Department of Medico-Surgical Sciences and Biotechnologies (M.Cel., M.G.S., I.G., C.V., S.C.D.D., N.B., S.C., M.Cen.), "Sapienza" University of Roma, and Endocrinology Unit (M.Cel., S.C.D.D., N.B., L.G., M.Cen.), Azienda Unita Sanitaria Locale Latina, 00040, Latina, Italy.
authors.forename: Miriam
authors.initials: M
authors.lastname: Cellini
authors.forename: Maria Giulia
authors.initials: MG
authors.lastname: Santaguida
authors.forename: Ilenia
authors.initials: I
authors.lastname: Gatto
authors.forename: Camilla
authors.initials: C
authors.lastname: Virili
authors.forename: Susanna Carlotta
authors.initials: SC
authors.lastname: Del Duca
authors.forename: Nunzia
authors.initials: N
authors.lastname: Brusca
authors.forename: Silvia
authors.initials: S
authors.lastname: Capriello
authors.forename: Lucilla
authors.initials: L
authors.lastname: Gargano
authors.forename: Marco
authors.initials: M
authors.lastname: Centanni
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D050528:Diet, Carbohydrate-Restricted; D004305:Dose-Response Relationship, Drug; D054796:Drug Dosage Calculations; D005260:Female; D050031:Hashimoto Disease / Q000097:blood / Q000150:complications / Q000188:drug therapy; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications* / Q000188:drug therapy*; D007787:Lactose Intolerance / Q000150:complications*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data; D013974:Thyroxine / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D013974:Thyroxine