title: No impact of dietary iodine restriction in short term development of hypothyroidism following fixed dose radioactive iodine therapy for Graves' disease.
abstract: BACKGROUND
  The increased incidence of autoimmune thyroid disease with increasing dietary iodine intake has been demonstrated both epidemiologically and experimentally. The hypothyroidism that occurs in the first year following radioactive iodine therapy is probably related to the destructive effects of the radiation and underlying ongoing autoimmunity.
  
  
  OBJECTIVE
  To study the outcomes at the end of six months after fixed dose I, (131)therapy for Graves' disease followed by an iodine restricted diet for a period of six months.
  
  
  METHODS
  Consecutive adult patients with Graves' disease planned for I(131) therapy were randomized either to receive instructions regarding dietary iodine restriction or no advice prior to fixed dose (5mCi) I(131) administration. Thyroid functions and urinary iodine indices were evaluated at 3(rd) and 6(th) month subsequently.
  
  
  RESULTS
  Forty seven patients (13M and 34F) were assessed, 2 were excluded, 45 were randomized (Cases 24 and Controls 21) and 39 patients completed the study. Baseline data was comparable. Median urinary iodine concentration was 115 and 273 μg/gm creat (p = 0.00) among cases and controls respectively. Outcomes at the 3(rd) month were as follows (cases and controls); Euthyroid (10 and 6: P = 0.24), Hypothyroid (3 and 5: P = 0.38) and Hyperthyroid (7 and 8: P = 0.64). Outcomes at the end of six months were as follows (cases and controls); Euthyroid (10 and 5: P = 0.12), Hypothyroid (3 and 5: P = 0.38) and Hyperthyroid (7 and 9: P = 0.43). Of the hypothyroid patients 5 (cases 1 and controls 4: P = 0.13) required thyroxine replacement.
  
  
  CONCLUSIONS
  There was no statistical significant difference in the outcome of patients with dietary iodine restriction following I(131) therapy for Graves' disease.
authors.affiliation: Department of Endocrinology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Jubbin Jagan
authors.initials: JJ
authors.lastname: Jacob
authors.affiliation: Department of Biochemistry, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Charles
authors.initials: C
authors.lastname: Stephen
authors.affiliation: Department of Endocrinology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Paul
authors.affiliation: Department of Endocrinology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Nihal
authors.initials: N
authors.lastname: Thomas
authors.affiliation: Department of Nuclear Medicine, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Regi
authors.initials: R
authors.lastname: Oommen
authors.affiliation: Department of Endocrinology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: Mandalam S
authors.initials: MS
authors.lastname: Seshadri
keywords: Dietary iodine restriction; graves’ disease; radioactive iodine; urinary iodine/creatinine ratios