Document Detail

Increased sensitivity to the inhibitory effect of excess iodide on thyroid function in patients with beta-thalassemia major and iron overload and the subsequent development of hypothyroidism.
MedLine Citation:
PMID:  11022172     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Patients with beta-thalassemia frequently develop primary hypothyroidism and other endocrine disorders due to iron overload. We studied whether administration of excess iodide to patients with apparently normal thyroid function could uncover an underlying thyroid disease. DESIGN AND METHODS: Twenty-five patients, 10 prepubertal (mean age 11+/-3 years) and 15 adults (mean age 23+/-5 years) with normal thyroid hormone and TSH levels, a normal response of TSH to TRH and negative thyroid peroxidase antibodies received 20mg iodide three times daily for three weeks, and thyroid hormone and TSH levels were measured weekly during, and for three weeks after, iodide administration and every 3 months thereafter for the next 5 years. RESULTS: During iodide administration there was a significant decrease in thyroid hormone concentrations which remained within normal levels, and a significant increase in TSH concentrations which in 14 out of 25 (56%) patients reached the hypothyroid level. Baseline TSH values were higher in those patients who developed subclinical hypothyroidism (2.31+/-0.71mU/l vs 1. 34+/-0.64mU/l, P=0.0016). Subclinical hypothyroidism developed in 70% of prepubertal and in 47% of adult patients. Serum ferritin was elevated in all patients. Nine of the fourteen patients (64.3%) who developed subclinical hypothyroidism during iodide administration developed hypothyroidism during the 5-year follow-up compared with only one of the eleven patients with a normal response to iodide (P=0.004). CONCLUSIONS: Patients with beta-thalassemia should not be exposed to excess iodide due to increased sensitivity to its inhibitory effects on thyroid function. The susceptible individuals frequently develop permanent hypothyroidism in the following years.
T Alexandrides; N Georgopoulos; S Yarmenitis; A G Vagenakis
Publication Detail:
Type:  Clinical Trial; Journal Article    
Journal Detail:
Title:  European journal of endocrinology / European Federation of Endocrine Societies     Volume:  143     ISSN:  0804-4643     ISO Abbreviation:  Eur. J. Endocrinol.     Publication Date:  2000 Sep 
Date Detail:
Created Date:  2000-10-26     Completed Date:  2000-10-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9423848     Medline TA:  Eur J Endocrinol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  319-25     Citation Subset:  IM    
Endocrine Division, Department of Medicine, University of Patras Medical School, Patras, Greece.
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MeSH Terms
Child, Preschool
Ferritins / blood
Follow-Up Studies
Hypothyroidism / etiology*,  ultrasonography
Iodides / adverse effects,  pharmacology*
Iron Overload / complications,  physiopathology*,  ultrasonography
Liver Function Tests
Thyroid Function Tests
Thyroid Gland / physiopathology*,  ultrasonography
Thyroid Hormones / blood
Thyrotropin / blood
beta-Thalassemia / complications,  physiopathology*,  ultrasonography
Reg. No./Substance:
0/Iodides; 0/Thyroid Hormones; 9002-71-5/Thyrotropin; 9007-73-2/Ferritins

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