Thyroid status and the levels of thyroid auto-antibodies in the sera of hyperthyroid and goitrous subjects.
OBJECTIVE
To determine the prevalence of thyroid auto-antibodies in specimens sent to Parirenyatwa hospital laboratory for thyroid function testing and to compare the thyroid status of these patients with that of apparently healthy subjects.


METHODS
Cross sectional study.


METHODS
Immunology and radio-immunoassay laboratories, Parirenyatwa hospital, Department of Chemical Pathology, and Blood Transfusion Services, Harare.


METHODS
212 blood samples submitted for thyroid function testing and 230 blood samples from apparently healthy blood donors.


METHODS
Serum concentrations of free triiodothyronine (FT3), thyroxine (FT4), thyrotropin (TSH), and thyroid auto-antibodies; anti microsomal (M Ab) and antithyroglobulin (Ag Ab) antibodies.


RESULTS
The hyperthyroid subjects had median serum TSH level of 0.027 mIU/L (Q1 = 0.006, Q3 = 0.052), median serum FT3 level of 15.895 pmol/L (Q1 = 10.563; Q3 = 30.111), and a median serum FT4 level of 45.513 pmol/L (Q1 = 30.256; Q3 = 63.910). The goitrous subjects had median serum TSH level of 0.390 mIU/L (Q1 = 0.157; Q3 = 0.745). The blood donor group had median TSH value of 0.724 mIU/L (Q1 = 0.471; Q3 = 1.170). (Normal ranges: TSH = 0.167 to 2.80) Amerlite TSH-30 diagnostic kit; FT3 = 3.4 to 7.2 pmol/L; FT4 = 11 to 24 pmol/L) Amelex-MAB diagnostic kits) Thirty nine percent of the hyperthyroid subjects had either positive M Ab or Tg Ab or both. None of the goitrous subjects and the blood donors tested positive for neither M Ab, nor Tg Ab. No significant difference was found between the blood donors and the goitrous subjects for serum FT4 (P = 0.51). However, significant differences were found between the goitrous, the blood donor and the hyperthyroid groups with regards to serum TSH, serum FT4, and serum FT3 levels (p = 0.001).


CONCLUSIONS
Our findings indicate that the occurrence of thyroid auto-antibodies among the blood donors and the goitrous population was uncommon, but high in the hyperthyroid subjects. The increase of iodine intake through iodine prophylaxis could have had the side effects of iodine induced hyperthyroidism.
Chinyanga
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EA
Department of Chemical Pathology, Medical School, Harare, Zimbabwe.
Benni
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A
Siziya
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S
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001782:Blood Donors; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D006042:Goiter / Q000097:blood* / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood* / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*; D008875:Middle Aged; D015995:Prevalence; D011863:Radioimmunoassay; D013960:Thyroid Function Tests; D013967:Thyroiditis, Autoimmune / Q000150:complications; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D015030:Zimbabwe / Q000453:epidemiology
D001323:Autoantibodies; C006606:anti-thyroglobulin; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine