Puzzling biochemical thyroid profile in patients with multinodular goitre originating from a mild iodine deficient area in Tunisia.

Thirty Tunisian patients with a voluminous multinodular goiter with cold nodules and inhabiting a region of mild iodine deficiency, have been studied. The 131 I fixation by the thyroid, three hours after ingestion was significatively higher than in normal population. Fourty six per cent of the patients have stable iodine urine contents less or equal to 0.39 mumol/L. Three serum concentrations were paradoxically abnormal: thyrotropin (TSH), thyroglobulin (TG) and gammaglobulin concentrations. Fourty seven per cent of the serum thyrotropin (TSH) levels were less than the normal values though the serum total triiodotyronine (TT3), tetraiodotyronine (TT4), free triiodotyronine (FT3), free tetraiodotyronine (FT4), antithyroglobulin antibodies, total protein, triglycerides and cholesterol concentrations were normal. Serum thyroglobulin (TG) rates were elevated, ranged from 2 to 10,180 ng/ml and twenty five per cent of our patients showed levels greater than 500 ng/ml. The gammaglobulin levels were greater than normal in sixty eight per cent of our patients though only 10% of our patients manifest antithyroglobulin antibodies.