Total and free thyroid hormone levels in chronic renal failure.

The levels of serum total thyroxine (TT4), triiodothyronine (TT3), free T3, (FT3) free T4 (FT4) and thyrotropin (TSH) were measured in 127 clinically euthyroid patients with varying grades of chronic renal failure (CRF); and 97 healthy individuals. They were grouped as: Group I containing 93 patients on conservative management; Group II containing 34 patients on regular dialysis therapy; and Group III (normals). Group I patients showed significant decrease in TT3, TT4 and FT3 levels (p less than 0.001) as compared to Group III, whereas FT4 and TSH values in group I were not significantly altered. TT3, TT4 and FT3 levels reduced as the severity of renal damage increased. Variations in TT3, TT4, FT3, FT4 and TSH levels in Group II patients were similar to those in Group I, except for a decrease in TSH levels (p less than 0.05) as compared to normals. Several thyroid function tests are abnormal in CRF patients, however, finding of normal FT4 and TSH levels would indicate functional euthyroid status.

Determination of free thyroxine in serum using column chromatography & radioimmunoassay.

A simple method for measurement of free thyroxine (FT4) levels in serum by adsorption chromatography and subsequent radioimmunoassay (RIA) is described. Assay sensitivity observed by this method was 1.2 pg/ml. Intra-assay variability was 11.2 per cent for FT4 concentrations of 7.9 pg/ml (n = 10), while interassay variability was 23.3, 9.7 and 12.9 per cent respectively for concentrations of 2.66, 12.06 and 23.96 pg/ml (n = 16). Serum FT4 concentration estimated by this method in 79 euthyroid patients was found to be 10.8 +/- 3.1 pg/ml. Values of FT4 obtained in hypothyroid and hyperthyroid patients were outside the normal range. FT4 values obtained by this method correlated well with the standard Liso-phase FT4 kit (r = 0.8) as well as free FT4 index (r = 0.93).

Detection of autoantibodies against 3,5,3'-triiodothyronine in a hyperthyroid patient (a case report).

A 35-year-old female patient was evaluated for thyroid function and was found to be hyperthyroid clinically and by laboratory tests. During the course of treatment with neomercazole, she developed a bizarre picture with consistently low T3 levels irrespective of her clinical thyroid status and other laboratory tests like serum T4 and TSH levels. The serum of the patient when analysed for the presence of autoantibodies was positive for those against T3. The presence of T3 autoantibodies was confirmed by other laboratory techniques like assessment of blank values in radioimmunoassay, binding of T3-125I to isolated gamma globulin and starch gel electrophoresis. Autoantibodies were found to be present only against T3 and not against. T4 The affinity constant of T3 antibodies was 4 x 10(9) lit. mol-1 as determined by Scatchard plot analysis while total binding capacity was 23 x 10(-11) mol/L.