Low serum thyroxine due to anti-thyroxine antibody.

Low serum thyroxine due to anti-thyroxine antibody.

In one case of untreated Hashimoto's thyroiditis, the serum thyroxine (T4) value, obtained by radioimmunoassay (RIA) employing resin to separate bound and free T4, was significantly lower than that obtained by competitive protein binding analysis (CPBA). The discrepancy was found to be due to the presence of anti-thyroxine autoantibody in the serum. This phenomenon is considered to be of practi...

False elevation of serum thyroxine in myxoedema due to thyroxine-binding autoantibodies. A diagnostic pitfall.

A 29-year-old male Caucasian with no relevant family history presented with a history of constipation, increasing tiredness and a feeling of intense coldness. His performance at sport, notably rugby and cricket, had fallen off badly largely because of weakness and muscle stiffness. His hair was falling out and his skin had become very dry. The clinical diagnosis was of myxoedema. He had a past ...

Spuriously high concentration of serum free thyroxine due to anti-triiodothyronine antibodies.

Thyroxine-binding by Serum

The occurrence of hypercholesterolemia, lowered basal metabolic rate and depressed serum proteinbound iodine in the nephrotic syndrome has directed attention to the thyroid gland in this disorder. Although hypothyroidism has been suspected, these patients are usually considered, on clinical grounds, to be euthyroid, and they fail to respond in a specific manner to even large doses of thyroid ho...

Unforeseen effect of thyroxine binding globulin when using the microencapsulated antibody method to determine free thyroxine (FT4): misleading results due to circulating unsaturated thyroxine binding globulin.

The effect of varying concentrations (0-52 mg/l) of purified thyroxine binding globulin (TBG) on the microencapsulated antibody method for free thyroxine was investigated. The results demonstrated that the free thyroxine values were strongly influenced by the concentration of thyroxine binding globulin in the samples. The standard curve could no longer be distinguished at a concentration of pur...