Biomedical subjects

H J Rusche

Publications and source records attributed to H J Rusche.

8 recordsLinked to original sources

PubMed1975

[Excessive peripheral conversion of thyroxine (T4) to triiodothyronine (T3) in the pathogenesis of T3-hyperthyroidism (author's transl)].

In a 41-year-old woman and a 3-year-old girl, both of them with T3-thyrotoxicosis, serum levels of total and free T4 and T3 were measured serially during anti-thyroid drug treatment. Attempts to substitute thyroxine during the antithyroid treatment had to be interrupted because the patients became hyperthyroid again with excessive increases in total and free serum T3, even when concentrations of total and free T4 were brought to subnormal levels. The increased conversion of administered thyroxine ceased later on and higher amounts of oral T4 were tolerated after one year of treatment. In both patients there was an extremely low serum T4/T3 ratio, differing in this respect significantly from six other patients with T3-thyrotoxicosis and 41 patients with "conventional" T3/T4-hyperthyroidism. It is concluded that, in patients with T3-thyrotoxicosis due to excessive peripheral T4 to T3 conversion, substitution during antithyroid drug treatment should be either with very low doses of thyroxine or with triiodothyronine in divided daily doses. In such cases the level of serum T3 represents the most reliable biochemical measurement for the control of treatment, serum T4 levels being irrelevant.

Adult↗

PubMed1975

Serum triiodothyronine 7-15 years after fractionated low dose radioiodine therapy of thyrotoxicosis.

In 189 of 334 patients, who had been treated with fractionated doses of radioiodine for Graves' disease 7-15 years ago, the serum concentrations of triiodothyronine have been estimated in additition to the following parameters: Protein bound 127-iodine (PB-127-I), free thyroxine index, cholesterol- and TSH-level in serum, tendon reflex time and clinical index according to Billewitz et al. (1969). In forty-one of the 189 sera the free T4 (AFT4) and free T3 (AFT3) concentrations were measured as well. The following hormonal and clinical patterns were observed: (1) Euthyroidism, with all parameters within the normal range in 148 patients (equals 78-4%). (2) Hypothyroidism with low serum T3, PBI, AFT4, AFT3 and elevated TSH six subjects (equals 3-2%). (3) Persistent hyperthyroidism with increased thyroid hormone concentrations and low TSH in seven cases (equals 3-7%). (4) In twenty-eight clinically euthyroid patients (equals 14-8%) TSH was elevated with normal PBI and AFT4. Twenty of these subjects had a low normal T3 and in nine the T3 was clearly in the hypothyroid range (40 plus or minus 12 mug/dl). (5) The constellation of normal T3, low T4 and elevated TSH, which has been frequently found after radioiodine therapy, has been seen in only moderate form in ten cases.

Adult↗

PubMed1975

Thyroid function and triiodothyronine and thyroxine kinetics in rabbits immunized with thyroid hormones.

Neck-uptake studies, thyroid scintiscans and triiodothyronine (T4)-kinetic studies were performed in normal rabbits and in animals producing antibodies against thyroid hormones. In immunized animals the radioiodide uptake and turnover were increased 3-fold and 6-17-fold, respectively. The thyroid glands were found to be enlarged scintigraphically and showed a denser tracer distribution pattern. T3 and T4 kinetic data were obtained from 5 rabbits immunized with T3 (ABT3), 4 immunized with T4 (ABT4) and from 5 controls. In T3 immunized animals total T3 in the serum rose from 86 to 59 000 ng/100 ml, in T4 immunized rabbits total T4 increased from 2.5 to 53.8 mug/100 ml. The fundamental principles of regulation were similar in both T3 and T4 immunized rabbits: There were enormous decreases in the total distribution spaces (TDS) as well as in the fractional turnover rates (k), resulting in markedly decreased metabolic clearance rates (MCR). The fall in T3-MCR was directly proportional to the T3 binding activity of the sera. However, striking differences between the respective alterations of T3 and T4 kinetic data were obtained in the immunized animals: T3-MCR fell about 70-fold in ABT3, whereas T4-MCR was diminished 15-fold in T4 immunized rabbits. In both groups of immunized animals T3-TDS decreased more than the T3 fractional turnover, whereas T4-TDS was less affected than k T4. The T3 production rates (PR) were increased 10-fold in ABT3 and 5-fold in ABT4, whereas the increases in T4-PR were of only moderate degree both in ABT3 and ABT4. Using presently available radiochemical methods in metabolic status of immunized rabbits could not be definitely assessed: "clinically" the animals were euthyroid. However, the dialyzable fraction in the serum of both T3 and T4 did not decrease proportionately to the enormous increase in total hormone concentration, so the free hormone concentrations were elevated over the normal. The results of the calculations of the cellular hormonal T3- and T4-clearance were more consistent with a euthyroid state: In ABT4 the cellular metabolism of both hormones was not different from the normal; in ABT3 a 1.7-fold increase in the cellular clearance of T3 was accompanied by a significant decrease of that in T4.

Animals↗

PubMed1974