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Biomedical subjects

K Rootwelt

Publications and source records attributed to K Rootwelt.

At least 91 records · Page 5Linked to original sources
PubMed1981

Free thyroxine, thyroxine/TBG ratio and other in vitro tests of thyroid function evaluated by discriminant analysis.

T4, T3, TSH, FT4 (Corning method), TBG, T3U and a diversity of free thyroid hormone indices were determined in serum from 72 reference persons and 337 patients with either thyroid diseases, TBG abnormalities, non-thyroid illnesses, or medications known to affect the results of thyroid function tests. Ninety-six per cent were 20 years or older. None of the laboratory parameters showed significant age or sex dependence, whereas systemic illness and medications frequently influenced test results. Thus the mean values of all patient groups differed significantly from those of the reference group in two or more laboratory tests, and significantly from those of the reference group in two or more laboratory tests, and significant differences were detected in 73% of the total number of 209 paired comparisons of test results between reference and patient groups. As a single parameter, free thyroxine index was found to be a marginally more efficient thyroid function discriminator than FT4, which again was more efficient than the T4/TBG ratio. However, non of these parameters were included in the combinations of laboratory tests identified as optimum by discriminant analysis. The overall optimum test combination was T4, TSH and T3U, which had an efficiency for correct thyroid function reclassification better than 98% in the total material. T3 replaced TSH in distinguishing between hyperthyroidism and euthyroidism.

Adolescent↗
PubMed1978

Optimum laboratory test combinations for thyroid function studies, selected by discriminant analysis.

In 430 patients with a variety of thyroid disorders, linear discriminant analysis was used to select laboratory test combinations giving optimum diagnostic efficiency in thyroid function studies. Unexpectedly, TSH was found valuable in the diagnosis of hyperthyroidism and T3 in hypothyroidism. These test combinations were found optimal for the separation of euthyroidism/hyperthyroidism: T3, TSH and T4; euthyroidism/hypothyroidism: Combined free thyroid hormone index (FTI) and TSH; and hyperthyroidism/euthyroidism/hypothyroidism: T3, TSH, T4, FTI and T3U. The latter test combination had a total efficiency of 94%. Cholesterol, achilles reflex time, PBI and radioiodine uptake measurement contributed little to the discrimination.

Adolescent↗
PubMed1978

Effect of carbamazepine, phenytoin and phenobarbitone on serum levels of thyroid hormones and thyrotropin in humans.

Patients on long-term treatment with either of the stereochemically related antiepileptic drugs phenytoin (DPH) or carbamazepine (CBZ) had similar changes in serum thyroid hormone concentrations. T4, FT4, FT4 index, T3, FT3, FT3 index and rT3 were reduced, whereas T3U and TSH were not significantly different from the reference group levels. Long-term phenobarbitone treatment had no convincing effect on the investigated parameters when used alone, but possibly potentiated the effect of CBZ. In patients starting on CBZ, T4 fell to a stable 70% of the basal level after 1--2 weeks. T3 decreased transitorily to 85% of the basal level. TSH showed a complementary but somewhat delayed transitory increase. T3U and TBG did not change significantly. The effect of CBZ and DPH can be explained by interference with thyroid hormone binding to TBG combined with enzyme-induced increased metabolic clearance rate of thyroid hormones without homeostatic maintenance of premedication levels of FT4 and FT3. We suggest that the regulated factor maintaining euthyroidism in these patients is the total quantity of thyroid hormones being degraded in the tissues per unit time. We conclude that serum concentrations of FT4 and FT3 do not reflect thyroid status adequately under all circumstances.

Adult↗
PubMed1976

Infusion cisternography.

A source of error in cerebrospinal fluid (CSF) infusion tests is leakage at the dural puncture site. The addition of a bolus of radionuclide to the infusion fluid was helpful in detecting the existence of leakage as shown by increased infusion pressure in six of eight patients studied with and without scintigraphic evidence of leakage. Comparison of CSF dynamics in 26 patients studied by infusion cisternography and conventional cisternography showed similar patterns, suggesting no alteration of CSF dynamics by the artificial CSF infusion. Combining the two tests, therefore, resulted in simple identification of the leakage and saved the patient time and discomfort.

Cisterna Magna↗
PubMed1976

Use of 131I-toluidine blue in radionuclide imaging of enlarged parathyroid glands.

Parathyroid scintigraphy with 131I-labelled toluidine blue was performed in 40 patients, 30 of whom were operated for suspected hyperparathyroidism. Hyperplastic glands or adenomas could be localized by scintigraphy in 18 of 27 patients who proved to have hyperparathyroidism. The correlation between scintigraphy and operative finding was always correct when the parathyroids weighed more than 2 g. Scintigraphy was correctly negative in one, falsely negative in 6, and falsely positive in 5 of the operated patients. In a group of 10 unoperated patients, scintigraphy was positive in one of the 3 patients with suspected hyperparathyroidism, but negative in the others. Although 131I-toluidine blue is not ideal as a scintigraphic agent for the parathyroids, we are of the opinion that it represents an improvement compared with 75Se-selenomethionine.

Evaluation Studies as Topic↗
PubMed1975

Effects of dipyridamole and acetylsalicylic acid on platelet functions in patients with aortic ball-valve prostheses.

The effects of dipyridamole and ASA on platelet functions were studied in patients with aortic ball-valve prostheses. Before ingestion, platelet adhesiveness was markedly reduced and platelet survival time slightly, but insignificantly shortened. ASA prolonged the bleeding time, reduced collagen-induced platelet aggregation, and inhibited secondary aggregation initiated by adrenalin. Similar effects were obtained with 2 Gm. of ASA alone as with 1 Gm. daily in combination with 225 mg. of dipyridamole. Platelet adhesiveness remained low. Depyridamole alone, 375 mg. daily, did not influence any of these parameters. The mean platelet half-life was prolonged from 3.52 to 3.72 days by each drug and to 4 days by the combined treatment. None of the differences was, however, statistically significant. A clinical study with ASA has been started in a larger series of patients to evaluate the effect on arterial thromboembolism.

Aortic Valve↗
PubMed1975

A comparison between urography and radioisotope renography in the follow-up of surgery for hydronephrosis.

The result of surgical correction of hydronephrosis caused by chronic obstruction at the pyeloureteral junction has been evaluated clinically as well as by urography and body background substracted renography performed preoperatively and up to 65 months postoperatively. The average follow-up period was 24 months. Twenty-eight patients (29 kidneys) were operated. Clinically 24 patients were improved. Urography showed regress of hydronephrosis and/or improved urinary pelvic drainage in 22 patients, whereas kidney function is judged from renography was improved in only 8 patients. Improvement in all parameters was generally most marked during the first postoperative months. Renographic improvement was seen much more often when the contralateral (non-operated) kidney was abnormal. Thus, kidney function in terms of effective renal plasma flow is rather uninfluenced by hydronephrosis surgery if the contralateral kidney is normal, whereas clinical improvement in urinary drainage is regularly obtained. This improvement in drainage is poorly registered by renography. It is concluded that renography is an important complementary method to urography, but the method cannot replace the radiological methods in the follow-up of hydronephrosis surgery.

Adolescent↗
PubMed1975

The influence of fatty acids on serum thyroxine determination by competitive protein-binding radioassay.

Thyroxine concentration, determined by competitive protein-binding radioassay (T4(D)), increased in serum stored at 20 degrees C and 37 degrees C. The increase correlated well with the increase in nonesterified fatty acids (NEFA). In vitro addition of NEFA to serum and in vivo increase in NEFA induced by post-prandial heparin injection resulted in a proportional increase in T4(D) values. Protein-bound iodine and thyroxine concentration, as determined by radioimmunoassay, were not influenced by storage and changes in NEFA concentration. NEFA interfere with T4(D), leading to elevated results.

Binding, Competitive↗