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Biomedical subjects

W M McConahey

Publications and source records attributed to W M McConahey.

8 recordsLinked to original sources
PubMed1979

Electrocardiographic voltage changes during hyperthyroidism.

Electrocardiograms of 67 thyrotoxic patients were studied. Subsequent electrocardiograms during euthyroidism in 16 patients permitted an analysis of voltage changes. Decreases in voltages after radioiodine therapy were significant (P less than 0.01) for the P wave in lead, V1, R wave in leads II, AVF, V4, V5, and V6, maximal RS wave, and maximal R wave and were present in all but one patient. Criteria for left ventricular hypertrophy (sum of S wave in V1 plus R wave in V5 or V6 greater than 35 mm), present in 21% of patients, regressed in all five patients who had later electrocardiograms during euthyroidism. Left ventricular hypertrophy or high-voltage R waves in the absence of usual causes may suggest the presence of hyperthyroidism. The concept that cardiac voltage is determined in part by thyroid hormone is reviewed; this relationship may be the basis for increased voltage in hyperthyroidism as well as decreased voltage in hypothyroidism.

Adult↗
PubMed1978

Diagnosing and treating myxedema and myxedema coma.

Every patient with myxedema has hypothyroidism, but not every hypothyroid patient has myxedema. It often is possible to diagnose myxedema on clinical grounds alone. Characteristic symptoms are weakness, cold intolerance, mental and physical slowness, dry skin, typical facies, and hoarse voice. Results of the total serum thyroxine and free thyroxine index tests usually will confirm the diagnosis. L-thyroxine is the treatment of choice for myxedema, but it must be given to elderly patients with extreme caution. The transition from the hypothyroid to the euthyroid state brings about changes that put an added burden on the heart. The patient's clinical status and results of thyroid function tests determine the proper maintenance dose. Myxedema coma is rare but often fatal. It occurs most often in elderly women and may be mistaken for one of the chronic debilitating diseases common to this age group. Primary treatment is prompt administration of adequate doses of thyroid hormone--either l-throxine given intravenously of L-triiodothyronine given by nasogastric tube. It also is essential to identify and treat the condition precipitating the coma.

Coma↗
PubMed1978

Fluorescent thyroid scanning. A method based on stable iodine measurements.

Analysis by x-ray fluorescence allows in vitro determination of iodine content of the thyroid gland and a mapping of the regional distribution of iodine in the gland. The picture produced is similar to that of the conventional radioisotope thyroid scan. In 5 normal subjects and 70 patients with thyroid disease, the thyroid concentration of iodine varied between undetectable and 28 mg. With the exception of hypothyroid patients, who showed low thyroid levels of iodine, all patients showed iodine values overlapping the normal range. The fluorescent scan gave results similar to those of the isotope scan in most cases. Exceptions were noted in some hypothyroid patients, patients with flooded iodine pool, and patients receiving suppressive doses of exogenous thyroid hormone. Small cold nodules were best detected by the radionuclide scintigram. The value of the fluorescent scan is in its low radiation dose and in the possibility it affords of studying patients whose thyroid glands have reduced uptake of the radioactive tracer.

Americium↗
PubMed1975

Thyroid radioiodine uptakes and scans in euthyroid patients.

A substantial increase in the dietary iodide intake in many communities has caused a major increase in the total iodide pool in the body and a consequent decrease in the normal thyroid radioiodine uptake. Because of the pronounced regional variations in iodide supplementation of food, and because the effects of this additional dietary intake on radioiodine uptake are so large, a redefinition of the normal range of thyroid radioiodine uptake values in patients seen at this institution was thought to be indicated. The results of 6-hour and 24-hour thyroid radioiodine uptake studies in 44 euthyroid subjects, with scan data on the 20 who were studied with 123-I, are consistent with other reports indicating that the current normal thyroid radioiodine uptake values are lower than those accepted several years ago.

Adult↗