Search

Screening newborns for congenital hypothyroidism (a condition of decreased activity of the thyroid gland, which is present at birth) can be performed to identify this condition. Early treatment may avoid the development of mental retardation. In 1987, recommended guidelines for newborn screening were established jointly by the American Academy of Pediatrics and the American Thyroid Association. At that time, an optional test was thyroid scintigraphy with technetium-123, a study of radioisotope uptake in specific body tissue. This test, although providing a more specific diagnosis, was not recommended for routine use because of a slight risk of radiation exposure. However, this position does not represent a maximum diagnostic effort, which should be made to obtain a specific diagnosis as early as possible, as the disease will require lifelong treatment. A classification of congenital primary hypothyroidism is proposed that clarifies the genetic and abnormal physiologic variations of this heterogeneous condition. The two main categories are dysgenetic hypothyroidism (abnormal thyroid gland formation), which includes athyrosis and ectopia (absence and abnormal location of the thyroid, respectively); and dysfunctional thyrotic hypothyroidism, which includes conditions of abnormal hormone production both with and without goiter, along with transient and undefined primary thyroid function abnormalities. Previously, it was thought that most cases of congenital hypothyroidism were due to anatomic malformation of the thyroid gland. However, increased use of scintigraphy has shown an increasing percentage of babies with hypothyroidism who have identifiable thyroid glands in the proper location. The category of dysfunctional thyrotic hypothyroidism is broad enough to include a variety of abnormalities that may be defined in the future. (Consumer Summary produced by Reliance Medical Information, Inc.)

• The free thyroxine index (FTI) was used in 2,704 adults to detect unsuspected thyroid dysfunction. Among 2,581 adults found to be clinically euthyroid without thyroid medication, 2,571 had a truly normal FTI (121 to 360) and ten had a falsely abnormal FTI (seven <121, three >360). Among 25 subjects with newly diagnosed thyroid dysfunction, there were eight hyperthyroid (prevalence, 0.31%) and 14 hypothyroid (prevalence, 0.50%) subjects. The sensitivity of the FTI was 1.0, and the specificity was 0.996. The predictive value of an abnormal FTI with a prevalence of 0.81% was 67%. The cost to find a new case averaged $127. The annual incidence of symptomatic hyperthyroidism was 0.05%; of hypothyroidism, about 0.08%. We conclude that the FTI is cost-effective for case finding in thyroid dysfunction.(Arch Intern Med 140:1045-1049, 1980)

Rapid scintiphotographic placental imaging using free 99mTc-pertechnetate ion was performed in 96 women, 82 of whom had third-trimester bleeding classified as “mild” or “moderate.” Results of localization were expressed as “not placenta previa,” “equivocal for previa,” or “placenta previa,” and these classifications included 82, 8, and 6 patients, respectively. There were no false-positive or false-negative localizations; placenta previa occurred only in the moderate-bleeder group; and 2 of the 6 patients with placenta previa were adolescent primigravidas. Fetal radioisotope exposure was minimal. Scintiphotography using 99mTc-pertechnetate eliminates confusion caused by active bleeding or bladder accumulation of isotope and permits more accurate localization than do other methods now in use.

Stool radioactive copper was decreased and urinary excretion increased after intravenous administration of cupric chloride 67Cu in eight homozygotes of Wilson's disease; cumulative excretion for 10 to 14 days was 3.7% to 13.2% of the dose; in six heterozygotes cumulative excretion was 7.8% to 23.8% of dose. Cumulative excretion in normal subjects was 24% to 40% of the dose. Two control subjects with hepatic failure excreted 10% and 14% of the dose respectively. The excretory data agreed well with the whole-body retention measurements in all subjects. Intermittent sampling of duodenal contents during the first few days after intravenous administration of radioactive copper suggested reduced biliary excretion as the proximate cause of decreased stool radioactive copper in the wilsonian subjects.

The whole-body turnover of cupric chloride (67Cu) was determined in 22 normal and other control subjects, 12 patients with cirrhosis of the liver, 21 known homozygotes of Wilson's disease, 9 presumptive heterozygotes (parents), and 15 family members (14 of whom were siblings), in a Chinese population (Taiwan) and an American population (San Francisco). The results obtained showed that whole-body retention of copper was prolonged in both homozygotes and heterozygotes of Wilson's disease, and in cirrhotic patients with ascites and/or hepatocellular failure. In the absence of clinical and laboratory evidence of hepatocellular insufficiency with or without ascites, prolonged whole-body turnover of copper may be used to identify the genetic defect of Wilson's disease.

Several letters to the editor are presented in response to articles in previous issues including "Fighting the Tide," by Dave Gardetta in the October 2010 issue, "The Well Runs Dry," by Mark Lacter in the October 2010 issue, and "Moren Maturity," by Steve Erickson in the October 2010 issue.