Hemiagenesis of the thyroid gland.

Three patients with hemiagenesis of the typhoid gland are described. One was clinically euthyroid, whereas the other two were more unusual in that one had coincident Graves' disease with thyrotoxicosis, and one had primary myxodema. In all three cases diagnosis of hemiagenesis was established by the administration of thyroid-stimulating hormone (TSH). The literature on hemiagenetic thyroid glands with and without associated thyroid disease is reviewed. Although the anomaly is uncommon, awareness and recogniton of its existence may clarify an otherwise puzzling clinical thyroid evaluation, and thus possible avert an unnecessary surgical procedure.     

Recent developments in thyroid hormone metabolism: interpretation and significance of measurements of reverse T3, 3,3'T2, and thyroglobulin

The development of specific radioimmunoassays has allowed measurements of 3,3',5'-triiodothyronine (reverse T3), 3,3'-diiodothyronine (3,3'T2), and thyroglobulin to be performed in serum and in various biological fluids both in normal and in altered states of thyroidal economy. The physiology, kinetics, and metabolic actions of reverse T3, 3,3'T2 and thyroglobulin are reviewed. Presently, it appears that reverse T3 and 3,3'T2 measurements in amniotic fluid and cord serum may potentially be useful in diagnosing fetal or neonatal thyroid dysfunction, and serum thyroglobulin measurements appear to be important as a measure of the efficacy of treatment of patients with differentiated thyroid carcinoma.     

Barrett's esophagus: a review

Barrett's esophagus may be defined as a columnar epithelium-lined distal esophagus. As a frequently recognized complication of gastroesophageal reflux, Barrett's esophagus has become a diagnosis of general clinical concern. Factors governing the development of this complication in patients with gastroesophageal reflux are unknown but may be congenitally determined in part. When symptoms are present, they are due to the complications of reflux, such as esophagitis, stricture, ulcer, or bleeding. Barrett's esophagus may be suspected on the basis of results of a barium meal test, endoscopy, or isotope scanning. Iodine staining at endoscopy or manometrically guided biopsy helps to localize the abnormal mucosal segment. The diagnosis is proved by biopsy. The columnar epithelium of Barrett's esophagus has a malignant predisposition, and, once the diagnosis is made, periodic endoscopy, with biopsy and cytologic study, is indicated. The treatment of Barrett's esophagus is directed toward objective cessation of gastroesophageal reflux. In refractory cases, antireflux surgery improves symptoms and complications from reflux, but the columnar epithelium generally persists along with its malignant potential. It is not known whether effective antireflux treatment will lower the incidence of adenocarcinoma.     

The mechanism of the effect of acute stress on hexobarbital metabolism

The effect of acute stress (unilateral hind-leg ligation for 1 hr) on hepatic metabolism of hexobarbital (HB) was studied in the rat. A stress duration-response relationship was found for stress inhibition of HB metabolism. The hepatic microsomal protein content was not affected, but the hepatic microsomal cytochrome P-450 content was reduced approximately 45% by this stress treatment. Stress caused a twofold increase in plasma corticosterone level and had no effect on plasma corticosterone level of adrenalectomized rats. Hexobarbital metabolism was not affected by stress in adrenalectomized rats. Thus, the inhibition of hepatic HB metabolism by acute stress may be caused by the increased release of corticosterone induced by acute stress.