The effects of hormonal manipulation on gonadotropin, androgen, and estrogen concentrations in a patient with testicular feminization syndrome (TFS) were studied to clarify the feedback regulation of gonadotropins. Baseline serum LH concentrations were normal to high and FSH concentrations were normal despite markedly elevated plasma testosterone concentrations, implying the lack of a reciprocal control relationship, and fluoxymesterone administration failed to alter gonadotropin or androgenic steroid levels. Clomiphene administration resulted in a rise in both LH and androgen levels, while moderate doses of exogenous estrogens effected a diminution in testosterone but did not significantly alter the levels of gonadotropins. Following gonadectomy, these same doses of estrogens produced a dramatic fall in the very high postoperative levels of gonadotropins. These results suggest that gonadotropin regulation is mediated by estrogens and not directly by androgens in TFS.

Adult↗

PubMedDate not supplied

99mTc-PIPIDA cholescintigraphy in the diagnosis of gallbladder disease.

The efficacy of 99mTc cholescintigraphy in the diagnosis of gallbladder disease was studied in 116 patients. Sixty-one demonstrated gallbladder visualization (normal) and 55 had nonvisualization. In patients with acute abdominal pain, test sensitivity is 100%, specificity is 77%, and accuracy is 83% for the diagnosis of acute cholecystitis; no patient with gallbladder visualization had acute cholecystitis. Test sensitivity for any form of gallbladder disease is 66%, specificity is 82%, and accuracy is 71%; excluding patients with laboratory evidence of hepatobiliary disease, the predictability of acute or chronic cholecystitis increases to 100%. Cholescintigraphy demonstrated common bile duct patency in all eight post-cholecystectomy patients referred for evaluation of possible choledocholithiasis. Thus, gallbladder visualization with 99mTc-PIPIDA virtually excludes the diagnosis of acute cholecystitis, an abnormal test is a good predictor of gallbladder disease because of high specificity, and cholescintigraphy is extremely safe and simple to perform and may be used to demonstrate common bile duct patency.

Acute Disease↗

PubMedDate not supplied

Thyroid imaging.

Four modalities are being used to image the thyroid gland: (1) scintigraphy ("scanning"), employing one of several currently available radiopharmaceuticals, (2) ultrasound (US), (3) computed tomography (CT, "CAT" scan), and (4) magnetic resonance imaging (MRI). The first method, scintigraphy, provides an image of the spatial distribution of thyroid functional attributes, the nature of which are dependent on the interaction between the particular radiopharmaceutical employed and the tissue in question, whereas the latter three modalities provide an image of the spatial distribution of structural attributes such as the varying degrees of echogenicity of the tissues examined or the differential tissue attenuation of an x-ray beam, which permits visualization of the structures. A fifth modality, fluorescent thyroid scanning, in which fluorescence of the iodide within the thyroid gland is induced by low-dose external radiation and which gives an image of iodine distribution, is generally unavailable and only rarely used. For most patients, the combination of careful history, skilled physical examination, tests of thyroid function (and serum thyroglobulin and calcitonin for cancer evaluation), fine needle aspiration biopsy, and scintigraphy provide the most cost-effective means of evaluating the thyroid gland and its diseases. Of the four modalities currently used to image the thyroid gland--scintigraphy, ultrasound, computerized tomography, and magnetic resonance imaging--only scintigraphy has the widest application. It is employed to determine gland size, locate thyroid tissue, evaluate nodules and masses, determine the cause of a painful tender gland, differentiate various forms of goiter, detect differentiated thyroid carcinoma and gland remnants, assess suppressibility or stimulatability of the gland, and identify nonfunctioning cancers. Ultrasonography, computed tomography, and magnetic resonance imaging are not useful in differentiating between benign and malignant nodules, and their sensitivity in detecting impalpable nodules is not clinically useful, because nodules less than 1 to 1.5 cm in diameter are only rarely clinically significant. These modalities have limited utility in the evaluation of the thyroid gland: they are useful in sizing known lesions and for the detection of cervical lymphadenopathy in thyroid cancer cases.

Adult↗