The diagnostic standard of preclinical Cushing's syndrome: evaluation of the dexamethasone suppression test using various cortisol kits.

Incidental discovery of an adrenal mass, the so-called adrenal incidentaloma, has been increasing due to the advances in non-invasive diagnostic imaging tools. The criteria of diagnosis for preclinical Cushing's syndrome (preCS) in Japan were made by Nawata et al. supported by the Ministry of Health and Welfare in 1995. The results of suppression of cortisol by dexamethasone (DEX) (plasma cortisol above 3 microg/dl after 1 mg of DEX and above 1 microg/dl after 8 mg of DEX) are essential for the diagnosis of preCS due to an adrenal adenoma. However, plasma cortisol levels after the two doses of DEX suppression tests were found to be discrepant and repeated DEX suppression tests sometimes yielded different results. Therefore, we examined the cortisol values of DEX suppression tests in patients with preCS using four different cortisol assay kits: Amerlex cortisol kit (AMA), SPAC-S cortisol kit (SPA), ADVIA-Centaur cortisol assay (ADV) and ECLusys 2010 cortisol assay (ECL). The diagnosis for preCS was done using the AMA kit. Correlation between the kits was good. However, cortisol levels measured by SPA, ADV and ECL were lower than those measured by AMA. In the 1 mg DEX test, the cortisol levels measured with the SPA, ADV and ECL kits were suppressed in 2 patients with preCS. With 8 mg of DEX, cortisol levels measured with the SPA and ADV kits were suppressed in 2 patients with preCS. The diagnosis of preCS is decided by the cortisol kit used, but the cortisol levels differ among the kits. It is suggested that the lack of the standardization of cortisol measurement is one of the causes of confusion in the diagnosis of preCS.

[Studies on the gonadal function in patients with anorexia nervosa using a highly sensitive radioimmunoassay kit for estradiol].

We measured serum estradiol (E2) using a highly sensitive radioimmunoassay kit in patients with anorexia nervosa (AN). It is possible to determine the ovarian function with hypogonadism in patients with AN whose levels of E2 were below 10 pg/ml. In patients with extremely low levels of BMI (less than 15 kg/m2), basal levels of E2, LH, FSH and IGF-I increased significantly with gain of body weight. Recovery of the hypothalamic-pituitary-ovarian function in AN patients were correlated with weight gain and nutritional status. The levels of IGF-I and E2 raised in advance of gonadotropins. Using highly sensitive assay of E2, we recognized the clinical usefulness for evaluation of the ovarian function in patients with AN in the course of treatment.