A single sleeping midnight cortisol has 100% sensitivity for the diagnosis of Cushing's syndrome
- 1 November 1995
- journal article
- research article
- Published by Wiley in Clinical Endocrinology
- Vol. 43 (5), 545-550
- https://doi.org/10.1111/j.1365-2265.1995.tb02918.x
Abstract
The diagnosis of Cushing's syndrome remains a major challenge in clinical endocrinology. Various screening tests are commonly used to support a biochemical diagnosis in the context of clinical suspicion. The aim of this study was to compare the sensitivity in the diagnosis of Cushing's syndrome of a single in-patient sleeping midnight cortisol to a standard 48-hour in-patient low-dose dexamethasone suppression test (LDDST) during the same admission.A retrospective analysis was performed on 150 patients investigated in our department between the years 1970 and 1994 with a confirmed diagnosis of Cushing's syndrome.One hundred and fifty patients with a diagnosis of Cushing's syndrome were analysed: 110 with Cushing's disease; 12 with tumours with ectopic ACTH secretion; 8 with ACTH dependent Cushing's syndrome of so far undetermined origin; 17 with cortisol secreting adrenal tumours; 3 with adrenocortical nodular hyperplasia. Twenty normal volunteers and nine patients with non-endocrine conditions were also investigated as controls.Plasma cortisol was measured by radioimmunoassay (RIA) in the 122 patients presenting after 1980, and by fluorimetry prior to this date.In all the control subjects the sleeping midnight cortisol was < 50 nmol/l, below the lowest standard of the routine in-house RIA. In every patient with Cushing's syndrome the sleeping midnight cortisol was detectable with a value greater than 50 nmol/l, with a range of 70-2000 nmol/l. In contrast, in three cases, all of whom had proven Cushing's disease on histology, there was uncharacteristic complete suppression of plasma cortisol to < 50 nmol/l following the LDDST.In this series of 150 cases, a single in-patient sleeping midnight cortisol above 50 nmol/l had a 100% sensitivity for the diagnosis of Cushing's syndrome, clearly different from normal subjects. In contrast, the low-dose dexamethasone suppression test had a sensitivity of 98% even when the drug was administered as an in-patient. We recommend that a low-dose dexamethasone suppression test should not be used alone for confirmation of Cushing's syndrome since it may miss 2% of cases.Keywords
This publication has 28 references indexed in Scilit:
- Investigation, management and therapeutic outcome in 12 cases of childhood and adolescent Cushing's syndromeClinical Endocrinology, 1995
- The limited ability of inferior petrosal sinus sampling with corticotropin-releasing hormone to distinguish Cushing's disease from pseudo-Cushing states or normal physiologyJournal of Clinical Endocrinology & Metabolism, 1993
- Corticotropin-releasing hormone stimulation following low-dose dexamethasone administration. A new test to distinguish Cushing's syndrome from pseudo-Cushing's statesJAMA, 1993
- Levels of GH binding activity, IGFBP‐1, insulin, blood glucose and cortisol in intensive care patientsClinical Endocrinology, 1991
- The diagnosis and differential diagnosis of Cushing's syndromeClinical Endocrinology, 1991
- Evidence for Two Subtypes of Cushing's Disease Based on the Analysis of Episodic Cortisol SecretionNew England Journal of Medicine, 1985
- Serum cortisol concentrations during low dose dexamethasone suppression test to screen for Cushing's syndrome.BMJ, 1984
- AN EVALUATION OF LABORATORY TESTS FOR THE DETECTION AND DIFFERENTIAL DIAGNOSIS OF CUSHING'S SYNDROMEClinical Endocrinology, 1977
- PITUITARY-ADRENAL FUNCTION IN SEVERE DEPRESSIVE ILLNESSThe Lancet, 1968
- A simple fluorimetric method for the estimation of free 11-hydroxycorticoids in human plasmaJournal of Clinical Pathology, 1962