ABSTRACT
OBJECTIVES: Recent guidelines recommend a diagnosis of adrenal insufficiency when a stimulated peak cortisol level falls below 500nmol/L. This may not be valid using a highly specific cortisol immunoassay or liquid chromatography-mass spectroscopy (LCMS/MS). We sought to determine the diagnostic threshold for adrenal insufficiency using a new and widely available, highly specific cortisol immunoassay. DESIGN: All patients having a dynamic test of adrenal reserve had results measured using the historical cortisol assay (Roche Cortisol) and the newer assay (Roche Cortisol II). MEASUREMENTS: Subjects were categorized according to the traditional assay (normal>500nmol/L) with clinical case adjudication where necessary. Results from Cortisol II assay were concomitantly measured along with cortisol levels measured by LCMS/MS. ROC curve analysis was performed to generate new diagnostic thresholds. RESULTS: The Roche Cortisol II compared favourably with measures by LCMS/MS, generating cortisol levels approximately 30% lower than the older immunoassay. Many normal subjects had peak cortisols as low as 300nmol/L with Cortisol II. The optimized diagnostic threshold for adrenal insufficiency was 350nmol/L with a sensitivity of 91% and specificity 97%. Use of the old diagnostic threshold with the Cortisol II assay would have inappropriately doubled the rate of patient-classification as adrenal insufficient. CONCLUSIONS: Transition to a more specific cortisol assay requires revision of diagnostic thresholds for dynamic tests of adrenal insufficiency. With the Roche Cortisol II assay, a cut-off of 350nmol/L should replace the traditional 500nmol/L although some healthy subjects may be very close to this level.
Subject(s)
Adrenal Insufficiency/blood , Adrenal Insufficiency/diagnosis , Clinical Laboratory Techniques/instrumentation , Clinical Laboratory Techniques/methods , Hydrocortisone/blood , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Immunoassay/instrumentation , Immunoassay/methods , Infant , Infant, Newborn , Male , Middle AgedABSTRACT
A 46-yr-old man presenting with biliary obstruction from an intrapancreatic tumor underwent pancreaticoduodenectomy. The pathology report showed the tumor to be an enteric duplication cyst. Diagnostic imaging features and operative management are discussed.
Subject(s)
Cholestasis/etiology , Duodenum/abnormalities , Pancreatic Cyst/complications , Humans , Male , Middle Aged , Pancreatic Cyst/diagnosis , Pancreatic Cyst/surgeryABSTRACT
Acute pyelonephritis developed in a 67-yr-old man after transrectal ultrasonographically guided biopsy of the prostate. The clinical presentation and results of excretory urography were nondiagnostic. Diagnosis was made by computed tomography, which was delayed 12 h after i.v. administration of contrast medium.
Subject(s)
Biopsy/adverse effects , Prostate/pathology , Pyelonephritis/diagnostic imaging , Pyelonephritis/etiology , Tomography, X-Ray Computed , Acute Disease , Aged , Biopsy/methods , Humans , Male , Prostate/diagnostic imaging , UltrasonographyABSTRACT
Interpretation of clinical laboratory results, aside from clinical considerations, is based on the probability of the result being within a given normal range. This probability is influenced by the degree of error inherent in the analytical method. It would be advantageous to assign a more definite probability to the result of the measurement by combining the error distribution of the result around the true value and the distribution of the healthy population that serves as a reference. Bayesian statistics permits the revision of this prior information into a single probability.
