Work

An oncocytic adrenal tumour in a patient with Birt‐Hogg‐Dubé syndrome

Year: 2013

Type: article

Abstract: Dear Editors,We read with interest the paper by Chitale et al. 1 and agree that the 60-minute sample is essential to the standard 250-mcg short synacthen test (SSST), in contrast to the low-dose short synacthen tests (LDSSTs), and welcome any research helping to clarify the optimal use of the short synacthen test in terms of dose, sampling times and diagnostic cut-offs.A recent survey of UK paediatric endocrinologists demonstrated 82% using a form of LDSST and 87% the SSST.All centres (N = 39) sampled at 0 and 30 minutes but 18% did not perform a 60-minute sample.There were a number of additional samples taken at different time points, with a mean of 3Á8 samples per SSST for all centres. 2 In keeping with national practice, our tertiary paediatric endocrinology service is predominantly performing LDSST; however, on analysis of the SSSTs undertaken between January 2011 and May 2012 (N = 20), we have found similar results to Chitale et al. in our paediatric cohort.Of the 20 tests analysed, the 60-minute cortisol value was higher than the 30-minute sample in 90%, on average 84Á1 nmol/l higher (SD 70Á6 nmol/l) supporting the use of a 60-minute sample to guard against false-positive results.Discrepant results, that is, those where the patient would be felt to have adrenal insufficiency based on the 30-minute cortisol value but not on the 60-minute result or vice versa depend on the cut-off value applied.Our national survey revealed that 54% of responding centres use 500 nmol/l and 44% 550 nmol/l. 2 Employing a cut-off of 500 nmol/l, 32% of our patients undergoing an SSST would have been misdiagnosed with adrenal insufficiency without the 60-minute sample and 10% using 550 nmol/l.In conjunction with our laboratory colleagues, we have recently revised our diagnostic cut-off to 450 nmol/l following the introduction of a new cortisol assay and welcome the authors' view that local reference ranges need to be determined rather than historically set values that may not reflect laboratory advances and variability.

Source: Clinical Endocrinology

DOI: 10.1111/cen.12292