Biochemistry

Reference Range

 Following visual inspection, results are reported as chylomicrons being present/not present.

Reference Range

Random cortisol

The reference range for cortisol (before 10am) is taken from the Alinity kit insert and is 102 – 535 nmol/L.

Short synacthen test

The current cut-off used for a short synacthen test (SST) is 450 nmol/L. This cut-off was derived from a paper in 2013 (El-Farhan et al¹) which studied the response to synacthen in healthy volunteers in Gen 2 immunoassays vs GC-MS . This study included the Abbott Architect platform (uses the same assay formulation as the Alinity analysers) which showed good correlation of the Gen 2 assay to GC-MS.  The bias of immunoassays to GC-MS was overall positive. The 2.5^th percentile of the geometric mean of post-ACTH stimulation cortisol concentrations for the Abbott assay were 430 nmol/L (Male) or 416 nmol/L (Female) compared to the cut-off of 420 nmol/L for a GC/MS method. It was therefore decided to keep the SST cut-off to 450 nmol/L.

(¹El Farhan et al (2013). Method-specific serum cortisol responses to the adrenocorticotrophin test: comparison of gas chromatography-mass spectrometry and five automated immunoassays. Clin Endocrinol 78(5): 673.)