Effective today, February 7, 2017, the University of Iowa Hospitals and Clinics core clinical chemistry laboratory will change the assay version for the serum/plasma cortisol assay (CORTISOL, Epic # LAB61).  The current assay will change to the next generation assay (Roche Diagnostics Cortisol II).

• We will be updating reference ranges to those in the package insert for the Cortisol II assay:

AM (7:00 – 10:00):  6.0 – 18.4 μg/dL
PM (15:00 – 17:00): 2.7 – 10.5 μg/dL

Reference ranges for cortisol display only in the footnote to the assay results given the variation in cortisol secretion across circadian rhythms.

• The new cortisol assay has much lower cross-reactivity to prednisone, prednisolone, and 6-methylprednisolone than the previous assay version. Thus, the results will more closely match endogenous cortisol concentrations in patients receiving these medications.

Questions should be directed to Matthew Krasowski, MD, PhD, medical director of the Clinical Chemistry Laboratory (384-9380, matthew-krasowski@uiowa.edu).