Carnegie Mellon University

24-hour Urinary Cortisol (PCS1)

Sample Collection

On the first day of quarantine (Day 0), subjects provided 24-hour urine samples which were used to assess levels of cortisol and catecholamines (see 24-Hour Urinary Catecholamines [PCS 1]).  Specimens were collected in dark urine collection bottles containing 2 g of sodium metabisulfate (preservative).  Subjects were instructed to begin collecting urine during their first morning void on Day 0, and to continue the collection until the same time on the following morning (Day 1).  Subjects were further instructed to record the date and time of their first and last collections on the label affixed to the exterior of the urine collection bottle.  Specimens were returned to study staff at the end of the collection period.

Sample Preparation

The total volume of each urine sample was measured and recorded.  After thorough stirring, 10-12 ml of urine was extracted from each sample, placed in a 15-ml plastic vial, and then stored at -70°C until analysis.

Assay Procedures

Cortisol assays were performed using a double antibody competitive radioimmunoassay at the Clinical Chemistry Laboratory of the University of Pittsburgh School of Medicine. The interassay coefficient of variation was 10%.


Ruder, H. J., Guy, R. L., Lipsett, M. B. (1972). A radioimmunoassay for cortisol in plasma and urine. The Journal of Clinical Endocrinology & Metabolism, 35, 219-224.