Summary
- Dried urine is an alternative to liquid urine for measuring cortisol and its metabolites.
- 4-spot urine sampling is representative of a 24-hour urine collection.
- 4-spot urinary cortisol measures reflect the diurnal pattern of change in cortisol.
- Comprehensive profiling of cortisol is viable using both saliva plus dried urine samples.
Abstract
Background:
The primary aim of this study was to determine the utility of dried urine sampling in obtaining measures of cortisol and cortisol metabolites. Additional aims were to evaluate if a 4-spot dried urine collection is representative of a 24-hour urine collection and if expected diurnal cortisol patterns can be observed in samples from both urine and saliva.
Methods:
Data from individuals with cortisol measures available from both a 4-spot dried urine collection and a 24-hour urine collection (n = 28) were evaluated. Of these 28, 20 also had concurrent liquid and dried 24-hour urine measures. Consistency between these methods was evaluated using paired t-tests and intraclass correlation coefficients (ICCs). In addition, data from individuals with concurrent measures of both urinary and salivary cortisol (n = 68) were assessed for consistency in the diurnal pattern of change in cortisol.
Results:
Near ideal consistency was observed between liquid and dried urine for measures of total urine free cortisol, total urine cortisone, and total cortisol metabolites (n = 20; ICCs = 0.99, 0.97 and 0.96, respectively). Good to excellent consistency was observed between the 4-spot method and the 24-hour collection (n = 28; ICCs = 0.89, 0.95 and 0.92, respectively). In mixed model analysis, no difference was seen in the diurnal pattern of cortisol between salivary and urinary free cortisol (n = 68; P = 0.83).
Conclusions:
Dried urine is a viable alternative to liquid urine for the measurement of cortisol and cortisol metabolites. Additionally, if the 4 measures are added together, 4-spot urine collections can be representative of diurnal cortisol patterns commonly assessed using saliva and 24-hour urine collections.
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Newman, M., Curran, D. A., & Mayfield, B. P. (2020). Dried urine and salivary profiling for complete assessment of cortisol and cortisol metabolites. Journal of Clinical & Translational Endocrinology, 22, 100243.
