Establishing Reference Intervals for Serum and Salivary Cortisol in a Selected Population in Kano, Nigeria.

Serum cortisol has long been used in the assessment of disorders of the hypothalamic-pituitary-adrenal axis. The reference interval for cortisol in both serum and saliva depends on the analytical methodology and the population studied; hence, a locally derived population-based reference interval is recommended. To our knowledge, there are no studies on reference interval determination in the study area, raising concerns about the use of reference intervals established in European and North American populations. This work aimed to establish reference intervals for baseline serum and salivary cortisol levels among healthy adults in Kano, Nigeria, using methods available in our laboratory.