Hyper-cortisolism or hypo-cortisolism associated with several disease conditions ◦ Cushing’s Disease ◦ Addison’s Disease ◦ Congenital Adrenal Hyperplasia ◦ Depression ◦ Thyroid Disease Cortisol is an objective marker of the stress response
Urine Blood (serum or plasma) Saliva Hair ◦ Pros and Cons for each
◦ Pros: Non-invasive 24-hr urine cortisol/creatinine ratio excellent diagnostic for disease states. Not influenced by diurnal rhythm. ◦ Cons Need a timed urine sample, so difficult to collect diurnal samples Labor intensive for patients; can’t be used in patients with renal failure or dialysis High rate of cross-reactivity (numerous excreted steroid metabolites in urine) Most urine assays pick up cortisol metabolites (95%); only 2-3 % free cortisol
Pros Can collect diurnal data or after stress exposure Best measure for diagnosing certain hyper-cortisol states (e.g., Cushing’s via dex suppression test) Cons Blood draw expectation may increase cortisol release Provide measurement of cortisol at a single point in time Major fraction bound to corticosteroid binding globulin (CBG) and albumin (only 2-3% free). CBG influenced by pregnancy, oral contraceptives, hyperthyroidism – so levels measured may be high, but not reflective of bioactive cortisol Methods for assaying serum free cortisol are time consuming, expensive and require advanced techniques (ultrafiltration, gel filtration, gold standard: equilibrium dialysis)
Pros ◦ Non-invasive – can collect from infants, children, patients with poor veins ◦ Avoids stress-induced rise in secretion (like with a blood draw) ◦ Can collect at home or in the wild: Do not need to freeze or keep refrigerated ◦ Can collect one time or diurnal data ◦ Provides measure of free cortisol – best indicator of active hormone ◦ Correlates well with serum levels across a 24-hour period r=.67 in healthy people; r=.73 in patients with Addison’s disease; and r=.61 in patients with Cushing’s) Cons ◦ Provides measurement of cortisol concentration at a single point in time ◦ Periodontal disease, eating, tooth brushing can affect levels ◦ Sample quantity may be low (e.g., dry mouth, impatient) ◦ Messy
Pros ◦ Biomarker of chronic stress ◦ Relatively non-invasive ◦ Only free cortisol represented ◦ Easily transported and stored - put in an envelope or vial & store at room temp for months to years ◦ Reflects cortisol levels over past months (Hair grows predictably about 1 cm/month) – 1 cm closest to skull reflects last month; 2 nd cm out reflects preceding month So may not need to take multiple samples to evaluate chronic stress and perhaps compare months with and without a stressor ◦ Not affected by hair color – but maybe by dying of hair ◦ Significantly correlated with self-reports of stress (Kalra, 2007; Van Uum, 2008) Cons ◦ No clinically relevant reference range established to date ◦ Exposure to exogenous steroids in lotions or creams may cause sample contamination ◦ Mechanism of incorporation of cortisol into hair not known– is it from blood? Exocrine or sebaceous sources?
Radioimmunoassay Immunoassay - most common but may be at risk of cross reactivity with steroids other than cortisol (problematic in critically ill patients and in urine samples) High pressure liquid chromatography (HPLC)/mass spectrometry
A single sample ◦ unreliable unless: Collected accurately at a specific time of day for all subjects or Collected accurately at a specific time of day related to known time of awakening Diurnal Rhythm ◦ Unreliable unless collected accurately at correct times of day
Diurnal Rhythm ◦ Usually collect between 3-6 samples over the course of 1-3 days to evaluate: Awakening level – considered a measure of allostatic load Awakening response (15-45 mins after awakening) – considered a measure of acute stress response. Then one or more collections across the day High in morning, then falls over the day, lowest late in the evening (Kudielka & Kirschbaum, 2003) If an individual or group deviate from that rhythm, indicates dysregulation
◦ Mathematically transforms multivariate data into a summary of the information (Fekedulegn et al., 2007). ◦ Reflects the total cortisol released during the day ◦ Provides information on the magnitude of the response
Must validate correct collection times ◦ Self-report ◦ Phone calls ◦ MEMs Caps (electronic monitoring)
Pregnant women ◦ Levels very high but maintain a diurnal rhythm ◦ Blood levels very high unless measure only free because CBG increases significantly blood = bound + free Infants and toddlers
Fekedulegn, D.B., Andrew, M.E., Burchfiel, C.M, et al. (2007). Area under the curve and other summary indicators of repeated waking cortisol measurements. Psychosomatic Medicine, 69, 651-659. Kalra, S., Einarson, A., Karaskov, T., Van Uums, S., & Koren, G., (2007). The relationship between stress and hair cortisol in healthy pregnant women. Clinical and Investigative Medicine, 30, E103-107. Kudielka, B.M., Kirschbaum, C. (2003). Awakening cortisol response are influenced by health status and awakening time but not by menstrual cycle phase. Psychoneuroendocrinology, 28, 35-47. Pruessner, J., C., Wolf, O.T., Hellhammer, D. H., et al. (1997). Free cortisol levels after awakening: a reliable biological marker for the assessment of adrenocortical activity. Life Science, 61, 2539-2549. Russell, E., Koren, G., Rieder, M., & Van Uum. (2012). Hair cortisol as a biological marker of chronic stress: current status, future directions and unanswered questions. Psychoneuroendocrinology, 37, 589-601.
Serum cortisol levels among individuals with TSH levels >2.0 uIU/L (N=31) were significantly higher than among those individuals with TSH levels ≤ 2.0 uIU/L (N=20) [13.83 ± 0.93 ug/dL vs. 8.66 ± 0.59 ug/dL, respectively, F(1,48)=14.24, p<0.0001]. Walter, Corwin, Ulbrecht, Demers, Bennett, Whetzel, & Klein (2012). Thyroid Research.
To change cortisol from ◦ Microgram to nanomolar; Microgram x 2.76