Biomarkers in Measuring Psychosocial Stress - Reserach Paper Example

According to Nater et al. 2013, Stress biomarkers that are assessed in the field of research are cortisol for hypothalamus axis activity, alpha-amylase for the autonomic nervous system, and pro-inflammatory cytokines for the immune system. Thus, this paper is focused on cortisol, alpha-amylase and pro-inflammatory cytokines in describing the measurement of work related psychosocial stress in working nurses population.

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Cortisol

When stress alters human body system, the hypothalamus is stimulated to secrete a hormone known as the Corticotrophin-releasing Hormone (CRH). CRH is responsible for triggering the anterior pituitary gland, which in turn secretes the adrenocorticotrophic hormone (ACTH). ACTH then initiates the adrenal cortex to release cortisol that is a glucocorticoids hormone (Rice, 2000). Cortisol metabolizes fats and proteins into glucose and elevates them into the bloodstream. This, in essence, is a process that is responsible for the release of energy needed in fight and flight response. Thus, for this reason, the human body cortisol is considered a vital biomarker for the determination of the level of stress in an individual (Inder, Dimeski, & Russell, 2012). Cortisol is released in response to both acute and chronic stress. Both serum and salivary cortisol are elevated during stress (Clements, 2012). Working nurses population have proven to have higher salivary cortisol levels during their working shifts as compared to their levels during their day off (Rocha et al., 2013). Salivary cortisol can concisely identify stress presence as it reflects either active free or corticotrophin binding globulin (CBG) cortisol (Clements, 2012). Nevertheless, salivary cortisol has a ten-fold lower concentration as compared to the total serum cortisol (Inder, Dimeski, & Russell. 2012). Furthermore. When used as a physiological biomarker for examining psychological stress with repeated measurements, salivary cortisol is more used as a biomarker of stress in most research settings (Inder, Dimeski, & Russell. 2012). Choosing salivary cortisol as a biomarker for psychosocial stress, there are multiple concerning confounders or variables that could be controlled, uncontrolled or saved to be as exclusion criteria in a specific study.

Controlled variables:

1) Timing and the law of initial value: reporting time during sampling is crucial as cortisol level has a diurnal rhythm which is characterized by the cortisol awakening response (CAR, a peak 30min after awakening in the morning) and a steady decrease over the day (Nater, Skoluda, and Strahler, 2013). Hodgson & Granger, 2013) strongly recommend that reporting time should be emphasized. Also due to diurnal cortisol rhythm, single samples would be insufficient to represent typical cortisol concentrations or reaction to a stressor (Clements, 2012). Thus, to get reliable results, sampling should be done immediately upon waking up, 30 minutes past waking, midday, and immediately before bed for two days at least (Hodgson, N. A., & Granger, D. A., 2013). Golden et al. (2011) found out that a diurnal cortisol curve generated from multiple samples collected from waking to midnight and a single 11 p.m. salivary cortisol sample had significantly higher reliability coefficients than the awakening cortisol, a single 8 a.m. cortisol, or cortisol concentration after dexamethasone suppression.

2) Methodology: regarding the methods used for collecting saliva, hydro cellulose microsponges were found to have higher volume recovery rates than cotton and result in comparable concentration to passive drool (Granger et al., 2007). According to Hodgson & Granger, 2013, sample quantity may be small (e.g., dry mouth, impatient) making it difficult to recover the sample for analysis. Also, if the material is left in the participants mouth long after it is fully saturated, the maximum absorbent capacity of a swab may bias estimates of salivary flow. Therefore, it is crucial to highlight that where a swab is placed in the mouth during collection has the potential to affect the measured levels or activity of salivary analytes secreted locally in the mouth. Hodgson, N. A., & Granger, D. A. (2013) recommend that swap should be placed under the front of the tongue for 2 to 3 minutes to get 25 to 50 ml per sample. Moreover, the collector of the sample should be able to understand written and oral instructions of the saliva collection procedure.

3) Ingested substances: eating, drinking, tooth brushing, and smoking change salivary pH or composition (Clements, 2012). Therefore, rinsing the mouth with water, and waiting 10 minutes before providing a specimen is recommended (Clements, 2012). Besides, participants should not eat or drink for 20 minutes before sample donation (Granger, Johnson, 2012). Medication such as diuretics, antipsychotics, antihistamines, barbiturates, hallucinogens, cannabis, and alcohol can indirectly affect some analytes by reducing salivary flow (Granger, Johnson, 2012). Moreover, intranasal, inhaled, or oral topical (e.g. teething gels) medications are particularly concerning. Those meds should be reported if taken within the last 48 hours (Granger, Johnson, 2012).

4) Age: because the population of interest is an adult population, the age-related difference is not an issue.

Uncontrolled variables, and limitations

1) Individual differences of secreting cortisol: lifestyle is an issue, for example, strenuous exercise performed can alter the results according to (Clements, 2012b). Research has shown that there is a rise in cortisol after intense exercise (Paccotti et al., 2005) but not typically after less intense exercise, and these rises differ by sex (Kudielka et al., 2009).

2) Psychological issues that could alter cortisol level in a stressful environment: coping, support or previous experiences among nurses in addition to the acute stressful event, or even external stressors could affect the cortisol level.

3) Gender is an uncontrollable variable unless if a study is aimed for the specific gender. According to (Clements, 2012), adult males have a much larger increase in cortisol concentration in response to stress than females do. Finally, it is known that at least some of the variability in cortisol concentrations across individuals is due to genetic individual differences (Clements, 2012b)

Exclusion variables

1) Pre-existing condition: participants who have endocrinal diseases or any condition that affect cortisol levels such as Addison, Cushing syndrome, fibromyalgia, chronic fatigue syndrome, hypertension, rheumatoid arthritis, asthma and mental illnesses (Clements, 2012).

2) Also, females who are pregnant, breastfeeding and on oral contraceptives are to be excluded (Clements, 2012). Lastly, periodontal disease can cause blood leakage, which might present higher level readings (Granger, Johnson, 2012).

Salivary Alpha-Amylase

Alpha-amylase is an enzyme that assists in breaking down polysaccharides. Secretion of alpha-amylase into saliva increases with sympathetic nervous system activation during the stress response independent of the flow of saliva (Rohleder et al. 2006). Salivary alpha-amylase is a useful biomarker that can be used in assessing human psychobiological and social, behavioral processes (Rashkova et al. 2012). Nevertheless, in a study that has been done on nursed using saliva to collect salivary alpha-amylase on a working day revealed that gender could be identified to have an impact on salivary alpha-amylase, with females having a more pronounced salivary alpha-amylase increase over the course of the day. Whereas depression, anxiety, work stress and burnout were not associated with salivary alpha-amylase, a small negative correlation between social difficulties, measured with the Chronic Stress Screening Scale, and salivary alpha-amylase could be identified (Wingenfeld et al. 2010).

Pro-inflammatory cytokines

Curtin et al. 2009 found out that psychological stress induces expression of the interleukin IL-10 and its homolog IL-19 via activation of b-adrenoceptors in an animal model, which indicate that stress enhances the production of immune-suppressive cytokines. Individuals suffering from chronic stress are often considered to be at a heightened risk of physical and mental health decline (Nater et al. 2013). No studies have been done on nurse population using pro-inflammatory cytokines to measure their occupational stress. However, a study by Berndt et al. has been done on competitive ballroom dancers who described themselves as being anxious and reported physical health complaints showed higher levels of interleukin (IL)-6.

Comparison of Biomarkers

There are many good biomarkers available to measure occupational stress among the adult nursing population. Alpha-Amylase, cortisol and pro-inflammatory cytokines are all valid and reliable markers of stress (Nater et al. 2013). Venipuncture to collect blood sample are more invasive than other methods used, due to this, this method is less desirable for this population. Cortisol and alpha-amylase can all be measured from saliva, which is less invasive and will most likely be easier to collect than urine or blood samples. Salivary Alpha-Amylase is most suitable for acute stressors whereas pro-inflammatory cytokines are most of the time saved for chronic psychosocial stress. However, cortisol, which is the most-studied stress hormone, has been effective in measuring acute and chronic psychosocial stress (Nater et al. 2013). Therefore, salivary cortisol will be the biomarker of choice in measuring work-related stress among the adult nursing population.

Table 1. Comparing collection of biomarkers, storage, measurement and reporting.

Collection Storage Measurement Reporting

Cortisol Saliva via absorbent materials (e.g., small cotton or foam swabs) in the mouth for 23 min or passive drool technique.

Capillary blood (50 microliters) (can be obtained via finger stick)

Urine (24 hour urine sample)

Peripheral venous blood (serum). Freeze saliva at -20 C to -80 C.

Store saliva at -20 C prior to analysis to loosen mucus Urine can last 24 hours at room temp without breakdown of cortisol

Dry blood spot until and store in dry place until ready for assay 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 Dependent on circadian rhythm, so time of collection should be reported.

Results reported in micrograms per deciliter (mcg/dL).

According to Mayo medical laboratories (2017), Reference Values for salivary cortisol are 100-750 ng/dL at 7 a.m.-9 a.m., <401 ng/dL at 3 p.m.-5 p.m. and <100 ng/dL at 11 p.m. through midnight. Hypercortisolism that could indicate Cushing syndrome, or presence of stressful events and hypocortisolism that might indicate adrenal insufficiency.

Alpha-Amylase Collected from saliva through passive drool, cotton swabs, or microsponge

Stored for 24 h at room temperature or 4 C , or 80C for longer storage immunoassay Report results in U/ml.

Pro-inflammatory cytokines C-reactive protein (CRP) Serum of 0.5 mL in gel tube Centrifuged within 2 hours of collection. Good for 14 days until assayed Particle-enhanced immunoturbidimetric assay

Clinically accepted value (<8 mg/L)

Information retrieved from Granger, D. A., Johnson, S. B., 2012; Mayo medical laboratories (2017);

References

Berndt, C., Strahler, J., Kirschbaum, C., & Rohleder, N. (2012). Lower stress system activity and higher peripheral inflammation in competitive ballroom dancers. Biological Psychology, 91(3), 357-364. http://dx.doi.org/10.1016/j.biopsycho...