The influencing factors before the analysis of cortisol

2023-11-23
Cortisol is regulated by the body's hypothalamic-pituitary-adrenal cortex through the axial HPA, and its secretion is regulated by biological rhythm humoral and neural regulation. Although most laboratories have been able to determine the serum cortisol content more accurately by using automatic biochemical instruments. However, since all the work links of the tested specimens before entering the laboratory are not monitored by the laboratory, the quality of specimen collection is unknown to the inspectors, and the quality of inspection cannot be guaranteed. In order to make the majority of medical personnel pay attention to the quality control before the laboratory analysis, understand the matters that need attention before the detection of cortisol, and effectively improve the quality of the measurement of cortisol. This paper focuses on various influencing factors before the analysis of cortisol, and discusses how to control and avoid the influence of these factors on the measurement of cortisol as much as possible. In the actual work process, the influencing factors before the analysis and measurement of cortisol can be summarized into four categories: physiological factors, pathological factors, external factors and human influence.



1 Physiological factors



1. Whether gender differences can be the root cause of the difference in cortisol levels secreted by males and females, the research conclusions of domestic and foreign scholars have not been unified.



2 Psychological states such as stress, anxiety and depression can promote the increase of cortisol secretion. The reason is that the changes in psychological states such as tension and fear generated during blood drawing are easy to cause the continuous activation of the HPA axis, resulting in increased cortisol secretion by the body, resulting in certain differences between the test results and the original cortisol level in the body of the patient.



4. Different exercise methods, intensity and time have different effects on cortisol secretion levels. The main reason is that exercise causes high energy consumption in the body, and requires a large amount of blood sugar and brain nerves to accelerate fat mobilization and decomposition through regulation



Protein provides energy for the body to support, and the process of high-energy metabolism in the body brought about by exercise can cause the excitation of the HPA axis, thus stimulating the adrenal gland to secrete more cortisol.



Pregnancy and childbirth Pregnancy can cause changes in the level of cortisol secretion in the female body. The reason is that during pregnancy, the labor burden caused by the placenta to the body can promote the release of adrenocorticotropin releasing hormone (CRH) and adrenocorticotropin (ACTH) to promote adrenal synthesis, resulting in increased secretion of cortisol. And this pathway is not regulated by hormonal feedback.



6 Genetic deletion and mutation of the cortisol synthetase gene can affect the level of cortisol secretion in the body. The main reason is that the human body has congenital defects or gene mutations in some enzymes of cortisol synthesis. After the DNA coding sequence of these genes is transcribed and translated by RNA, it cannot synthesize a kind of cortisol synthetase which can effectively promote the synthesis of cortisol. As a result, the serum cortisol level of patients with this disease is lower than that of normal people.



7 Age differences Serum cortisol levels may also vary among people at different ages. The reason is that with the growth of age, the functional decline of various organs and tissues of the human body leads to the weakening of bone repair function, resulting in the decline of osteoblast synthesis ability and the increase of osteoclast synthesis ability. Because osteoclasts have the ability to promote cortisol secretion, cortisol secretion levels increase with the increase of osteoclasts in older people.



Malnutrition Malnutrition can affect cortisol levels in the body. It is mainly due to insufficient intake or lack of food or nutrients, resulting in insufficient energy supply of the brain nerve, resulting in the dysfunction of the HP A axis, forcing the adrenal gland to secrete more cortisol, improve the body's ability to decompose its own fat and protein, and provide energy for the body to maintain normal metabolic activities.



Hunger increases cortisol levels in the body. It is mainly due to the body eating little or no food, the periodic peristaltic contraction after gastrointestinal drainage will form a hunger signal to stimulate the central nervous system of the brain, cause the excitation of the HPA axis, promote the synthesis and secretion of cortisol, strengthen the liver glycogen and fat catabolism, promote gluconogenesis, in order to ensure the body's glucose supply.



Obesity and weight loss Obesity has a certain impact on the level of cortisol secretion in the body. The reason is that too much adipose tissue accumulates in the brain, causing the cranial nerve to be compressed by the surrounding adipose tissue, prompting the cranial nerve to make corresponding regulatory instructions due to the stimulation of internal environmental restrictions. These instructions act on the hypothalamus, causing it to synthesize and release C-Rh and activate the HPA axis, resulting in increased secretion of cortisol by the adrenal gland to regulate the breakdown and distribution of fat in the body. In addition, when losing weight, eating less or taking diet drugs can cause the body to produce a certain stress response, resulting in HPA axis excitement, resulting in abnormal cortisol secretion.



11 Other factors There are other factors that can also affect cortisol secretion levels, such as blood concentration or dilution due to dehydration or water intoxication feeding stereoendurance lactating prostaglandin aging individual differences within individuals differences in premenstrual syndrome amperimenopausal flushing and stress effects of various surgeries, etc. To some extent, it can cause the high or low level of cortisol in the body.



2. Pathological Factors



1 Brain Trauma Brain trauma affects the level of cortisol secretion in the serum. The reason is that the brain injury can stimulate the paraventricular nucleus near the third ventricle of the hypothalamus to transmit the injury impulse signal to the dorso-medial nucleus, activate the neurons synthesizing C-RH, increase the synthesis and release of CRH, cause the excitation of the HPA axis, and lead to the increase of cortisol secreted by the adrenal gland to enhance the body's resistance. Maintain and restore internal environment stability.



2 Diabetes Mellitus patients with diabetes have abnormal cortisol synthesis and secretion in the adrenal cortex. The reason may be that the abnormal metabolic state of high glucose in the body environment of diabetic patients prompts the body to initiate the oxidative stress system, resulting in excessive production of highly active molecules such as reactive oxygen radicals and active nitrogen radicals in the body. Such molecules can not only directly oxidize and damage DNA, proteins, lipids and other substances, but also act as molecular signals to activate a variety of stress-sensitive signaling pathways in nerves, including the activation of the HPA axis, which increases cortisol secretion and participates in the regulation of metabolism in the body. Secondly, the highly active molecules produced by oxidative stress can directly damage the stress-sensitive hippocampus, leading to hippocampal degeneration, weakening the hippocampal inhibition of HPA axis, and eventually causing the plasma cortisol level to rise.



3 Tumor factors Neoplastic diseases affect the level of serum cortisol secretion. The reason is that the tumor cells with clonal hyperplasia can produce substances with ACTH or CRH activity, stimulate the pituitary and adrenal glands to secrete excessive cortisol, resulting in increased cortisol levels in the body.



4 Depression Depression can also cause changes in serum cortisol levels. The main reason is that depressed patients have low or defective functions of the serotonin receptor in the hypothalamus, which leads to the barrier between the serotonin neurotransmitter that can produce pleasant emotions and the corresponding receptor, so that patients are in a long-term state of depression, which can stimulate the functional excitement of the HPA axis. Increases cortisol production by the adrenal glands. In addition, the functional sensitivity of the central norepinephrine receptor in patients with depression is reduced, resulting in the hypothalamus is not regulated by the feedback of norepinephrine, resulting in the increase of hypothalamic desinhibitory secretion of C-RH and the increase of cortisol levels.



5 Liver disease Liver disease can also affect the level of serum cortisol. The reason is that most of the metabolism of cortisol is inactivated and degraded by binding with sulfuric acid or glucuronic acid in the liver, and then excreted by the kidney. Therefore, the occurrence of liver disease can lead to a decrease in the liver's ability to catabolize cortisol, resulting in changes in serum cortisol levels.



6 Hemodialysis Hemodialysis can cause changes in the body's cortisol concentration. The main reason is that hemodialysis can effectively remove cortisol and inflammatory factors in the blood of patients with severe trauma, avoid the stress response of brain nerves and large-scale inflammatory response of the body induced by inflammatory factors, effectively reduce the possibility of systemic inflammatory response of patients, and thus improve the change of cortisol secretion regulation in the human body environment. To maintain the normal operation of the body.



7 Other diseases In addition, when the patient has hyperadrenal cortex or atrophic pituitary tumor, systemic lupus erythematosus, visual impairment, rheumatoid arthritis and other diseases and in a state of near-death, it can also affect the synthesis and secretion of cortisol, resulting in serum



Cortisol levels rise or fall.



3. External influencing factors



1 Climate and temperature Cortisol secretion levels are affected by climate and temperature. The reason is that different climate and temperature conditions can stimulate the peripheral and central thermoreceptors of the body, and the thermoreceptors will convert this stimulus into signals to transmit to the central nervous system. After the integration and processing of the central nervous system, the signals will issue instructions from the central nervous system-target gland system, act on each target gland, and change the activity of each target gland. It also includes inhibiting or activating the HPA axis to change the level of cortisol secreted by the adrenal gland, which jointly participates in the process of adjusting heat production or heat dissipation of the body, so as to maintain the relative stability of body temperature and make the body adapt to changes in the external environment more quickly.



Changes in elevation also cause changes in cortisol levels in the body. The reason is that after the human body enters the plateau area from the plain area, the atmospheric oxygen partial pressure decreases rapidly, and the body is in the stress state of hypoxia at the plateau, which can rapidly activate the HPA system, promote the secretion of cortisol, accelerate the protein, lipolysis and glycogenogenesis to increase the blood sugar concentration and provide more energy for the body. It helps the body adapt to the environment of high altitude and low oxygen.



Occupational stress can be accepted and integrated by the central nervous system as a stress signal and transmitted to the hypothalamus. The hypothalamus receives stimulation signals and secretes more CRH, which is used by the pituitary to release ACTH to promote the synthesis of the adrenal cortex and release cortisol to increase the cortisol concentration in the body.



Smoking can cause increased cortisol secretion in the body, resulting in high test results. The reason is that nicotine components in cigarettes have similar activities to C RH, which can activate the pituitary to release ACTH and increase plasma cortisol.



5 Toxic substances in the environment Exposure to or inhalation of toxic substances in the environment causes abnormal cortisol secretion. The reason may be that after contact with or inhalation of toxic substances in the environment, it accumulates in the body to a certain extent, exceeding the body's autonomous clearance ability, resulting in functional damage to some tissues of the body, or even obstacles to physical activity. Therefore, when the accumulation of toxic substances exceeds the body's ability to clear, the adrenal endocrine function can be damaged, resulting in abnormal cortisol secretion.



Noise Noise can cause the body to produce higher levels of cortisol. The reason is that noise can stimulate the human brain, so that it is in a state of stress, causing the brain nerve sympathetic nerve excitation, activate the HPA axis, resulting in increased cortisol secretion.



7 Pyrogenicity Pyrogenicity can affect the level of cortisol secretion in the body. The reason is that after exogenous pyrogenicity substances enter the body, the body will synthesize various kinds of immune cells and immune cytokines due to stress response. These substances can be secreted or act as thermogenic signals on the body temperature regulating cells in the brain nerve center, so that they can send out thermogenic signals and be used in the hypothalamus. As a result, the HPA axis is excited, the adrenal gland secretes more cortisol, and eventually causes the body temperature to rise.



8 Alcoholism and alcohol withdrawal The retention of alcohol in the body can lead to abnormal cortisol secretion. The reason is overload drinking, which can cause too much alcohol to enter the brain with the blood because it can not be effectively metabolized by the liver, stimulate or destroy the neuron cell membrane, and promote the neuron cell to send out damage signals. After receiving such signals, the central nervous system issues regulatory instructions through integration and processing, activating various nervous stress system pathways (including the HPA axis), and promoting the adrenal gland to secrete more cortisol. In addition, due to the dependence of the drinker on alcohol, acute abstinence will also make the body feel uncomfortable and produce a stress response, which will cause the dysfunction of the HPA axis and lead to abnormal cortisol secretion.



9 Heterophil antibody When the concentration of cortisol is detected by the immunoassay, heterophil antibody affects the detection result. The reason is that the heterophil antibody can bind to the trapping antibody and the labeled antigen at the same time, forming an abnormal reaction complex, consuming the trapping antibody that can bind to the measured cortisol, resulting in the phenomenon of low false detection results. In addition, heterophil antibodies can also bind only to capture antibodies, occupying the position and space of cortisol to be measured, thus making the detection results high and variable



The different binding forms of the trophil antibody and the marker antibody in the reagent lead to different determination results.



10 Others are exposed to dark or strong light, too high or too low acid alkaline water environment or chest stimulation, breast surgery, lead poisoning, inhalation of carbon monoxide, electric shock treatment, seasonal changes and space travel and other factors, the body makes stress response to adapt to the environment, and the activity of nervous system excitation HPA axis increases. The final manifestation is abnormal cortisol secretion, and the measurement results appear high or low phenomenon.



4 Human influencing factors



1 Collection time Whether the collection time is correct or not can affect the result analysis of serum cortisol. The reason is that the secretion of cortisol shows an obvious circadian rhythm and changes in a pulse-like manner. The secretion peak is about the morning and then gradually decreases.



It reached its lowest level by midnight. Therefore, in order to facilitate analysis and comparison, it is recommended that patients come to take blood on an empty stomach in the morning.



2 Use of anticoagulants Improper use of anticoagulants can affect the analysis and determination of cortisol, because the use of plasma containing anticoagulants has a greater impact on the measurement of cortisol, while the direct use of serum has a smaller impact on the measurement of cortisol.



3 Specimen preservation and treatment Unreasonable preservation and treatment of specimens can also result in incomparable cortisol test results. The reason is that when the blood samples are centrifuged, the glass tube wall is brittle and hard, which can destroy the composition of the specimen during the centrifugation process, resulting in the change of the serum cortisol content. The flexibility of the plastic tube is very good, the damage to the tangible components of the specimen is small, the impact on the measurement results is not large, and the plastic tube is not easy to break when used in the specimen transport and automatic specimen handling process, and the safety is better, and it is easy to handle after use. In addition, specimens should be sent for examination immediately after collection, and should not be stored for a long time and repeatedly freeze-thaw, because the concentration or activity of cortisol in serum may be reduced if the specimen is kept in the isolated environment for too long, and the determination of cortisol in specimens with repeated freeze-thaw will be low.



4 Additive interference The misuse of additives can influence the choice of methodology for cortisol determination. The reason is that the reagents currently available for analysis and measurement of cortisol often contain additives associated with the detection method