Please respond using peer reviewed articles no greater 5 years
Explain the action of thyroid hormone and how this impacts the diagnosis. Your answer should contain the impact of the thyroid hormone on functions in the body.
Thyroid hormone (TH) is a jack of all trades hormone that plays a small, and sometimes major, role in a lot of different aspects of the human body. Some of these roles are bigger than others, for example, thyroid hormone is utilized with blood cells and proper muscle functions. TH also is needed for the metabolism of blood and the developmental integrity of the hair, nails, and skin. (Huether & McCance, 2019). This brings relevance to our case study as it is noted on her assessment that her skin is thickening and dry. Also, with the effects noted with blood and muscle function, can contribute to fatigue and generalized weakness. “Thyroid hormones have direct effect on blood parameters by stimulating erythrocytes precursors and indirectly by enhancing erythropoietin production.” (Ahmed & Mohammed, 2020, p. 52). As we remember from our work with anemia, a symptom can be fatigue. TH is responsible for the signally required for cells to metabolize fats, proteins, and glucose for energy and heat. (Huether & McCance, 2019). Our patient in our case study is known for having a cold intolerance, secondary to the failure of TH to effectively signal for the generation of heat to combat exterior temperature conditions. Our patient is considered to be obese by her body mass index (BMI). Patients suffering from hypothyroidism have an extremely difficult time losing weight because of the issues in metabolizing nutrients, decreased energy production, and reduction in muscle and blood function. My wife can tell the story of how she and her best friend were able to diagnose her best friend’s hypothyroidism. My wife was trying to get back into shape after our oldest son and her best friend was looking to lose her pregnancy sympathy weight, so they started a diet and exercise program together. Living next door to each other they ate together and exercised together daily. My wife was losing her baby weight and gaining muscle, while her best friend did not. So, her best friend increased her intensity and was even more restrictive on her meals, and still no weight loss or any evidence that she had been making an effort. She explained these things to her doctor, had a blood test, and was diagnosed with hypothyroidism. With her prescription for a synthetic thyroid hormone replacement, she has seen much improvement with her life, but it requires regular monitoring and regulating to maintain optimal functionality.
Another functionality of the mysteriously important TH is that on mood, cognition, and emotional state. “In clinical hypothyroidism, though reported prevalence is low, severity of mood and cognitive symptoms can be severe. Endocrine disorders such as hypothyroidism can mimic neuropsychiatric disorders.”(Ahmed & Mohammed, 2020, p. 79). Our case study patient exhibited loss of memory, slow speech, and she has an anxiety diagnosis. All of these things, again, contributed to the neurological effects of a deficiency in TH. “In overt hypothyroidism, affective and cognitive decline may be present. In subclinical hypothyroidism however, neuropsychiatric symptoms are typically milder, such as deficits in memory and executive function”(Puchalapalli & Mahmood, 2020, p. 83). Shirley’s neuro decline is most likely attributed to her hypothyroidism.
As Thyroid Stimulation Hormone (TSH) levels rise, explain how this impacts the negative-feedback mechanism in the body.
So, your TSH in rising. What kind of an impact can a patient expects from and elevated TSH? First, we need to discuss what is TSH, and why is it rising. Thyroid stimulation hormone is released from and created in the anterior pituitary gland. (Murphy et al., 2017b). It is released in response to stress, cold, or metabolic demand. TSH goes directly to the thyroid where thyroid hormone is to be released to combat these demands, but instead the doors are closed, and the lights are off. The thyroid is not open for business. So that explains the increase in TSH loitering around the blood stream. Ideally the TSH would bind with the thyroid receptors and the release of thyroid hormones would take place, which translates into an increase in T4 and T3 which would provide feedback into the negative feedback loop causing the paraventricular nucleus in the hypothalamus to get the signal needed to stop releasing TRH, that would stop the TRH from signally the anterior pituitary gland thyrotropes to stop releasing TSH. (Murphy et al., 2017b). Ideally. In this case, the signal is broken so the hypothalamus is still excreting TRH to the anterior pituitary which is still producing TSH. As the pituitary continually tries to signal the thyroid with TSH, it is working, and the added stress causes compensation in the form of enlargement. (Huether & McCance, 2019). While the thyrotropes in the anterior pituitary are pumping away the neighboring lactotropes get involved and are stimulated as well due to the increase in TRH.(Huether & McCance, 2019). Imagine you are a lactotrope cell driving on a multilane highway at the speed limit, and you start getting passed by a lot of other thyrotrope cars. The more this happens, you begin to think you should speed up too. Peer pressure and the excess TRH now have the lactotropes increasing prolactin excretion. I do not think Shirley, our case study patient, will notice the symptoms of this new development. Galactorrhea may sound like a cool science fiction television show, it is not.
What are the roles of Thyroxine (T4) and triiodothyronine (T3) in the body?
Now this is a huge question since thyroxine, also known as T4, and triiodothyronine, also known as T3, have multiple roles within the body. “Thyroxine plays a crucial role in heart and digestive function, metabolism, brain development, bone health, and muscle control. It affects almost all of the body’s systems, which means proper thyroxine levels are vital for health.”(Hormone Health Network, 2018, para. 2). The majority of what I have learned about the endocrine system and the functions of thyroid hormones I have absorbed from Zach Murphy and his team’s lecture on Endocrinology. Murphy et al., (2017a) explain the distinction between the two substances is that thyroxine is more prominent of the two, but T3 does most of the work in the active form. As soon as T4 enters a cell is met with five prime deiodinase that removes a specific iodine molecule from T4, converting it to active T3. Active T3 then has the cell increase production of ATPases that will use ATP to move sodium out of the cell and potassium into the cell. This cellular process results in the decrease in available ATP, which in response increases oxygen usage, increases metabolic rate, increases production of heat, and increases the number and size of cellular mitochondria. The type of body cell the thyroid hormones interact with determine specific and or additional roles. For example, the liver reaction involves stimulating glycogenolysis, gluconeogenesis, and the creation of LDL receptors. This increases glucose in the blood and the removal of LDL from the blood. In the heart the thyroid hormone process stimulates that creation of beta-1 adrenergic receptors. Beta-1 adrenergic receptors respond to epinephrine and norepinephrine increasing the contractility of heart, increasing heart rate, and blood pressure. In central nervous system (CNS) cells, the thyroid hormones stimulate the increase in dendrites, myelination, and synapses production. This improves the ability of the CNS to improve cognition, alertness, and motor response. This T4 and T3 combo is sounding better and better. In our skeletal system, the effect on the osteoclast and osteoblast cells is to maintain the balance of bone creation and bone absorption. The thyroid hormones also interact with the epistle plates of the bones to promote growth, but I think most of us are past that point in our lives. In the adipose cells, T4 transitioning to active T3 breaks up the triglycerides into fatty acid chains and glycerol. The production of glycerol is important as it is fuel for the liver in gluconeogenesis. (Murphy et al., 2017a). Who wants to save all their adipose tissue for a rainy day? No one in our modern society, so slicing and dicing adipose tissue is another positive function. To go full circle with my stories, my wife’s best friend had trouble losing weight because the limitations in available T4 and T3 prevented her from cleaving her adipose tissue for fuel, while my wife’s normal thyroid function was allowing her to slash and burn, like a tropical rainforest, through her adipose tissue. Murphy et al., (2017a) also explain that thyroid hormones primary function with muscles throughout the body is to maintain the balance of anabolism and catabolism, or the building and breakdown of muscles. The proper level of thyroid hormones is important due to this balancing act. The function of T4 and T3 on the skin is tied in with the increase in heat production. This stimulates the blood vessels under the skin to dilate to allow for heat to radiate from the body. This also causes the sweat glands to increase sensitivity to allow for any necessary perspiration. The gastrointestinal (GI) system is affected by T4 and T3 by regulating gastric secretions and gastric motility. Too little T4 and T3 and the patient experiences constipation from decreased secretions and gastric motility, like our case study patient Shirley. Too much T4 and T3 and the patient’s GI tract turns into a luge resulting in diarrhea. (Murphy et al., 2017a). Since T4 and T3 have such a diverse affect on the body, I could probably find additional roles, but I believe this is a functional overview of the affects of T4 and T3 thyroid hormones in the body.
Ahmed, S., & Mohammed, A. (2020). Effects of thyroid dysfunction on hematological parameters: Case controlled study. Annals of Medicine and Surgery, 57, 52–55. https://doi.org/10.1016/j.amsu.2020.07.008
Hormone Health Network. (2018). Thyroxine. https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/thyroxine
Huether, S., & McCance, K. (2019). Pathophysiology (8th ed.). https://digitalbookshelf.southuniversity.edu/books/9780323583473
Murphy, Z., Beach, R., Popovice, K., & Ninja Nerd Lectures. (2017a, June 19). Endocrinology | Target Organs of the Thyroid [Video]. YouTube. https://www.youtube.com/watch?v=PdBGkp0UaG0
Murphy, Z., Beach, R., Popovice, K., & Ninja Nerd Lectures. (2017b, May 1). Endocrinology | Thyroid Overview [Video]. YouTube. https://www.youtube.com/watch?v=5aq_rxTbtws
Puchalapalli, A., & Mahmood, A. (2020). Neuropsychiatric comorbidities in hypothyroidism: A systematic review. Neurology, Psychiatry and Brain Research, 37, 79–86. https://doi.org/10.1016/j.npbr.2020.06.005
Please respond using peer reviewed articles no greater 5 years