The Importance of Homeostasis in Development on Hyperthyroidism

A female patient, 37 years old, came into clinic complaining mainly of difficulty sleeping, fatigue, frequent bowel movements and heart palpitations. As a physician, I needed to know more about the symptoms and signs the patient was experiencing in order to understand this syndrome. From what she expressed, there could be a myriad of syndromes. After asking various questions about her routine and other symptoms, I found out she was having heat intolerance, muscle weakness, hot flashes, sweating more than normal and problems with fertility. While I was doing a physical examination, I notice her breaths were less than 12 per minute, she was shaky and her hair was very thin. In particular, what was alarming was the bulging of her eyes. After examining her eyes, she was sensitive to light and mention she experienced double vision. After reviewing her family history, she has a mother and sister with a history of thyroid disease, especially Graves’ disease, and miscarriages. The purpose of this paper is to determine how homeostasis was disrupted in my patients body by explaining the importance of homeostasis stability in a healthy patient, looking at a possible diagnosis and   providing an explanation and definition of disease for the myriad of symptoms she came in with.

In order to find the reason why my patient was experiencing all these symptoms, I need to come back to the basics, as most answers are found in a disruption of homeostasis in the body. Homeostasis means an equilibrium between independent elements within the body. This equilibrium is essential for healthy functioning. The humans’ internal body temperature is a clear example of homeostasis. When a human is healthy, their bodies retain a temperature of 37.6 Celsius and the body has the ability to control its temperature by either making or releasing heat¹.   In a healthy individual, the maintenance of homeostasis usually involves negative feedback. A negative feedback loop is a type of self-regulating system¹ for the body. Let us look at our example of body temperature. In a negative feedback loop, high temperature will be detected by sensors, which we canal nerve cells. These cells have endings in your skin and brain and they send messages (temperature messages) to a temperature control center in your brain. The control center will access and process the information and activate what we call effectors. Effectors in this example will be sweat glands, who’s primarily job is to oppose the stimulus (high body temperature) by bringing the body temperature down¹.  Negative feedback helps maintain homeostasis because it counteracts the changes of the target values, such as temperature, and makes them come back to a normal set point. In my patient, an important aspect of maintaining hemostasis is temperature regulation as she expressed hot flashes and sweating more than normal.

In contrast, a positive negative loop will amplify the first stimulus; positive feedback is found in processes that need to be amplified in order to be completed, not when the stimulus needs to be maintained¹. Homeostasis usually involves negative feedback loops, but some biological systems use positive feedback to achieve homeostasis. A great example of positive feedback is childbirth². When the head of the baby pushes against the cervix, nerve impulses from the cervix are transmitted to the brain, and then the brain will stimulate the pituitary gland to secrete oxytocin². Oxytocin is then carried in the bloodstream to the uterus and it stimulates uterine contractions and pushes the baby toward the cervix². This positive feedback loop continues until the baby is born. Positive feedback helps maintain homeostasis because they are needed to push certain processes, such a childbirth into completion, hence maintaining an equilibrium in the body.

I believe my patient is having a problem with her negative feedback loops of hormones more than positive feedback; however, I will like to look at them both.  Looking back at my patients symptoms, signs and medical history it seems that she might have thyroid hormone regulation issues. Thyroid hormone secretion is regulated by a negative feedback loop¹. The thyroid hormones thyroxine and triodothyronine (T4 and T3) are located and secreted by the thyroid gland and affect various systems throughout the body³. In a normal negative feedback, sensory receptors (neurons) in the hypothalamus secrete thyroid-releasing hormone (TRH) in the control center, which fuels cells in the anterior pituitary to secrete thyroid-stimulating hormone (TSH), which will be the effector in this case³. TSH binds to receptors on epithelial cells in the thyroid gland, exciting synthesis and secretion of thyroid hormones, which will affect all cells in the body. When blood concentrations of thyroid hormones increase overhead a certain threshold, TRH-secreting neurons in the hypothalamus are repressed and stop secreting TRH³. In my patient, I believe the TSH hormone will be elevated as her symptoms such as unexplained weight loss and palpitations; especially the bulging eyes are a clear indicator of elevation of TSH hormone. In contrast, positive feedback mechanism will be rare in what my patient has, as I suspect she has elevated levels of TSH hormone and in a positive feedback loop, this will amplify it making the problem even worse. 

After going back to the basics, understanding how negative and positive feedback affect the body, looking at the symptoms, signs, physical examination, family history and results of her TSH blood⁴ test, I believe my patient has Hyperthyroidism. As hypothesized above, my patient homeostatic stability is out of balance. Her body is secreting higher levels of TSH hormone, specifically T4³ and this was proven correct by the high levels of T4 in her blood⁵. Her symptoms go hand in hand  with the profile of a person with Hyperthyroidism. She also has a family history of Graves’ disease in her family, specifically closely related relatives. In a combination with risk factors, such as a family history, particularly of Graves ’ disease, female sex and a myriad of symptoms that are related to hormone secretion problems, I can confident say this is Hyperthyroidism⁶.

This patient might have gotten a genetic marker for Graves ’ disease and in turn develop hyperthyroidism⁴. They are several treatments for hyperthyroidism. First, antithyroid medications to prevent the excess of T4 and T3 production. They are two types of medications in the United States Propylthiouracil and Methimazole⁶. Along with those medications beta blockers could also be prescribed as hypothyroidism can cause a dangerous increase in heart rate in some patients. Another treatment is surgery, which involves the surgical removal of the thyroid gland and it’s called thyroidectomy. The third and the best approach, in my opinion, for a 37 year old female is to start with radioactive iodine. Radioactive Iodine will be absorbed by her thyroid gland and cause the gland to shrink⁶. Her symptoms will go away with a couple of months. This treatment needs to be monitored in the first year to see if it works, if it does not anti-thyroid medications or surgery might be necessary⁴. When it comes to choosing a treatment, its important I understand the patient as a whole and see what are the best options for her. My patient is at a stage in her life that needs to have an easy treatment due to some socioeconomical issues she is experiencing. The final goal of treatment for her is to lower the amount of thyroid hormone that is produced and stablish a state of homeostasis in her body, so that she can have biological stability and function a healthy life.

In conclusion, a 35-year-old patient came into my practice displaying symptoms associated with hormone disturbances. She also had a very prominent family history of Graves’ disease and the major risk factors for a person with Hyperthyroidism.  After going back to basic and reviewing negative and positive feedback, it seemed that a higher secretion of T4 by her pituitary gland threw off my patient homeostatic balance. Radioactive Iodine was prescribed and a close follow up of one year in order to see if the treatment was effective. At the end of the day, the normal functioning of our bodies are simple and clear: homeostasis is the core of healthy functioning. Equilibrium and balance in our body along with balance in our emotional well-being is what I want my patients to have and be able to experience.

REFERENCES

1. VanPutte, C. “Seeley’s Anatomy & Physiology” Revised edition of: Seeley’s anatomy & physiology / Rod Seeley [and others]. 11th edition, c2014.
2. “Homeostasis” by OpenStax College, Biology, CC BY 4.0; Available from: http://cnx.org/contents/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8
3. Pirahanchi Y, Jialal I. Physiology, Thyroid Stimulating Hormone (TSH) [Updated 2019 Apr 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499850/
4. Nussey S, Whitehead S. Endocrinology: An Integrated Approach. Oxford: BIOS Scientific Publishers; 2001.Available from: https://www.ncbi.nlm.nih.gov/books/NBK22/
5. David E. Sadava, David M. Hillis, H. Craig Heller, and May Berenbaum, “Physiology, Homeostasis, and Temperature Regulation,” in Life: The Science of Biology, 9th ed. (Sunderland: Sinauer Associates, 2009), 847.
6. Mathew P, Rawla P. Hyperthyroidism. [Updated 2019 Mar 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537053/