Hypothyroidism - Coursework on Medicine

Hypothyroidism by definition is a medical condition brought about by lack of production of enough hormones by the thyroid gland. Triiodothyronine, also known as T3 and thyroxine, also known as T4 are the hormones produced by the thyroid gland. They are important in maintaining the rate at which ones body uses up carbohydrates and fats. These hormones also influence the heart rate. Hypothyroidism is mostly present in women who are above the age of 60 (LeFevre, 2015). The deficiency in hormone production brings about a variation in the normal balance of chemical reactions in the body. In the early stages of the condition, symptoms are not present but if untreated, it results to various health problems.

There are various causes of hypothyroidism. One of the causes is autoimmune disease. This comes about when the immune system produces antibodies which attack the bodys tissues including the thyroid gland. The produced antibodies then affect the ability of the thyroid gland to produce hormones. Another cause of hypothyroidism is treatment used for hyperthyroidism. The medications are used to reduce the functioning of the thyroid but in some cases it may result to hypothyroidism. Radioactive iodine may also reduce functioning of the thyroid resulting to hypothyroidism. Removing a part of the thyroid through surgery also leads to reduced hormone production resulting to hypothyroidism. Some medication could also result to hypothyroidism. An example of such is lithium.

Hypothyroidsm may also be a congenital disease. This occurs when a baby is born without the thyroid gland or when the thyroid gland doesnt develop normally. A rare cause of hypothyroidism is when the pituitary gland does not produce enough thyroid stimulating hormone commonly due to benign tumor. Some women may also develop postpartum hypothyroidism and this increases the risk of preeclampsia, may cause a miscarriage or even affect the fetus. Taking in too much salt may also cause hypothyroidism. Diagnosis of hypothyroidism is done through laboratory testing (Pearce, 2015). An increase in the levels of TSH is an indicator that the patient is suffering from hypothroidism. In some cases, there may be a mild elevation of creatine kinase in the bloodstream. The levels of cholesterol are also elevated in patients with hypothyroidism.

The thyroid gland mainly secrets thyroxine into the blood which is then converted to triiodothyronine by iodothyronine deiodinase in the liver and kidneys. The T3 binds to the receptor then stimulates the production of various proteins. The hormone also binds to integrin located in the cell membrane and stimulates sodium-hydrogen antiporter. T3 is the active form of T4. The thyroid hormones are important in: regulating the metabolic rate of the body, maintaining bones, regulating the heart rate and also muscle control.

The thyroid gland is regulated by the pituitary gland which produces the thyroid stimulating hormone. The pituitary is in turn regulated by the through a negative feedback mechanism and by the hypothalamus. The hypothalamus works by releasing a hormone known as thyrotropin releasing hormone which sends a signal to the thyroid gland to release T3 and T4 (Ferri, Fred, 2015). If any disruptions occur in this cycle, the person suffers from hypothyroidism. If there happens to be a decreased amount of thyroid hormone in circulation, the release of thyroid stimulating hormone will be increased. In contrast, if the circulating thyroid hormone is in excess, the levels of thyroid stimulating hormone will be reduced. In patients suffering from hypothyroidism, there is a decrease in the level of thyroid hormones in circulation.

There is no classic symptom of hypothyroidism. However, the general symptoms that patients present with are:

Hoarse voice

Fatigue. This is because the thyroid hormone controls a balance of energy in the body. Therefore it influences a persons activity. Patients with hypothyroidism feel tired constantly and sleepier than usual.

Abnormal sensation

Feeling cold. This is due to the decreased metabolic rate which would otherwise result to burning of more calories hence heat production. Low thyroid hormone levels also turns down the thermostat of brown fat.

Shortness of breath

Muscle pain. Hypothyroidism results to a switch to catabolism and the body breaks down muscles for energy which is a painful process and also causes decreased muscle strength. The muscle pain is usually after a strenuous activity.

Poor memory and attentiveness

Weight increase. This is due to the fact that the thyroid hormones are responsible for regulating metabolic rate. In hypothyroidism, there is a decreased metabolic rate which results to storage of more calories as fat.

In females, menstrual irregularities

The main signs of hypothyroidism include:

Cold extremities

Irregular menstrual cycle. Most patients suffering from hypothyroidism experience heavy bleeding. This is brought about by the disruption in hormones that control the cycle. The thyroid hormones als control the uterus and the ovarie.

Inflammation of the limbs

Constipation. Hypothyroidism causes a reduction in the bowel movement which results to constipation.

Dry skin. The skin cells have a fast turn over. They are therefore more prone to loosing signals of growth from the thyroid hormones and they take longer to shed and for new ones to grow. This results to dry skin.

Reduced pulse rate

Myxedema. This is commonly caused by hypothyroidism due to autoimmune disease.

Delayed repose of muscle reflexes

Hair loss. This is because hair follicles have a quick turn over and are therefore very sensitive to a decrease in the level of thyroid hormones. When the level of the hormone decreases, the cells stop regenerating. This will result to loss of hair.

Carpal tunnel syndrome

A major characteristic sign of the disease is having a delayed relaxation which occurs when the patient is tested on the ankle jerk reflex. It determines the severity of the hormone decrease. From the diagnosis made on the patient, she is most likely suffering from hypothyroidism. This is evident from the presenting symptoms of: menstrual irregularities, weight gain, fatigue and muscle aches. On physical examination, the patient was seen to have enlarged thyroid lobes which had a firm consistency. The patient presented with a cold and dry skin that was rough and edema around the ankles. The lab diagnosis made on the patient showed increased levels of thyroglobulin due to thyrotoxicosis (Dons, Robert, Frank & Wians, 2014). The elevated level of thyroid stimulating hormone is due to lack of a negative feedback inhibition.

Hashimotos thyroiditis is an autoimmune disorder that leads to destruction of the thyroid gland. The disease is associated with polymorphism of Cytotoxic T-lymphocyte Antigen gene. Hashimotos disease also has a strong genetic component and the chances are more in people having chromosomal disorders. In some patients suffering from Hashimotos disease, the thyroid gland becomes large and lobulated and in others, the thyroid becomes nonpalpable. The thyroid enlargement is as a result of lymphocytic infiltration (Longo, Fauci, Kasper, Hauser, Jameson, Loscalzo, 2014). The antibodies work against thyroid peroxidase and thyroglobulin resulting to continuous destruction of the follicles located in the thyroid gland. Hashimotos disease can be diagnosed by detecting these antibodies in blood as well as detecting T lymphocytes in the thyroid tissue.

From the patients diagnosis, the patient presents with some symptoms of Hashimoto thyroiditis which include: Constantly getting tired, muscle pain, increase in weight, constipation and irregular menstruation (Vissenberg, van den Boogaard, van Wely, 2013). Treatment of hypothyroidism is a lifelong therapy. Levothyroxine sodium is the preferred form of treatment for the patient. This is because it is stable hence requires once daily dosing. T4 is naturally converted to T3 in the blood. Being an adult, the patient will require a lower dose than children of approximately 150 micrograms (Persani, L (September 2012). The T4 should ideally be taken half an hour before eating in the morning. The patient should also be advised to avoid medications that contain iron because they will obstruct the absorption of T4. Some other drugs which reduce the effectiveness of the levothryroxine are: Proton pump inhibitors, statins and oestrogens. The patient should also be advised to avoid calcium containing products, antacids and bile acid sequestrants since they prevent the absorption of levothyroxine. The drugs which increase the clearance of levothyroxine are: barbiturates, antiepileptics such as phenytoin and antibiotics such as rifampicin. Therefore these drugs need to be taken separately from levothyroxine. The levothyroxine takes about 10 days to be absorbed fully so patients improvement may take weeks.

The patient should then be monitored at intervals of six weeks, checking for the levels of thyroid stimulating hormone until she becomes stable (Garber, Cobin, Gharib, Hennessey, Klein, Mechanick, Pessah-Pollack, Singer, 2012). This will be important in maintaining the levels within normal limit because an excess of the thyroid medication could result to heart palpitations. Supplementation of vitamin D may be necessary to increases the levels.

References

Chakera, A.J., Pearce, S.H., Vaidya, B. (2012). "Treatment for primary hypothyroidism: current approaches and future possibilities". Drug Design, Development and Therapy

Dons, Robert, F. Jr, Frank, H. Wians (2014). Endocrine and metabolic disorders clinical lab testing manual (4th ed.).

Escobar-Morreale, HF; Botella-Carretero, JI; Escobar del Rey, F; Morreale de Escobar, G (2013). "Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine". Journal of Clinical Endocrinology and Metabolism

Ferri, Fred F. (2015). Ferri's differential diagnosis A practical guide to the differential diagnosis of symptoms, signs, and clinical disorders.

Garber, J.R., Cobin, R.H., Gharib, H., Hennessey, J.V., Klein, I., Mechanick, J.I., Pessah-Pollack, R. & Singer, P.A; et al. (December 2012). "Clinical Practice Guidelines for Hypothyroidism in Adults"

LeFevre, M.L. (2015). "Screening for Thyroid Dysfunction: U.S. Preventive Services Task Force Recommendation Statement"

Longo, D.L., Fauci, A.S., Kasper, D.L., Hauser, S.L., Jameson, J.L. & Loscalzo, J. (2014). Disorders of the thyroid gland". Harrison's Principles of Internal Medicine.

Pearce, E.N. (2015). "Update in lipid alterations in subclinical hypothyroidism". The Journal of Clinical Endocrinology and Metabolism.

Persani, L. (September 2012). "Clinical review: Central hypothyroidism: pathogenic, diagnostic, and therapeutic challenges". The Journal of Clinical Endocrinology and Metabolism

Stagnaro-Green, A; Abalovich, M; Alexander, E; Azizi, F; Mestman, J; Negro, R; Nixon, A; Pearce, E.N., Soldin, O.P., Sullivan, S., Wiersinga, W., American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum (2013). "Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum". CS1 maint: Multiple names: authors list (link)

Vissenberg, R., Van den Boogaard, E., Van Wely, M. et al. (2013). "Treatment of thyroid disorders before conception and in early pregnancy: a systematic review". Human Reproduction Update (Review).