Case Study, Chapter 41, Disorders of Endocrine Control of Growth and Metabolism
Bertha is a 71-year-old woman who takes daily medication for Hashimoto thyroiditis. Last winter, she developed pneumonia. Although she did her best to run errands for her husband, she got tired easily and needed to rest frequently. One day, after shoveling the snow outside, her husband came inside to find Bertha lying on the sofa covered in blankets. Her face appeared puffy and her eyelids hung. When he spoke to her, Bertha’s voice was hoarse and her words did not make sense to him. Her respirations were also shallow and slow. Suspecting low thyroid hormone levels were causing the signs, her husband called for an ambulance (Learning Objectives 6 and 7).
1. When testing for hypothyroidism, why is the free T4 level an important measurement? What would the TSH and T4 test results indicate in someone with primary hypothyroidism?
2. Using your knowledge of the function of thyroid hormone in the body, explain why Bertha’s respiratory rate was decreased? Why might pleural effusion be present in someone with hypothyroidism?
3. What factors in Bertha’s history leave her susceptible to myxedematous coma? What are the physiologic aspects involved in myxedematous coma?
Expert Solution Preview
Introduction:
In this case study, Bertha, a 71-year-old woman with Hashimoto thyroiditis, developed pneumonia and experienced various symptoms related to hypothyroidism. As a medical professor, I will address the following questions related to the management of hypothyroidism in Bertha:
1. When testing for hypothyroidism, why is the free T4 level an important measurement? What would the TSH and T4 test results indicate in someone with primary hypothyroidism?
2. Using your knowledge of the function of thyroid hormone in the body, explain why Bertha’s respiratory rate was decreased? Why might pleural effusion be present in someone with hypothyroidism?
3. What factors in Bertha’s history leave her susceptible to myxedematous coma? What are the physiologic aspects involved in myxedematous coma?
1. When testing for hypothyroidism, why is the free T4 level an important measurement? What would the TSH and T4 test results indicate in someone with primary hypothyroidism?
Free T4 level is important in testing for hypothyroidism because it is an indicator of active thyroid hormone levels available in the body. In primary hypothyroidism, where the thyroid gland is not producing enough thyroid hormones, the TSH (thyroid-stimulating hormone) level will be high, indicating the body’s attempt to stimulate the gland to produce more hormones. On the other hand, the T4 level will be low because the thyroid gland is not producing enough hormone. Therefore, the TSH and T4 level measurement will indicate primary hypothyroidism.
2. Using your knowledge of the function of thyroid hormone in the body, explain why Bertha’s respiratory rate was decreased? Why might pleural effusion be present in someone with hypothyroidism?
Thyroid hormone plays a crucial role in the regulation of metabolic rate and oxygen consumption in body tissues, including the respiratory system. Hypothyroidism leads to decreased metabolic rate, which may lead to respiratory depression and decreased respiratory rate. In addition, pleural effusion may occur in hypothyroidism because of increased capillary permeability and fluid accumulation, leading to compression of the lungs and reduced lung function.
3. What factors in Bertha’s history leave her susceptible to myxedematous coma? What are the physiologic aspects involved in myxedematous coma?
Bertha’s history of Hashimoto thyroiditis and pneumonia leaves her susceptible to myxedematous coma, which is a rare but life-threatening complication of severe untreated hypothyroidism. Myxedematous coma occurs due to decreased metabolic rate and body temperature, leading to impaired cognitive function, respiratory depression, and decreased cardiac output. The decreased metabolic rate causes accumulation of metabolic waste products, leading to myxedema, which is the non-pitting edema seen in hypothyroidism. The physiologic aspects involved in myxedematous coma include decreased thyroid hormone levels, reduced oxygen consumption, and decreased glucose utilization in the body.