THYROID FUNCTIONS IN PATIENTS WITH RESPIRATORY FAILURE
Mohammed Abdel Ghffar Mohammed Abdel Rahman;
Abstract
The thyroid is a highly vascular, brownish-red gland located anteriorly in the lower neck, extending from the level of the fifth cervical vertebra down to the first thoracic. The gland varies from an H to a U shape and is formed by 2 elongated lateral lobes with superior and inferior poles connected by a median isthmus, with an average height of 12-15 mm, overlying the second to fourth tracheal rings. Occasionally, the isthmus is absent, and the gland exists as 2 distinct lobes (Gravante, 2007).
The thyroid gland produces L-thyroxine (T4) and L-triiodothyronine (T3), which regulate metabolic body processes, cellular respiration, total energy expenditure, growth and maturation of tissues, and turnover of hormones, substrates, and vitamins. Thyroperoxidase is synthesized within the endoplasmic reticulum of the thyrocyte and oxidizes iodine, thereby facilitating the formation of T3 and T4. T4 is the prohormone, broken down in the tissues to form T3 as needed. Release of the hormones into the bloodstream involves the negative feedback system of the hypothalamic-pituitary-thyroid axis. A low metabolic rate or a decrease in serum T3 and/or T4 levels signals the hypothalamus to secrete thyrotropin releasing hormone (TRH), which travels to the anterior pituitary gland and stimulates secretion of thyroid-stimulating hormone (TSH). Thyroxine-binding globulin (TBG) is the primary protein that binds to T3 and T4 in the plasma (United States Preventive Services Task Force, 2006).
Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In areas of adequate iodine intake, autoimmune thyroid disease (Hashimoto disease) is the most common cause of hypothyroidism; worldwide, iodine deficiency remains the foremost cause .
Hypothyroidism commonly manifests as a slowing in physical and mental
Summary
- 92 -
activity but may be asymptomatic. Symptoms and signs are subtle and
neither sensitive nor specific (Busko, 2013).
Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to the hypermetabolic condition of thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves disease), toxic multinodular goiter (Plummer disease), and toxic adenoma. Thyroid function tests for hyperthyroidism are as follows: Thyroid-stimulating hormone (TSH), Free thyroxine (FT4) or free thyroxine index, and Total triiodothyronine (T3( (Frost et al., 2004).
Respiratory failure is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, it may be classified as either hypoxemic or hypercapnic. Common causes of type I (hypoxemic) respiratory failure include: Chronic obstructive pulmonary disease (COPD), Pneumonia, Pulmonary edema, Asthma, Pulmonary embolism, … etc Common causes of type II (hypercapnic) respiratory failure include : COPD, Severe asthma, Drug overdose, Poisonings, … etc (Medscape Medical News, 2014).
The non
The thyroid gland produces L-thyroxine (T4) and L-triiodothyronine (T3), which regulate metabolic body processes, cellular respiration, total energy expenditure, growth and maturation of tissues, and turnover of hormones, substrates, and vitamins. Thyroperoxidase is synthesized within the endoplasmic reticulum of the thyrocyte and oxidizes iodine, thereby facilitating the formation of T3 and T4. T4 is the prohormone, broken down in the tissues to form T3 as needed. Release of the hormones into the bloodstream involves the negative feedback system of the hypothalamic-pituitary-thyroid axis. A low metabolic rate or a decrease in serum T3 and/or T4 levels signals the hypothalamus to secrete thyrotropin releasing hormone (TRH), which travels to the anterior pituitary gland and stimulates secretion of thyroid-stimulating hormone (TSH). Thyroxine-binding globulin (TBG) is the primary protein that binds to T3 and T4 in the plasma (United States Preventive Services Task Force, 2006).
Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In areas of adequate iodine intake, autoimmune thyroid disease (Hashimoto disease) is the most common cause of hypothyroidism; worldwide, iodine deficiency remains the foremost cause .
Hypothyroidism commonly manifests as a slowing in physical and mental
Summary
- 92 -
activity but may be asymptomatic. Symptoms and signs are subtle and
neither sensitive nor specific (Busko, 2013).
Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to the hypermetabolic condition of thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves disease), toxic multinodular goiter (Plummer disease), and toxic adenoma. Thyroid function tests for hyperthyroidism are as follows: Thyroid-stimulating hormone (TSH), Free thyroxine (FT4) or free thyroxine index, and Total triiodothyronine (T3( (Frost et al., 2004).
Respiratory failure is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, it may be classified as either hypoxemic or hypercapnic. Common causes of type I (hypoxemic) respiratory failure include: Chronic obstructive pulmonary disease (COPD), Pneumonia, Pulmonary edema, Asthma, Pulmonary embolism, … etc Common causes of type II (hypercapnic) respiratory failure include : COPD, Severe asthma, Drug overdose, Poisonings, … etc (Medscape Medical News, 2014).
The non
Other data
| Title | THYROID FUNCTIONS IN PATIENTS WITH RESPIRATORY FAILURE | Other Titles | وظائف الغدة الدرقية في مرضى الفشل التنفسي | Authors | Mohammed Abdel Ghffar Mohammed Abdel Rahman | Issue Date | 2014 |
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