THYROID GLAND Chloe Benner and Michelle Olson

LOCATION Situated in the anterior part of the neck “Adams’ apple” Originates in the back of the tongue Shape of a butterfly Normally not outwardly visible Biggest gland in the neck

CLASS OF HORMONE Produces hormones which regulate: Metabolic rate Heart and digestive function Muscle control Brain development Bone maintenance Thyroxine (T 4) Triiodothyionine (T3) Calcitonin Thyroxine (T4) Triiodothyionine (T3)

CELL SIGNALING PATHWAY Steroid hormone Thyroid hormone synthesized from tyrosine Water or lipid soluble Steroid and thyroid hormones are hydrophobic Can easily pass through the plasma membrane Bind to specific receptor proteins TSH then acts on the cells in the thyroid gland Initiate the synthesis and secretion of the thyroid hormone Stimulates a variety of metabolic processes that maintain body temperature

FEEDBACK(POSITIVE AND NEGATIVE) Positive feedback is much less common than negative feedback. Negative Feedback Hypothalamic-pituitary-thyroid axis Regulates TSH secretion Leads to hormone production House heating system

HYPOTHYROIDISM Too little thyroid hormone Common problem Associated with pregnancy Symptoms: Weight gain Sluggishness Fatigue Depression Cold intolerance Causes: Previous inflammation of the thyroid gland Autoimmune Thyroiditis Affects millions of Americans Some people do not know it affects them Pink: Normal Thyroid Blue: Hypothyroid

HYPERTHYROIDISM Too much thyroid hormone. Symptoms: Muscle weakness and/or fatigue Anxiety Trouble sleeping Mood swings Rapid heartbeat Causes: Graves’ disease (autoimmune disorder) Toxic nodular or multinodular goiters Pregnancy Treatment: Anti-thyroid medications Radioactive iodine Therapy Surgery Doctor may also prescribe beta blockers. Pink: Hyperthyroid Blue: Normal Thyroid

THYROIDITIS An inflammatory process ongoing within the thyroid gland. Findings of hypo- or hyper- thyroidism. Several types: Silent Thyroiditis Hashimoto’s Thyroiditis De Quervain’s Thyroiditis

THYROID CANCER Common malignancy Types: Anaplastic Thyroid Cancer Medullary Thyroid Cancer Follicular and/or Hurthle cell thyroid cancer Papillary and/or Mixed Papillary/Follicular Thyroid Cancer Treatment: Radioactive Iodine Thyroidectomy Most cases are very curable Vast majority has long term survival

GOITERS A mass will compress the trachea and esophagus Symptoms: Coughing Waking up from sleep, feeling like you can’t breathe Sensation that food is getting stuck in the upper throat Treatment: Thyroid hormone (pill form) Surgical removal

SOLITARY THYROID NODULES Lumps within a normal thyroid gland No symptoms Found by feeling a lump in the throat 95% of thyroid nodules are benign Health actions: contact a health physician after finding lump Majority can be cured Statistics: 1 in young women 1 in 40 young men At least 1 thyroid nodule: 50% of 50 year olds 60% of 60 year olds 70% of 70 year olds

SCIENTIFIC JOURNAL OVERACTIVE THYROID GLANDS PUT PATIENTS AT INCREASED RISK FOR DEVELOPING AF (ATRIAL FIBRILLATION) Data Joint 15 th International Congress of Endocrinology 14 th European Congress of Endocrinology Meeting Christian Selmer, MD Used 525,100 patients in a study of the relationship between thyroid dysfunction and the risk of atrial fibrillation. Cumulative Incidence Plots and Poisson Regression Models Measured TSH in the blood Subclinical Hypothyroidism --> lower risk for AF Subclinical Hyperthyroidism --> significant risk factor for AF

REFERENCES Endocrine Today. (2015). Overactive thyroid glands put patients at increased risk for developing AF. Retrieved from Sargis MD, PhD, R. M. (2015). Thyroid Gland Overview. Retrieved from Thyroid gland. (2015). Society for Endocrinology. Retrieved from WebMD. (2015). Understanding Thyroid Problems – the Basics. Retrieved from What Is the Role of Negative Feedback in the Endocrine System. (2015). Conjencture Corporation. Retrieved from Better Health Channel. (2015). State Government of Victoria. Retrieved from