Review of Thyroid Dysfunction
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The document summarizes the target tissue effects, mechanisms of action, and treatment approaches for hyperthyroidism and hypothyroidism. It discusses the causes, signs and symptoms, diagnostic testing, and medication options for managing different types of thyroid disorders. Key points covered include the effects of thyroid hormones on various organ systems, methods for evaluating thyroid function, distinguishing autoimmune from other etiologies, and protocols for replacing thyroid hormone in deficiency or reducing excess levels.
Review of Thyroid Dysfunction
- 1. Kristopher Maday, MS, PA-C Program Director/Associate Professor University of Tennessee Health Science Center Physician Assistant Program
- 3. Target Tissue Effect Mechanism Heart Chronotropic Increase number and affinity of β- adrenergic receptors Inotropic Enhance responses to circulating catacholamines Adipose Tissue Catabolic Stimulate lipolysis Muscle Catabolic Increase protein breakdown Bone Developmental Metabolic Promote normal skeletal development, accelerates bone turnover Nervous System Developmental Promote normal brain development Gut Metabolic Increase rate of carbohydrate absorption Lipoprotein Metabolic Stimulates LDL receptor formation Metabolism Calorigenic Increases metabolic rate by stimulating O2 consumption of metabolically active tissues
- 4. • Infectious – Staphylococcus, streptococcus – Signs and Symptoms • Rapid onset • Neck pain, fever, chills, dysphagia – Ultrasound to evaluate for abscess – Treatment • IV antibiotics PO after 2-3d defervescence
- 5. • Subacute – 2 main causes • Post-viral infection (2-8 weeks) • Autoimmune – Signs and Symptoms • Enlarged, tender thyroid – Laboratory • Elevated ESR or CRP • (+) thyroglobulin or thyroperoxidase • Variable thyroid panel
- 7. • Treatment
- 8. T3, T4
- 9. • Grave’s Disease – Most common cause of hyperthyroidism is US – Autoimmune disease • High association with other autoimmune diseases – Female:Male 8:1 – Onset in 20s-40s
- 11. • Toxic adenoma – Single – Plummer’s Disease – Multiple – Non-tender enlargement of thyroid
- 19. Thianamides Methimazole Propylthiouracil Onset Faster Slower Compliance Better Worse Cost Cheaper More expensive Initial Dosing 5-20mg TID 100-300mg TID Maintenance Dosing 5-15mg daily 30-50mg TID Pregnancy No Yes
- 23. Thyroid Storm
- 26. T3, T4
- 27. • Hashimoto’s Thyroiditis – Most common cause of hypothyroid in iodine sufficient countries – Thyroperoxidase and thyroglobulin antibodies
- 33. Initial Dosing 1.6 mcg/kg/day Levothyroxine Recheck TSH in 6 weeks Increase by 12.5-25 mcg/da
- 34. Temp – 93o F (33.8o C) HR – 50 bpm RR – 10 bpm Sodium – 130 mg/dL TSH – 258 mu/L T4 – 0.01 ng/dL
- 35. Thyroid Hormones Levothyroxine Triiodothyronine Load – 200-400 mcg Load - 5-20 mcg Maintenance – 1.6 mcg/kg/day Maintenance – 2.5-10 mcg TID Fluid resuscitation Stress dose steroids Rewarming
- 37. w w w . p a i n e p o d c a s t . c o m
Editor's Notes
- #3: T3 > T4 Triiodothyronine 90% is derived from peripheral deiodination of T4 Thyroxine
- #6: Hashimoto’s autoimmune De Quarvain’s post-viral
- #8: Supportive Pain control Thyroid dysfunction
- #12: Notice the right lobeatrophy in response to the hyeprfucntioning left lobe
- #14: Amiodorone induced
- #17: Trial fibrillation and premature atrial complexes Tracheal compression
- #19: Propanolol in high doses (>160mg/day) can block peripheral diodination of T3
- #20: Propanolol in high doses (>160mg/day) can block peripheral diodination of T3
- #21: Panel A shows the processing of radioiodine in a thyroid follicle. The thyrotropin receptor and the sodium–iodine symporter (NIS) are located on the basolateral membrane. Iodine is actively transported across the apical membrane in a pendrin-dependent process. In the presence of hydrogen peroxide, thyroid peroxidase facilitates the iodination of the tyrosyl residues of thyroxin. The resulting compound is subsequently coupled to form free thyroxine (T4) and triiodothyronine (T3). Panel B shows the patterns of radioiodine uptake into the thyroid in Graves' disease (diffuse uptake), in toxic adenoma (focal uptake), and in toxic nodular goiter (focal or patchy uptake), which has both autonomous and nonfunctioning nodules.
- #29: Amiodorone, lithium
- #34: May start lower in older patients Symptoms improve in 2 weeks Titrate for symptoms and normalization of TSH
- #35: Severe, life-threatening hypothyroidism Same symptoms as hypothyroidism, but much more severe AMS, coma, seizures, hypothermia, hyponatremia, “doughy” skin Causes Systemic illness or sudden cessation of levothyroxine
- #36: T3 is continued until symptoms abate patient becomes stable