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THYROID GLAND DISORDERS  GENERAL ASPECTS OF THYROID GLAND –Anatomy: weight range from 12 to 30g –Located in the neck, anterior to the traquea –Produces:

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Presentation on theme: "THYROID GLAND DISORDERS  GENERAL ASPECTS OF THYROID GLAND –Anatomy: weight range from 12 to 30g –Located in the neck, anterior to the traquea –Produces:"— Presentation transcript:

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2 THYROID GLAND DISORDERS

3  GENERAL ASPECTS OF THYROID GLAND –Anatomy: weight range from 12 to 30g –Located in the neck, anterior to the traquea –Produces: T4 & T3 (active hormone) –Regulation: “negative Feed-back” axis

4 THYROID GLAND DISORDERS –THYROID GLAND REGULATION “negative Feed-back” axis –Hypothalamus (TRH positive effect) –Pituitary gland (TSH, positive effect) –Thyroid gland T3 & T4 (negative effect)

5 THYROID GLAND DISORDERS  Thyroid hormones: –T4: (Thyroxine) is made exclusively in thyroid gland Ratio of T4 to T3 ; 5::1 Potency of T4 to T3; 1::10 T4 is the most important source of T3 by peripheral tissue deiodination “ T4 to T3 “

6 THYROID GLAND DISORDERS  Thyroid hormones: –T3: (Triiodothyronine) main source is peripheral deiodination: Ratio of T3 to T4 ; 1::5 Potency of T3 to T4; 10::1 T3 is the most important because more than 90% of the thyroid hormones physiological effects are due to the binding of T3 to Thyroid receptors in peripheral tissues.

7 THYROID GLAND DISORDERS  PHYSIOLOGY EFFECTS OF THYROID HORMONES  THEY ARE NOT ESSENTIAL FOR LIFE, BUT ARE EXTREMELY HELPFUL

8 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS: –Affects every single cell in the body Modulates: –Oxygen consumption –Growth rate –Maturation and cell differentiation –Turnover of Vitamins, Hormones, Proteins, Fat, CHO

9 THYROID GLAND DISORDERS  MECHANISMS OF THYROID HORMONE ACTION –Act by binding to Nuclear receptors, termed Thyroid Hormone Receptors (TRs), Increasing synthesis of proteins –At mitochondrial level increases number and activity to increasing ATP production –At Cell membrane increases ions and substrates transmembrane flux

10 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –CALORIGENESIS –GROWTH & MATURATION RATE –C.N.S. DEVELOPMENT & FUNCTION –CHO, FAT & PROTEIN METABOLISM –MUSCLE METABOLISM –ELECTROLYTE BALANCE –VITAMIN METABOLISM –CARDIOVASCULAR SYSTEM –HEMATOPOIETIC SYSTEM –GASTROINTESTINAL SYSTEM –ENDOCRINE SYSTEM –PREGNANCY

11 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –CALORIGENESIS Controls the Basal Metabolic Rate (BMR) –CHO METABOLISM Increases: –Glucose absorption of the GI tract –Glucose consumption by peripheral tissues –Glucose uptake by the cells –Glycolysis –Gluconeogenesis –Insulin secretion

12 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –GROWTH & MATURATION RATE –C.N.S. DEVELOPMENT & FUNTION “ESSENTIAL” in the newborn to prevent development of “CRETINISMS” & to a normal “IQ” Modulation of brain cerebration Mood modulation

13 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS - FAT & PROTEIN METABOLISM Increase lipolysis and lipid mobilization with: –Cholesterol –Triglicerides –Free fatty acids –MUSCLE METABOLISM Modulates; –Strength & velocity of contraction

14 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –ELECTROLYTE BALANCE Low Thyroid hormones could induce hyponatremia –VITAMIN METABOLISM Modulates vitamin consumption –HEMATOPOIETIC SYSTEM Could induce anemia

15 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –CARDIOVASCULAR SYSTEM Hyperthyroidism, increases: –Heart rate & myocardial strenght –Cardiac output –Peripheral resistances (Vasodilatation) –Oxygen consumption –Arterial pressure Hypothyroidism, reduces: –Heart rate & myocardial strenght –Cardiac output –Peripheral resistances (Vasodilatation) –Oxygen consumption –Arterial pressure

16 THYROID GLAND DISORDERS  THYROID HORMONE EFFECTS –GASTROINTESTINAL SYSTEM Modulate bowel movements and absorption –ENDOCRINE SYSTEM Modulates pituitary axis, affecting GH, ACTH, FSH, LH, so-on –PREGNANCY Modulates growth rate and affects lactation

17 THYROID GLAND DISORDERS  DIVIDED INTO: –THYROTOXICOSIS (Hyperthyroidism) Overproduction of thyroid hormones –HYPOTHYROIDISM (Gland destruction) Underproduction of thyroid hormones –NEOPLASTIC PROCESSES Beningn Malignant

18 THYROID GLAND DISORDERS  LABORATORY EVALUATION TSH normal, practically excludes abnormality –If TSH is abnormal, next step: Total & Free T4 & T3 -TSI (Thyroid Stimulating Ig) -TPO (Thyroid Peroxidase Ab) -Antimitochondrial Ab -Serum Tg (Thyroglobulin) -Radioiodine uptake & Thyroid scaning -FNA, Fine-needle aspiration -Thyroid ultrasound

19 THYROID GLAND DISORDERS  TSH High usually means Hypothyroidism –Rare causes: TSH-secreting pituitary tumor Thyroid hormone resistance Assay artifact  TSH low usually indicates Thyrotoxicosis –Other causes First trimester of pregnancy After treatment of hyperthyroidism Some medications (Esteroids-dopamine)

20 THYROID GLAND DISORDERS  THYROTOXICOSIS: –is defined as the state of thyroid hormone excesss  HYPERTHYROIDISM: –is the result of excessive thyroid gland function

21 THYROID GLAND DISORDERS  Abnormalities of Thyroid Hormones –Thyrotoxicosis Primary Secondary Without Hyperthyroidism Exogenous or factitious –Hypothyroidism Primary Secondary Peripheral

22 THYROID GLAND DISORDERS  Causes of Thyrotoxicosis : –Primary Hyperthyroidism Grave´s disease Toxic Multinodular Goiter Toxic adenoma Functioning thyroid carcinoma metastases Activating mutation of TSH receptor Struma ovary Drugs: Iodine excess

23 THYROID GLAND DISORDERS  Causes of Thyrotoxicosis: –Thyrotoxicosis without hyperthyroidism Subacute thyroiditis Silent thyroiditis Other causes of thyroid destruction: –Amiodarone, radiation, infarction of an adenoma Exogenous/Factitia –Secondary Hyperthyroidism TSH-secreting pituitary adenoma Thyroid hormone resistance syndrome Chorionic Gonadotropin-secreting tumor Gestational thyrotoxicosis

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25 THYROTOXICOSIS  Symptoms: –Hyperactivity –Irritability –Dysphoria –Heat intolerance & sweating –Palpitations –Fatigue & weakness –Weight loss with increased appetite –Diarrhea –Polyuria –Sexual dysfunction  Signs: –Tachycardia –Atrial fibrillation –Tremor –Goiter –Warm, moist skin –Muscle weakness, myopathy –Lid retraction or lag –Gynecomastia –* Exophtalmus –* Pretibial myxedema

26 THYROID GLAND DISORDERS  Differential diagnosis: –Panic attacks –Psychosis –Mania –Pheochromocytoma –Hypoglycemia –Occult malignancy

27 THYROID GLAND DISORDERS  Treatment: –Reducing thyroid hormone synthesis: Antithyroid drugs (Methimazole, Propylthyouracil) Radioiodine ( 131 I) Subtotal thyroidectomy –Reducing Thyroid hormone effects: Propranolol Glucocorticoids Benzodiazepines –Reducing peripheral conversion of T4 to T3 Propylthyouracil Glucocorticoids Iodide (Large oral or IV dosage) (Wolf-Chaikoff effect)

28 THYROID GLAND DISORDERS  Treatment: Special considerations: –Thyrotoxic crisis or Thyroid storm: It´s a life-threatening exacervation of thyrotoxicosis, acompanied by fever, delirium, seizures, coma, vomiting, diarrhea, jaundice. Mortality rate reachs 30% even with treatment It´s usually precipitated by acute illness, such as: –Stroke, infection,trauma, diabeic ketoacidosis, surgery, radioiodine treatment Propylthyouracil IV or Nasogastric tube Radioiodine ( 131 I) Propranolol Glucocorticoids Benzodiazepines Iodide (Large oral or IV dosage) (Wolf-Chaikoff effect)

29 THYROID GLAND DISORDERS  HYPOTHYROIDISM –Primary Autoimmune (Hashimoto´s) Iatrogenic Surgery or 131 I Drugs: amiodarone, lithium Congenital (1 in 3000 to 4000) Iodine defficiency Infiltrative disorders

30 THYROID GLAND DISORDERS  Hashimoto´s Thyroiditis or Goitrous thyroiditis  –Mean anual incidence: Women 4:1000 Men 1:1000 Risk factors; TPO antibodies (90%) Japanese, previous history, high I intake Average age: 60 Frequently associated to other autoimmune disorders such as: AR, SLE, Sjogren´s so-on. Treatment: Levothyroxine

31 THYROID GLAND DISORDERS  CONGENITAL HYPOTHYROIDISM  Prevalence: 1 in 3000 to 4000 newborns –Cause: Dysgenesis 85% –Dx: Blood screning (TSH &/or T4)  Treatment: –Supplemental Tx. With Levothyroxine is “essential” for a normal C.N.S. Development and prevention of mental retardation

32 THYROID GLAND DISORDERS  HYPOTHYROIDISM –Secondary Pituitary gland destruction Isolated TSH deficiency Bexarotene treatment Hypothalamic disorders –Peripheral: Rare, familial tendency

33 HYPOTHYROIDISM  Symptoms: –Tiredness –Weakness –Dry skin Sexual dysfunction –Dry skin –Hair loss –Difficulty concentrating  Signs: –Bradycardia –Dry coarse skin –Puffy face, hands and feet –Diffuse alopecia –Peripheral edema –Delayed tendon reflex relaxation –Carpal tunel syndrome –Serous cavity effusions.

34 THYROID GLAND DISORDERS  SPECIAL TREATMENT CONSIDERATIONS  Myxedema coma –Reduced level of consciousness, seizures –Hypotension/shock –Hypothermia –Hyponatremia  Usually in elderly hypothyroid pts.  Usually precipitated by intercurrent illnesses that impairs ventilation  It´s an Emergency with a high mortality rate  Treatment: Lyotironine(T3) or T4, Hydrocortisone, external warming, IV fluids

35 THYROID GLAND DISORDERS  SPECIAL TREATMENT CONSIDERATIONS  Elderly patients  Coronary Artery Disease  Poor adrenal gland reserve  Childrens  Pregnancy  Emergency surgery (Non thyroid related)

36 THYROID GLAND DISORDERS  THYROID GLAND NEOPLASIAS  Out of the focus of this lecture

37 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.37 Endocrine System  Hormones –Internal secretions  Produced by ductless glands  Secrete directly into bloodstream  Drugs –Natural or synthetic

38 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.38 Categories  Pituitary hormones  Adrenal corticosteroids  Thyroid agents  Antidiabetic agents

39 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.39 Pituitary  Located at the base of the brain  Master gland  Secretes four hormones

40 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.40 Somatotropin  Anterior pituitary lobe hormone  Human growth hormone (HGH)  Regulates growth  Treated by an endocrinologist

41 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.41 Adrenocorticotropic Hormone  ACTH  Parenteral use –Corticotropin  Used for diagnosis of adrenocortical insufficiency

42 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.42 Adrenal Corticosteroids  Adrenal glands adjacent to kidneys  Secrete corticosteroids  Act on the immune system  Uses –Replacement therapy –Anti-inflammatory –Immunosuppressent properties

43 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.43 Corticosteroid Therapy  Not curative  Supportive therapy  Conditions treated with corticosteroids  Effects of prolonged administration  Alternate-day therapy

44 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.44 Corticosteroid Therapy  Withdrawal of therapy  Side effects  Contraindications or extreme caution  Interactions  Patient education

45 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.45 Thyroid Agents  Natural or synthetic  Replacement therapy  Conditions requiring treatment  Diagnosis with blood tests  If patient euthyroid –Treatment contraindicated

46 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.46 Thyroid Agents  Treatment required for life  Periodic lab tests recommended  Toxic effects  Contraindications or extreme precautions  Interactions  Patient education

47 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.47 Antithyroid Agents  Relieve symptoms of hyperthyroidism  Used in preparation for surgical or radioactive iodine therapy  Side effects  Contraindication or caution  Interactions  Patient education

48 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.48 Antidiabetic Agents  Administered to lower blood glucose levels  Impaired metabolism of CHO, fats, and proteins  Diabetes mellitus –Insulin dependent (Type I, IDDM) –Non-insulin dependent (Type II, NIDDM)

49 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.49 Insulin  Used in Type I  Sometimes used in Type II  Must be administered parenterally  Other forms in clinical trials  Made from pork, beef-pork, biosynthetic human, or analogue

50 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.50 Insulin  U-100  Insulin syringes  Doses must be double-checked before administration  Differ in onset, peak, and duration of action

51 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.51 Insulin Types  Rapid  Short  Intermediate  Long  Mixtures

52 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.52 Insulin Administration

53 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.53 Regular Insulin  Rapid action and short duration  Can be administered IV or SC  Drawn up first when mixed with other insulins  Sliding scale varies with individual

54 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.54 Hyperglycemia  Causes  Symptoms  Treatment of acute hyperglycemia  Insulin interactions

55 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.55 Hypoglycemia  Causes  Symptoms  Treatment

56 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.56 Oral Antidiabetic Agents  Type II diabetes  How administered  Weight reduction and modified diets  Symptoms of Type II diabetes

57 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.57 Sulfonylureas  First-generation agents  Second-generation agents  Increase insulin production from the pancreas  Improve peripheral insulin activity

58 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.58 Sulfonylureas  Side effects  Contraindications or extreme caution  Interactions

59 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.59 Alpha-Glucosidase Inhibitors  Delay digestion of complex CHO and glucose absorption  Used with sulfonylurea medications  Side effects  Contraindications or extreme precautions  Drug interactions

60 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.60 Biguanides  Decrease hepatic glucose output and enhance insulin sensitivity in muscle  Can be used as monotherapy or with sulonylureas  Side effects  Contraindications or extreme precautions  Drug interactions

61 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.61 Meglitinides  Stimulate beta cells of pancreas to produce insulin  Used as monotherapy or with metformin  Side effects  Contraindication or extreme caution  Drug interactions

62 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.62 Thiazolidinediones  Decrease insulin resistance  Improve sensitivity to insulin in muscle and adipose tissue  Used as monotherapy or with sulonylurea, insulin, or metformin

63 Copyright © 2007 by Thomson Delmar Learning. ALL RIGHTS RESERVED.63 Thiazolidinediones  Side effects  Contraindications or extreme caution  Drug interactions  Patient education


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