Thyroid  Disorders
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Thyroid Disorders

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Thyroid  Disorders Thyroid Disorders Presentation Transcript

  • Thyroid Disorders Tapan A. Patel Cuong Nguyen Mona Jamaldinian
  • Thyroid Gland
    • Second largest endocrine gland in body
    • Small butterfly shaped gland located at base of neck below the sternocleidomastoid muscles
    • Thyroid is controlled
    • by the hypothalmus
    • and pituitary
  • Functions
    • Stimulates & maintains metabolic processes
      • Produces thyroid hormones T3-triiodothyronine and T4-thyroxine
      • These hormones regulate metabolism & affect the growth and function of other systems in the body
    • Secretes calcitonin to lower serum calcium levels
    • Parathyroid gland secretes PTH to raise serum calcium levels
  • Functions
    • Metabolic stimulants of:
      • Neural and skeletal development
      • Oxygen consumption at rest
      • Stimulating bone turnover by increasing formation and resorption
      • Promoting chronitropic and ionotropic effects
      • Increasing number of catecholamine receptors in heart
      • Increasing production of RBC
      • Altering the metabolism of carbs, fats, and protein
  • Hormones: T3 & T4
    • T3 (Triiodothyronine) & T4 (Tetraiodothyronine
      • Stored in Follicles (round sacs) in the thyroid filled with thyroglobulin, a thyroid protein.
        • Dietary iodine enters follicles where they are stored as T3 and T4
      • T4 is converted to T3 by peripheral organs such as kidney, liver, and spleen
      • T3 is 10x more active than T 4
  • Hormones: T4 to T3
      • Only 20% of total T3 is secreted by thyroid
        • Majority is formed from catalysis of T4 by 5’-iodthryonine deiodinase (highest activity in liver and kidney)
  • Hormones: T4
    • T4-thyroxine contains 4 iodine atoms
    • It is a slow-acting pre-hormone
    • T4 takes 4 days to peak in blood
      • Half-life 7 days
    • Overall effects take 6 weeks
    • T3 is the active and faster-acting hormone
    • The immediate effects of T3 last 1-2 days
      • Half-life 1.5 days
  • Iodine
    • Dietary Iodide is removed from the bloodstream by means of an active pump
    • The pump can concentrate iodide in the follicular sacs at 350x greater than the blood concentration
    • Oxidation of iodide by thyroid peroxidase converts iodide  iodine
    • Peripheral de-iodination of T4 to T3 is regulated by many factors including health, nutritional status, and other hormones
  • Hormones- TSH
    • TSH
      • TSH is a pituitary hormone
      • Controlled by TRH-thyrotropin releasing hormone from hypothalamus
      • Functions to stimulate thyroid hormone production
        • May enlarge thyroid (goiter) when under producing
      • Labs:
        • High TSH indicates low thyroid hormone= hypo
        • Low TSH indicates high thyroid hormone = hyper
  • Hormones-Calcitonin & PTH
    • Produced by thyroid to regulate serum calcium levels
    • Calcitonin stimulates movement of calcium into bone
    • Parathyroid hormone (PTH) opposite effect of calcitonin
  • Negative Feedback System The disruption of any of these mechanisms can cause abnormal levels of T3 and T4 leading to thyroid disease TRH T3 & T4 Thyroid TSH
  • Diseases
    • Hypothyroidism-Under Activity
    • Prevalence
      • Affects 5-17% of population
      • Females> Males
      • Higher in >60 years old
    • Types
      • Hashimoto’s thyroiditis
      • Ord’s thyroiditis
      • Postoperative hypothyroidism
      • Postpartum hypothyroidism
      • Iatrogenic hypothyroidism
  • Diseases
    • Hyperthyroidism- Over activity
    • Prevalence
      • Affect 5-17% of population
      • Females> Males
      • More common in younger persons
    • Types
      • Thyroid storm
      • Graves disease
      • Toxic thyroid nodule
      • Plummers disease
      • Hashitoxicosis
      • De Quervain thryoiditis
      • Iatrogenic hyperthyroidism
  • Labs 80-220ng/dL Bound & Free T 3 Total(T 3 ) 0.25-6.7U/mL Thyroid stimulating hormone TSH 22-34% Binding capacity of TBG T 3 Resin Uptake 80-220ng/dL Bound & Free T 3 Total T 3 (TT 3 ) 0.8-1.5 ng/dL Free T 4 Free T 4 (FT 4 ) 4.5-12.5mg/dL Bound & Free T 4 Total T 4 (TT 4 ) Normal Range Measurement Thyroid Function Test
  • Labs
    • Hyperthyroidism
      •  FT4
      •  TSH
    • Hypothyroidism
      •  FT4
      •  TSH
  • Hyperthyroidism-Types
    • Graves disease
      • Most common form (70-80%)
        • Autoimmune disorder in which thyroid-stimulating antibodies are circulating in blood. These bind to thyroid cells and activate cells in the same manner as TSH.
      • 7 times greater in women
      • Peak onset is 20-30’s
  • Hyperthyroidism-Types
    • Can be caused by:
      • Toxic multinodular goiter
      • Solitary toxic nodule
      • Thyroiditis
      • Drug-induced thryotoxicosis
      • Pituitary or trophoblastic tumors
  • Hyperthyroidism-Symptoms
    • Weight loss
    • Tachycardia
    • Bulging eyes
    • Nervous/Anxious
    • Insomnia
    • Intolerant of heat
    • Goiter
  • Goiter
    • A diet deficient in iodine
    • Increase in thyroid stimulating hormone (TSH) in response to a defect in normal hormone synthesis within the thyroid gland.
  • Thyroid Storm
    • Life threatening syndrome
    • Decompensated hyperthyroidism
    • Symptoms
      • Hyperthyroid symptoms with agitation, confusion, delirium, psychosis
      • Gastrointestinal: Nausea/Vomiting, Abdominal pain
      • Tachycardia associated with CHF
  • Thyroid Storm Treatment
    • Antithyroids
      • PTU 200-400mg po/NG q4-8h
      • Methimazole 60-120mg/d PO/NG divided q6-8h
    • Potassium Iodide 2-5 drops PO/NG q6h
    • Lugol Solution-Strong Iodine10 drops po TID
    • Glucorticoids: block conversion of T4 to T3
      • Hydrocortisone succinate 100-200mg IV q6-8
      • Dexamethasone 2mg Po/IV q6-8h
    • BB
      • Esmolol: 500mcg/kg/min
      • Propranolol 20-80mg/dose PO/NG q4-6h
  • Hyperthyroidism-Treatment
    • Drug Therapy
      • Beta blocker
        • Atenolol 50mg-100mg po daily
        • Propranolol 20-40mg po TID
      • Antithyroids
        • Methimazole 15-30mg po daily
        • Propylthiouracil (PTU) 300mg TID
  • Hyperthyroid-Treatment
    • Procedural Therapy
      • Radionuclide albation of thyroid gland
      • Total thyroidectomy
  • Methimazole
    • Methimazole prevents peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglubulin. Reduces T3 & T4 production.
    • Dosage
      • 15-30mg PO daily
  • Methimazole
    • Adverse Effects
      • Skin rash
      • Loss of taste
      • GI upset
      • Drowsiness
      • Decreased Platelets
    • antagonistic properties of Methimazole
  • Methimazole
    • Drug Interactions:
      • Discontinue before treatment with radioiodine; affects uptake
      • Amiodarone: Increases T3 and T4 serum levels
      • Warfarin: enhanced due to vitamin K
  • Propylthiouracil -PTU
    • Thio-urea derivative
    • Preferred agent in pregnant women
    • DOC for severe thyrotoxicosis
    • Dosage
      • Adults: 300-450mg/day divided q8h
      • Severe cases: 600-1200mg/day
      • Maintenance dose 100-150mg/day divided q 8-12 hours
    • Drug Interactions
      • Similar to Methimazole
  • PTU
    • Adverse reactions
      • Rash
      • Itching
      • Hives
      • Agranulocytosis
      • Vasculitis
  • Carbimazole-UK
    • Pro-drug converted to active form -methimazole
    • Dosage
      • 15-40mg PO daily until normal function
      • Reduce to 5-15mg po daily maintenance dose
    • Adverse Effects
      • Bone marrow suppression
      • Neutropenia
      • Agranulocytosis
  • Sodium Iodide I-131 (Iodotope)
    • Quickly absorbed and taken up by thyroid
    • No other tissue capable of retaining radioactive iodine therefore low adverse effects
    • Dose
      • Adult 75-150mCi/g of thyroid x estimated thyroid gland size
      • 24hour radioiodine uptake
      • Discontinue antithyroid therapy 3-4days before
  • Hypothyroidism
    • Types:
      • Primary hypothyroidism
        • Most common cause
        • Failure of thyroid gland
        • Occurs primarily in women aged 30-50 years old
          • Chronic autoimmune thyroiditis or Hashimotos disease is the most common primary hypothyroidism AND hypothyroidism overall
      • Secondary Hypothyroidism
      • Tertiary Hypothyroidism
      • Other causes
  • Hypothyroidism-Symptoms
    • Fatigue
    • Weight Gain
    • Depression
    • Dry skin
    • Bradycardia
    • Constipation
    • Intolerant to cold
  • Hashimoto’s Disease
    • Autoimmune disorder in which antibodies are directed against a thyroid sites to :
      • Inhibit thyroid peroxidase
      • Inhibit effects of TSH
      • Stimulate thyroid growth
  • Hypothyroidism-Primary
    • Drug induced
      • Amiodarone, lithium, thiocyanates, phenylbutazone, sulfonylureas, PTU & methimazole
    • Iatrogenic
      • Surgical removal of the thyroid gland and radiation treatment
  • Primary Hypothyroidism
    • Thyroid gland failure
      • Decrease T3 & T4
      • Increase TRH due to negative feedback
      • Increased TSH due to decreased TRH
  • Secondary Hypothyroid
    • Pituitary failure
      • Insufficient TSH release as a result of:
        • Pituitary tumors
        • Surgery
        • Pituitary radiation
        • Pituitary necrosis
        • Autoimmune mechanisms
  • Tertiary Hypothyroidism
    • Hypothalamic Failure- very rare
    • Insufficient TRH release as a result of:
      • Trauma
      • Irradiation
      • Tumors
  • Hypothyroidism-Treatment
    • Drug Therapy
      • Levothyroxine Sodium-DOC synthetic T4
        • Adults 1-1.5mgc/kg/day orally initially, adjust as needed. Average dose 1.6-1.8mcg/kg/day
        • Pediatrics 1-1.5mgc/kg/day. Average 4 mcg/kg/day
      • Thyroid (Armour)
        • 30mg PO daily, increase 15mg q 2-3 week
      • Liotrix (Thyrolar) synthetic combo T3 & T4
        • Thyrolar 1/2 (6.25/25mcg) start1 tab daily , increase PRN q 2-3 weeks.
      • L-triiodothyronine (Cytomel) synthetic T3
        • 25mcg PO daily/ increase 12.5-25mcg daily every 1-2 weeks
  • Hypothyroidism-Treatment
    • Adverse Effects
      • MI
      • Osteopenia
      • HA
    • Contraindicated
      • Acute MI
      • Treatment of obesity
      • Uncontrolled HTN
  • Monitoring
    • Obtain baseline FT4, TSH, LFT, CBCs before initiation of therapy
    • Repeat FT4 and TSH after 4-6 weeks on therapy and 4-6 weeks after adjustments
    • Once euthyroid state obtain thyroid function test after 3-6 months
  •