Thyroid Diseases

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Thyroid Diseases

• An Update
• Chris Place, MD

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Aspects That Will Be Addressed

• Hyperthyroidism
• Hypothyroidism
• Thyroiditis
• Iodine-induced thyroid disease

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Thyroid Functions

• Cardiovascular? B adrenergic receptors
• GI? peristalsis and vitamin A
• CNSmentation and development
• MSprotein metabolism, growth and maturation
• Respiratory? surfactant synthesis
• CHO metabolism

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Hyperthyroidism
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Hyperthyroidism Symptoms

• Hyperactivity/ irritability/ dysphoria/ insomnia
• Heat intolerance and sweating
• Palpitations
• Fatigue and weakness
• Weight loss with increase of appetite
• Diarrhea
• Polyuria
• Oligomenorrhoea, loss of libido

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Hyperthyroidism Signs

• Tachycardia (AF)
• Tremor
• Goiter
• Warm moist skin
• Proximal muscle weakness
• Lid retraction or lag
• Gynecomastia
• Hair/nail changes

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Causes of Hyperthyroidism

• Most common causes
• Graves disease
• Toxic multinodular goiter
• Autonomously functioning nodule

• Rarer causes
• Thyroiditis or other causes of destruction
• Thyrotoxicosis factitia
• Iodine excess (Jod-Basedow phenomenon)
• Struma ovarii
• Secondary causes (TSH or ßHCG)

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Graves Disease

• Autoimmune disorder
• Abs directed against TSH receptor with intrinsic
  activity. Thyroid and fibroblasts
• Responsible for 60-80 of Thyrotoxicosis
• More common in women

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Graves Disease

• Autoimmune with over activity of thyroid gland
• HLA-DR3 association
• Defect in suppressor T cells
• B cells synthesize thyroid-stimulating
  immunoglobulin (TSI)
• Autoantibody against TSH receptor
• Gland becomes over stimulated and loses negative
  feedback to T3 and T4

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Graves continued

• Associations
• Viral/bacterial infections
• Stress
• Exposure to iodide

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Graves Disease Eye Signs

• N - no signs or symptoms
• O only signs (lid retraction or lag) no
  symptoms
• S soft tissue involvement (peri-orbital oedema)
• P proptosis (gt22 mm)(Hertls test)
• E extra ocular muscle involvement (diplopia)
• C corneal involvement (keratitis)
• S sight loss (compression of the optic nerve)

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GravesOphthalmopathy
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Graves Disease Other Manifestations

• Pretibial mixoedema
• Thyroid acropachy
• Onycholysis
• Thyroid enlargement with a bruit frequently
  audible over the thyroid

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GravesDermopathy

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  e/3C8F3995-E45A-406A-B785837268AEED7B.htm?category
  questions

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Diagnosis of Graves Disease

• TSH ?, free T4 ?
• Thyroid auto antibodies
• Nuclear thyroid scintigraphy (I123, Te99)

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Treatment of Graves Disease

• Reduce thyroid hormone production or reduce the
  amount of thyroid tissue
• Antithyroid drugs propyl-thiouracil (PTU),
  carbimazole
• Radioiodine
• Subtotal thyroidectomy relapse after
  antithyroid therapy, pregnancy, young people?
• Symptomatic treatment
• Propranolol

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Considerations with Thionamides

• Both PTU and Methimazole may be used in pregnancy
• PTU and Methimazole are considered safe in
  breastfeeding
• Methimazole appears in higher concentrations
• Watch for agranulocytosis
• Fever
• Sore throat

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Thionamides Cont

• Measure FT4 and FTI every 2-4 weeks and titrate
  accordingly
• Goal is high normal range
• 90 see improvement in 2-4 weeks

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Iodine 131

• Contraindicated in pregnancy
• Avoid pregnancy for 4 months after 131I treatment
• Avoid breastfeeding for 120 days after 131I
  treatment
• Gestational age key when counseling pregnant
  women exposed to 131I

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Thyroid Storm

• Medical Emergency
• Occurs in 1 of pregnant pts with
  hyperthyroidism
• Diagnostic signs and symptoms
• Fever
• Tachycardia
• Altered mental status
• Vomiting and diarrhea
• Cardiac arrhythmia

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More on Thyroid Storm

• If suspected, draw lab
• FT4
• FT3
• TSH
• Start treatment immediately

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Toxic Adenomas

• Single Nodules
• Release excessive thyroid hormone
• Identified with radioactive scan
• Hot Nodule

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Toxic Nodular Goiter

• Develops from multinodular goiter
• Nodules become autonomous
• AKA Plummers disease

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Factitious Hyperthyroidism

• Excessive intake/exposure to thyroid hormone

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Hypothyroidism
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Hypothyroidism Symptoms

• Tiredness and weakness
• Dry skin
• Feeling cold
• Hair loss
• Difficulty in concentrating and poor memory
• Constipation

• Weight gain with poor appetite
• Hoarse voice
• Menorrhagia, later oligo and amenorrhoea
• Paresthesias
• Impaired hearing

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Hypothyroidism Signs

• Dry skin, cool extremities
• Puffy face, hands and feet
• Delayed tendon reflex relaxation
• Carpal tunnel syndrome
• Bradycardia
• Diffuse alopecia
• Serous cavity effusions

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Causes of Hypothyroidism

• Autoimmune hypothyroidism (Hashimotos, atrophic
  thyroiditis)
• Iatrogenic (I123treatment, thyroidectomy,
  external irradiation of the neck)

• Drugs iodine excess, lithium, antithyroid drugs,
  etc
• Iodine deficiency
• Infiltrative disorders of the thyroid
  amyloidosis, sarcoidosis,haemochromatosis,
  scleroderma

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Chronic Thyroiditis

• Hashimotos
• Autoimmune
• Initially goiter later very little thyroid tissue
• Rarely associated with pain
• Insidious onset and progression
• Most common cause of hypothyroidism
• TPO abs present (90 95)

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Hashimotos Thyroiditis

• MCC of hypothyroidism
• Autoimmune thyroiditis
• Women 30-50 years of age
• HLA-DR5

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Antibodies in Hashimotos

• Antimicrosomal abys
• Against peroxidase
• Antithyroglobulin abys
• Against thyroglobulin
• Autoantibodies against TSH receptor
• Net effect is prevent TSH stimulation of gland

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Associations with Hashimotos

• Sjogrens
• SLE
• Pernicious anemia

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Risks with Immune Mediated Thyroid Dysfunction

• Antibodies cross placenta
• In Graves
• TBII
• TSI
• In Graves1-5 of neonates have hyperthyroidism
  or neonatal Graves caused by maternal TSI
• Incidence low due to balance of antibodies with
  thioamide treatment

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Lab Investigations of Hypothyroidism

• TSH ?, free T4 ?
• Ultrasound of thyroid little value
• Thyroid scintigraphy little value
• Anti thyroid antibodies anti-TPO
• S-CK ?, s-Chol ?, s-Trigliseride ?
• Normochromic or macrocytic anemia
• ECG Bradycardia with small QRS complexes

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Treatment of Hypothyroidism

• Levothyroxine
• If no residual thyroid function 1.5 µg/kg/day
• Patients under age 60, without cardiac disease
  can be started on 50 100 µg/day. Dose adjusted
  according to TSH levels
• In elderly especially those with CAD the starting
  dose should be much less (12.5 25 µg/day)

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TFTs in Pregnancy and Disease
Maternal TSH FT4 FTI TT4 TT3 RT3U
Pregnancy No change No change No change ? ? ?
Hyperthyroid ? ? ? ? ? or no change ?
Hypothyroid ? ? ? ? ?or no change ?
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Thyroiditis
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Thyroiditis

• The most common form of thyroiditis is Hashimoto
  thyroiditis, this is also the most common cause
  of long term hypothyroidism
• The outcome of all other types of thyroiditis is
  good with eventual return to normal thyroid
  function

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Thyroiditis

• Acute rare and due to suppurative infection of
  the thyroid
• Sub acute also termed de Quervains thyroiditis/
  granulomatous thyroiditis mostly viral origin
• Chronic thyroiditis mostly autoimmune
  (Hashimotos)

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Acute Thyroiditis

• Bacterial Staph, Strep
• Fungal Aspergillus, Candida, Histoplasma,
  Pneumocystis
• Radiation thyroiditis
• Amiodarone (acute/ sub acute)
• Painful thyroid, ESR usually elevated, thyroid
  function normal

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Sub Acute Thyroiditis

• Viral (granulomatous) Mumps, coxsackie,
  influenza, adeno and echoviruses
• Mostly affects middle aged women, Three phases,
  painful enlarged thyroid, usually complete
  resolution
• Rx NSAIDS and glucocorticoids if necessary

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Sub Acute Thyroiditis (cont)

• Silent thyroiditis
• No tenderness of thyroid
• Occur mostly 3 6 months after pregnancy
• 3 phases hyper?hypo?resolution, last 12 to 20
  weeks
• ESR normal, TPO Abs present
• Usually no treatment necessary

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Clinical Course of Sub Acute Thyroiditis
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Chronic Thyroiditis

• Reidels
• Rare
• Middle aged women
• Insidious painless
• Symptoms due to compression
• Dense fibrosis develop
• Usually no thyroid function impairment

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Postpartum Thyroiditis

• May occur in 5 of women with no known thyroid
  disease
• Clinically
• 44 hypothyroid
• 33 thyrotoxicosis
• 33 thyrotoxicosis followed by hypothyroidism

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Postpartum Thyroiditis Cont

• Dx by abnormal TSH or FT4
• Screen symptomatic women only
• Aby screening may be useful

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Iodine-induced thyroid disease
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Iodine Deficient Hypothyroidism

• Risk of congenital cretinism
• Treatment with iodine in 1st and 2nd trimesters
  significantly reduces abnormalities of cretinism

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Cretinism
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Summary

• Thyroid affects multiple organ systems
• Pathology may be infectious, autoimmune, cancer,
  or combination
• Understand hormone levels change during pregnancy
• Adequate treatment is the key to preventing
  complications
• Recognize the many complications that may occur
  in pregnancy and respond accordingly