Hyperthyroidism

Overview of Hyperthyroidism

Hyperthyroidism is an elevation of thyroid hormone (T3 and T4).

Classification

Most likely diagnosis

First line treatment

• Signs and symptoms
  • Nervousness (mania)
  • Emotional lability (mania)
  • Tremor
  • Insomnia
  • Sweating
  • Heat intolerance
  • Weight loss despite increased appetite
  • Diarrhoea
  • Palpitations (atrial fibrillation)
  • Warm/moist skin
  • Menstrual changes i.e. polymenorrhoea
  • Hypercalcemia
• Differentials
  • Primary hyperthyroidism: low TSH, high T3 and T4
  • Secondary hyperthyroidism: high TSH, high T3 and T4
  • Pheochromocytoma
  • Acute manic episode
  • Intoxication: cocaine, amphetamine
• Investigation
  • Thyroid Function Test
  • Urine toxicology screen

Graves Disease

Graves disease is an autoimmune thyroid disease caused by thyrotroping-stimulating immunoglobulins (TSIs) which stimulate TSH receptors resulting in elevated basal thyroid activity. Unlike toxic adenoma, 50% of patients with Grave’s disease undergo remission within the first year of treatment. This is why medical treatment, instead of surgery, is preferred for Grave’s disease.

Most common cause of hyperthyroidism. More common in women. Age of onset is on average 20 – 40 years. Associated with other autoimmune disorders (HLA-B8)

• Signs and symptoms
  • Hyperthyroid symptoms
  • Exophthalmos (deposition of glycosaminoglycans in
  • Pretibial myxedema
• Physical exam
  • Tachycardia
  • Goiter
  • Warm/moist skin
  • Fine tremor
• Investigations
  • Thyroid function test: low TSH, high T3 and T4. High T3/T4 ratio suggests Graves disease over thyroiditis.
  • Serology for Thyroid-stimulating immunoglobulin (TSI): most accurate test
  • Complete blood count: normocytic anaemia
  • Calcium: hypercalcemia (T3 activates osteoclasts
  • RAIU scan: diffuse increased uptake
• Medical treatment
  • Propranolol to control symptoms
  • Propylthiouracil (choose in pregnant women in the first trimester) or Methimazole – antithyroid drugs
  • Radioiodine ablation is the definitive treatment
  • Steroids and/or Teprotumumab (Tepezza) for Graves ophthalmology and myxedema (may not respond to antithyroid medication)
• Surgical treatment (Indicated if the patient fails to respond to medical treatment)
  • Bilateral subtotal thyroidectomy
  • Radioactie Iodine ablation
• Contraindications for radioactive iodine ablation
  • Pregnant or nursing mothers
  • Patients with moderate-to-severe ophthalmopathy
  • Patients who smoke (worsens ophthalmopathy)
  • Patients with large goiters
  • Patients with severe thyrotoxicosis requiring rapid control
• Complications of thyroidectomy
  • Thyroid storm
  • Hemorrhage
  • Hypoparathyroidism
  • Recurrent Laryngeal Nerve Injury

Toxic Nodular Goiter

Toxic nodular goiter can be caused by a single nodule (toxic adenoma) or multiple nodules (**toxic multinodular goiter AKA Plummer’s disease)**They are the second most common cause of hyperthyroidism. Plummer’s disease is progressive and requires ablation or surgery to definitively treat the disease. Radioactive iodine ablation is less likely to be successful for Plummer’s disease than a toxic adenoma due to the large amounts of thyroid tissue needed to be ablated. Surgery is recommended for patients with large nodules and/or compressive symptoms.

They have an increased incidence in post-menopausal women.

• Signs and symptoms
  • Hypermetabolic state (more subtle than grave’s disease)
  • Weight loss
  • Occasionally asymptomatic
• Physical exam
  • Tachycardia
  • Nodules(s) may or may not be palpable
• Investigations
  • TSH level, T3/T4: Best initial diagnostic test
    • Low TSH
    • Elevated T3/T2
  • Radioactive iodine uptake scan (RAIU)
    • Increased uptake in nodules
• Medical treatment
  • Propranolol and Antithyroid drugs (PTU, Methimazole)
  • Radioactive Iodine Therapy (definitive treatment)
• Surgical treatment (definitive treatment)
  • Total thyroidectomy for Plummer’s disease
  • Thyroid lobectomy for toxic adenoma

Thyroiditis

Thyroiditis is inflammation of the thyroid gland.

Acute (Suppurative) Thyroiditis

Acute thyroiditis is a rare bacterial infection (abscess) of thyroid tissue seen in immunocompromised patients. It can be caused by a persistent pyriform sinus fistula or trauma. Most common causes are Staphyloccocus aureus and Streptococcus.

• Risk factors
  • immunosuppression
• Signs and symptoms
  • Pain and tenderness: anterior neck pain radiating to the jaw and ears
  • Erythema over the thyroid gland
  • Fever
• investigations
  • TFTs: normal
  • CBC: Leukocytosis
  • CT-scan neck: best diagnostic step
  • Needle aspiration and culture of the suppuration
  • HIV test
• Treatment
  • Incision and Drainage of the abscess
  • Broad-spectrum antibiotics (piperacillin/tazobactam + vancomycin)

Subacute (de Quervain) Thyroiditis

Subacute thyroiditis is inflammation of the thyroid gland occurring as a post-viral inflammatory response. It is associated with viral infections (coxsackievirus, mumps, measles, adenovirus, infectious mononucleosis). It is the most common cause of a painful thyroid gland. Another painless subtype exists as an autoimmune-driven phenomenon in post-partum women.

• Signs and symptoms
  • Enlarged, painful thyroid gland that is firm
  • Hyperthyroid symptoms
• Stages of subacute thyroditis
  • Hyperthyroidism → euthyroidism → transient hypothyroidism → resolution of symptoms
• Treatment
  • Pain management (NSAIDs)
  • Treatment of hyper- and hypothyroidism
  • Steroids (if there is severe swelling)

Reidel’s Thyroidisits

Reidel’s thyroiditis is an idiopathic, rare condition where the thyroid becomes densely fibrotic. Commonly associated with hypothyrodism. Possibly autoimmune in etiology. Patient usually present with compressive symptoms and hypothyroidism.

• Patient history
  • Middle-aged woman presenting with a rock hard thyroid on exam
• Signs and symptoms
  • Hypothyroidism
  • Symptoms related to compression: dyspnoea, dysphagia, tightness, neck pressure, hoarseness, cough
• Physical exam
  • Firm, non-tender thyroid
• Investigations
  • Biopsy: to exclude carcinoma
• Medical treatment
  • Prednisone
  • Levothyroxine for hypothyroidism
• Surgical treatment
  • Considered for compressive symptoms

Hashimoto’s Thyroiditis (Chronic Lymphocytic Thyroiditis)

Hashimoto’s thyroiditis is an autoimmune inflammation of the thyroid gland caused

• Associations
  • Increased risk of thyroid lymphoma and thyroid cancer
• Physical examination
  • Small firm thyroid → enlarged goiter
  • Hypothyroidism
• Investigations
  • Anti-TPO antibodies: present (90-100%). As well as other antibodies for the thyroid.
• Treatment
  • Treat hypothyroidism
  • Surgery for goiter with compressive symptoms