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Endocrine & Metabolic System

Hyperthyroidism

A condition resulting from excessive production and secretion of thyroid hormones (thyroxine - T4, triiodothyronine - T3) by the thyroid gland, leading to a hypermetabolic state.

Also known as: Overactive Thyroid, Thyrotoxicosis

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Referral and warning signs

When to refer

Refer ALL patients with confirmed hyperthyroidism to specialist (Endocrinologist/Physician) for: Determining underlying cause. Initiating and monitoring appropriate treatment (ATDs, RAI, surgery decisions). Management of Graves' ophthalmopathy. Management of thyroid storm (URGENT).

Red flags

  • Signs of Thyroid Storm (high fever, severe tachycardia, altered mental status, HF, GI upset)
  • Severe Graves' ophthalmopathy (visual loss, corneal exposure)
  • Atrial fibrillation with rapid ventricular response
  • Signs of heart failure
  • Significant unexplained weight loss
  • Agranulocytosis symptoms on ATDs (fever, sore throat)

Signs and symptoms

  • Weight loss despite increased appetite (hyperphagia)
  • Heat intolerance, excessive sweating
  • Palpitations, tachycardia (often sinus tach or atrial fibrillation)
  • Tremor (fine tremor of outstretched hands)
  • Anxiety, irritability, nervousness, emotional lability, insomnia
  • Fatigue, muscle weakness (especially proximal)
  • Diarrhoea / Frequent bowel movements
  • Goitre (often diffuse, smooth in Graves'; nodular in toxic MNG/adenoma)
  • Shortness of breath
  • Menstrual irregularities (oligomenorrhoea/amenorrhoea)
  • Specific signs of Graves' Disease:
  • - Ophthalmopathy/Exophthalmos (protruding eyes, lid lag, lid retraction, diplopia, periorbital oedema)
  • - Dermopathy (pretibial myxedema - thickened skin over shins, rare)
  • - Thyroid acropachy (clubbing with swelling of digits, rare)

Risk factors

  • Graves' disease (autoimmune - most common cause)
  • Toxic multinodular goitre (TMNG)
  • Toxic adenoma ('hot' nodule)
  • Thyroiditis (subacute, postpartum, Hashimoto's - transient hyperthyroid phase)
  • Excessive iodine intake (Jod-Basedow phenomenon)
  • Amiodarone use
  • Excessive intake of thyroid hormone medication (iatrogenic/factitious)

Diagnosis

Clinical assessment

Suspect based on symptoms of hypermetabolism (weight loss, heat intolerance, palpitations, tremor, anxiety) +/- goitre +/- eye signs (Graves'). Differentiate from anxiety disorders, pheochromocytoma, weight loss from other causes (malignancy, malabsorption, TB).

Investigations

  • Thyroid Function Tests (TFTs): Low/Suppressed TSH is the key finding. Elevated Free T4 (FT4) and/or Free T3 (FT3) confirms hyperthyroidism.
  • Thyroid Autoantibodies:
  • - TSH Receptor Antibodies (TRAb): Positive in most Graves' disease.
  • - Anti-TPO / Anti-Tg antibodies: May be elevated in Graves' or Hashimoto's thyroiditis.
  • Radioactive Iodine Uptake (RAIU) Scan: Differentiates causes. High uptake indicates increased hormone synthesis (Graves', toxic MNG/adenoma). Low uptake indicates hormone release from thyroiditis or exogenous intake.
  • Thyroid Ultrasound with Doppler: Assess gland size/structure, nodularity, vascularity ('thyroid inferno' in Graves').
  • ECG: Sinus tachycardia, atrial fibrillation common.

Diagnostic criteria

Suppressed TSH with elevated FT4 and/or FT3.

Management

Non-pharmacological management

  • Symptomatic relief (e.g., staying cool).
  • Radioactive Iodine (RAI) Therapy: Destroys thyroid tissue. Definitive treatment for Graves'/toxic nodules. Causes permanent hypothyroidism requiring lifelong levothyroxine. Contraindicated in pregnancy/breastfeeding.
  • Surgery (Thyroidectomy): Definitive treatment. Indicated for large goitres with compressive symptoms, suspected malignancy, patient preference, or intolerance/contraindication to other therapies. Causes permanent hypothyroidism.

Pharmacological treatment

  • Beta-blockers: Control adrenergic symptoms (palpitations, tremor, anxiety). Propranolol 10-40mg TID/QID (non-selective, also partially blocks T4->T3 conversion). Atenolol/Metoprolol (beta-1 selective) also used. Use until euthyroid achieved with other therapies.
  • Antithyroid Drugs (ATDs) - Thionamides: Inhibit thyroid hormone synthesis.
  • - Carbimazole: Starting dose 15-40mg daily (max 60mg), often divided initially. Maintenance dose 5-15mg daily. (Metabolized to Methimazole).
  • - Methimazole (MMI): Alternative, longer half-life, often preferred (except 1st trimester pregnancy).
  • - Propylthiouracil (PTU): Preferred in 1st trimester of pregnancy and thyroid storm (also blocks T4->T3 conversion). Higher risk of liver toxicity.
  • - Treatment duration typically 12-18 months for Graves', then attempt withdrawal (relapse common). Lifelong therapy may be needed if RAI/surgery not done/contraindicated.
  • - Monitor for side effects: Rash, arthralgia, GI upset, hepatitis, AGRANULOCYTOSIS (rare but serious - monitor WBC if fever/sore throat).

Monitoring

Monitor TFTs (TSH, FT4, FT3) regularly (e.g., every 4-6 weeks initially) to adjust ATD dose. Monitor TSH long-term after RAI/surgery (for hypothyroidism). Monitor CBC if agranulocytosis suspected on ATDs. Monitor symptoms.

Complications

  • Atrial fibrillation, heart failure (high-output)
  • Thyroid storm / Thyrotoxic crisis (life-threatening exacerbation - fever, tachycardia, delirium, HF)
  • Graves' ophthalmopathy (can progress independently)
  • Osteoporosis
  • Muscle weakness / Thyrotoxic myopathy
  • Emotional lability / Psychiatric symptoms
  • Complications of treatment (hypothyroidism after RAI/surgery, ATD side effects)

Prevention

  • Not generally preventable, but manage risk factors where applicable (e.g., smoking cessation may reduce Graves' ophthalmopathy risk).

Patient education

  • Explain hyperthyroidism and the specific cause.
  • Treatment options (ATDs, RAI, surgery) with pros/cons.
  • Importance of medication adherence (ATDs, beta-blockers).
  • Need for regular monitoring (TFTs, side effects).
  • ATD side effects: report fever/sore throat immediately (agranulocytosis risk).
  • Symptoms of thyroid storm requiring urgent care.
  • Eye care if Graves' ophthalmopathy present.
  • Radioactive precautions after RAI therapy.
  • Lifelong thyroid hormone replacement if RAI/surgery performed.

Uganda-specific notes

Graves' disease and toxic multinodular goitre are common causes. Access to TFTs, autoantibodies, RAIU scans, RAI therapy, and thyroid surgery limited. Carbimazole and Propranolol are the mainstay medical treatments available per UCG.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 8, Section 8.1.6

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