Doctors Revision

Endocrine & Metabolic System

Hypothyroidism

A condition resulting from insufficient production of thyroid hormones by the thyroid gland, leading to a generalized slowing of metabolic processes.

Also known as: Underactive Thyroid, Myxoedema (severe form)

Open in the interactive guide
On this page

Referral and warning signs

When to refer

Referral to specialist (Endocrinologist/Physician) for: Difficulty managing TSH levels. Suspected secondary/tertiary hypothyroidism (low TSH with low FT4). Severe symptoms or Myxoedema Coma (URGENT). Hypothyroidism in pregnancy or children. Significant co-morbidities (e.g., heart disease requiring cautious initiation).

Red flags

  • Signs of Myxoedema Coma (hypothermia, severe bradycardia, altered consciousness)
  • Associated cardiac symptoms (angina, heart failure)
  • Rapidly enlarging goitre
  • Symptoms suggestive of pituitary disease (headache, visual changes)

Signs and symptoms

  • Fatigue, lethargy, lack of energy
  • Weight gain (often modest)
  • Cold intolerance
  • Constipation
  • Dry skin, coarse hair, hair loss (including outer third of eyebrows)
  • Puffy face (myxoedema), periorbital oedema
  • Hoarse voice, slow speech
  • Bradycardia (slow heart rate)
  • Muscle aches (myalgia), stiffness, cramps
  • Menstrual irregularities (heavy periods - menorrhagia)
  • Depression, slowed thinking, impaired memory ('brain fog')
  • Goitre (may be present, e.g., in Hashimoto's or iodine deficiency)
  • Delayed relaxation phase of deep tendon reflexes
  • Peripheral neuropathy (paraesthesias)
  • Carpal tunnel syndrome

Risk factors

  • Autoimmune thyroid disease (Hashimoto's thyroiditis - most common cause in iodine-sufficient areas)
  • Treatment for hyperthyroidism (Radioactive iodine therapy, Thyroidectomy)
  • External beam radiation to the neck area
  • Iodine deficiency (major cause globally)
  • Certain medications (e.g., Lithium, Amiodarone, Interferon)
  • Pituitary or hypothalamic disease (Secondary/Tertiary hypothyroidism - rare)
  • Congenital hypothyroidism (neonatal screening important)
  • Postpartum thyroiditis

Diagnosis

Clinical assessment

Suspect based on symptoms of slowed metabolism (fatigue, cold intolerance, weight gain, constipation, dry skin, etc.). Assess for goitre, characteristic physical signs. Differential diagnosis: Depression, Chronic fatigue syndrome, Anaemia, Renal failure, Dementia, Normal aging.

Investigations

  • Thyroid Function Tests (TFTs): Elevated TSH is the most sensitive indicator of primary hypothyroidism. Low Free T4 (FT4) confirms overt hypothyroidism. (Subclinical hypothyroidism: Elevated TSH, normal FT4).
  • Thyroid Autoantibodies (Anti-TPO, Anti-Tg): Positive in Hashimoto's thyroiditis.
  • CBC (check for associated anaemia).
  • Lipid profile (cholesterol often elevated).
  • CK (Creatine Kinase): May be elevated (myopathy).

Diagnostic criteria

Clinical symptoms + Elevated TSH + Low FT4 (for overt primary hypothyroidism).

Management

Non-pharmacological management

  • Supportive care.

Pharmacological treatment

  • Thyroid Hormone Replacement:
  • - Levothyroxine (Synthetic T4): Treatment of choice.
  • - Starting dose (Adults): Typically 50-100 mcg PO once daily (lower dose e.g., 25-50 mcg in elderly or those with cardiac disease). Take on empty stomach (e.g., 30-60 min before breakfast) for consistent absorption.
  • - Dose Titration: Adjust dose based on TSH levels checked every 4-8 weeks initially, aiming to normalize TSH (within target range, e.g., 0.5-4.5 mU/L). Increase dose gradually (by 12.5-25 mcg increments).
  • - Maintenance dose: Usually 100-200 mcg daily once TSH stable.
  • - Child: Dose based on age/weight (higher mcg/kg dose than adults). Requires specialist management.
  • - Pregnancy: Increased dose requirements (often by 30-50%). Monitor TSH frequently.
  • - Monitor for drug interactions affecting absorption (e.g., calcium, iron, PPIs - separate dosing).
  • - Treatment is usually lifelong.
  • Iodine supplementation (only if deficiency is the cause).

Monitoring

Monitor TSH levels periodically (every 6-12 months once stable on maintenance dose). Monitor clinical symptoms. Monitor for signs of over-replacement (hyperthyroid symptoms).

Complications

  • Myxoedema Coma (life-threatening severe hypothyroidism - hypothermia, bradycardia, hypoventilation, altered mental status, coma). Requires urgent IV levothyroxine/liothyronine, steroids, supportive care (ICU).
  • Cardiovascular disease (associated with dyslipidemia, hypertension - risk may decrease with treatment).
  • Heart failure (can be caused or worsened by hypothyroidism).
  • Infertility, adverse pregnancy outcomes.
  • Neuropsychiatric symptoms (depression, cognitive impairment).
  • Goitre (if underlying cause leads to it).

Prevention

  • Adequate iodine intake (prevents iodine deficiency hypothyroidism).
  • Neonatal screening for congenital hypothyroidism.

Patient education

  • Explain hypothyroidism and need for lifelong hormone replacement.
  • Correct way to take levothyroxine (empty stomach, consistent timing).
  • Importance of regular TSH monitoring and dose adjustments.
  • Symptoms of under-replacement (hypothyroid) and over-replacement (hyperthyroid) to report.
  • Inform other doctors/pharmacists about levothyroxine use (potential interactions).
  • Reassurance that symptoms improve with adequate treatment.

Uganda-specific notes

Iodine deficiency was historically major cause, Hashimoto's also relevant. TSH and FT4 testing availability may be limited. Levothyroxine is the standard treatment available. Ensure correct dosing and monitoring where possible.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 8, Section 8.1.7

Scroll to Top