Paediatrics: Acquired hypothyroidism
A relatively common condition with an estimated prevalence of 0.1–0.2% in the population.
A relatively common condition with an estimated prevalence of 0.1–0.2% in the population. The incidence in girls is 5–10 times greater than in boys.
Acquired hypothyroidism may be due to a primary thyroid problem or indirectly to a central disorder of hypothalamic-pituitary function.
Primary hypothyroidism (raised TSH; low T4/T3)
- Autoimmune (Hashimoto’s or chronic lymphocytic thyroiditis).
- Iodine deficiency: most common cause worldwide.
- Subacute thyroiditis.
- Drugs (e.g. amiodarone, lithium).
- Post-irradiation thyroid (e.g. bone marrow transplant—total body irradiation).
- Post-ablative (radioiodine therapy or surgery).
Central hypothyroidism (low serum TSH and low T4)
Hypothyroidism due to either pituitary or hypothalamic dysfunction.
- Intracranial tumours/masses.
- Post-cranial radiotherapy/surgery.
- Developmental pituitary defects (genetic, e.g. PROP-1, Pit-1genes): isolated TSH deficiency; multiple pituitary hormone deficiencies.
The symptoms and signs of acquired hypothyroidism are usually insidious and can be extremely difficult to diagnose clinically. A high index of suspicion is needed.
- Goitre: primary hypothyroidism.
- Increased weight gain/obesity.
- Decreased growth velocity/delayed puberty.
- Delayed skeletal maturation (bone age).
- Fatigue: mental slowness; deteriorating school performance.
- Constipation: cold intolerance; bradycardia.
- Dry skin: coarse hair.
- Pseudo-puberty: girls—isolated breast development; boys—isolated testicular enlargement.
- Slipped upper (capital) femoral epiphysis: hip pain/limp.
Diagnosis is dependent on biochemical confirmation of hypothyroid state.
- Thyroid function tests: high TSH/low T4/low T3.
- Thyroid antibody screen. Raised antibody titres:
- antithyroid peroxidase;
- TSH receptor (blocking type).
- Oral Levothyroxine (25–200 micrograms/day).
- Monitor thyroid function test every 4–6mths during childhood.
Monitor growth and neurodevelopment.