Paediatrics: Hyperthyroidism (thyrotoxicosis)

Hyperthyroidism (thyrotoxicosis)

·Thyrotoxicosis: refers to the clinical, physiological, and biochemical findings that result when the tissues are exposed to excess thyroid hormones.

·Hyperthyroidism: denotes those conditions resulting in hyperfunction of the thyroid gland leading to a state of thyrotoxicosis.

Causes of thyrotoxicosis

Due to hyperthyroidism

·  Excessive thyroid stimulation:

·  Graves’s disease

·  Hashimoto’s disease

·  neonatal (transient) thyrotoxicosis

·  pituitary thyroid hormone resistance (excess TSH)

·  McCune–Albright syndrome

·  hCG-secreting tumours

·  Thyroid nodules (autonomous):

·  toxic nodule/multinodular goitre

·  thyroid adenoma/carcinoma

Not due to hyperthyroidism

·  Thyroiditis:

·  subacute

·  drug-induced

·  Exogenous thyroid hormones

Clinical features (all causes)

Thyrotoxicosis may be associated with the following symptoms:

·hyperactivity/irritability;

·poor concentration; altered mood; insomnia;

·heat intolerance/fatigue/muscle weakness/wasting;

·weight loss despite increased appetite;

·altered bowel habit—diarrhoea;

·menstrual irregularity;

·sinus tachycardia; increased pulse pressure;

·hyperreflexia; fine tremor;

·pruritis.

Investigations

·Thyroid function tests (serum): raised T4 and T3; suppressed TSH.

·Thyroid antibodies: antithyroid peroxidase; anti-thyroglobulin; TSH receptor antibody (stimulatory type).

·Radionucleotide thyroid scan: increased uptake (Graves’s disease); decreased uptake (thyroiditis).