Management of infants with hyperthyroidism

Positive or unknown TRAb with normal thyroid function in an asymptomatic infant requires follow up age 4 weeks and 2-3 months.
Positive or unknown TRAb with abnormal thyroid function requires assessment of clinical features and likely treatment with antithyroid drugs (ATD).

The aim of treatment in symptomatic infants is to facilitate return to biochemical euthyroid state.

Treatment should be initiated at the onset of symptoms to avoid short and long term complications.

There is no clear evidence that biochemical hyperthyroidism in the absence of symptoms should be treated.

This should be a decision made by the relevant consultant and endocrine team.

Recommendations

Biochemical hyperthyroidism in a symptomatic infant:

Start carbimazole 0.750mg/kg/day in single or divided doses.
Use propylthiouracil 2.5 to 5mg/kg twice daily instead of carbimazole if there are significant side effects with carbimazole.

Biochemical hyperthyroidism in asymptomatic infant:

Consider carbimazole: 0.2-0.750mg/kg/day in single or divided doses (but this may not be necessary if the infant remains asymptomatic).

Signs of sympathetic hyperactivity:

Consider adding Propranolol 2mg/kg/day in 3 to 4 divided doses
(+/- admission to hospital).

Haemodynamically unstable:

Carbimazole
Mild	Serious
Transient liver transaminitis Transient leucopenia Skin rashes GI upset Arthralgia, myalgia	Agranulocytosis – fever, mouth ulcers, neutropenia Liver injury Vasculitis Stevens-Johnson syndrome