Should we treat Subclicinical thyrotoxicosis?

    Subclinically thyrotoxic patients are defined as those with "no symptoms", but suppressed TSH <0.03; and normal fT4 and fT3 values.

   For:

Potential benefits of preventing onset of AF and osteoporosis

   Against:

Possible over-treatment of asymptomatic patients who are unlikely to progress to frank thyrotoxicosis , with economic issues and health implications of suppressing free hormone levels and of the treatment modality itself (e.g.: carbimazole). The lack of long term evidence for benefit from treatment at present makes this a controversial area.    

Should we treat Subclicinical hypothyroidism?

Subclinically hypothyroid patients are defined as those with "no symptoms", but raised TSH >6.0 (varies with labs); and normal fT4 and fT3 values.

    For: 

Potential for Improved lipid profile, cardiovascular performance, prevention of weight gain and improvement of subtle symptoms not attributed to the biochemical disturbance per say, argue for early institution of replacement with thyroxine.

    Against: 

There is a lack of evidence for benefits from long term replacement , with economic implications of thyroxine institution. There are also concerns of thyroxine over-replacement with production of a subclinically thyrotoxic state.

Is radioiodine safe in thyrotoxic patients with eye disease?

A study in 1998  by Bartalena et al. compared outcomes in patients with thyroid eye disease who were treated differently. Deterioration of TAO occurred in:

• 15% of patients treated with radioiodine alone;
• 3% of patients treated with antithyroid drugs;
• 0% of patients treated with radioiodine and corticosteroids.

Thus if radioiodine is the best treatment option for an individual patient with thyroid eye disease, ensure that adequate steroid cover is provided.

Bartalena L, Marcocci C, Bogazzi F et al. Use of corticosteroids to prevent progression of Graves' ophthalmopathy after radioiodine therapy for hyperthyroidism. NEJM 1989; 321:1349-52.

What is the evidence for benefits of combined replacement of T3 and T4 over thyroxine alone?