["Block and replace" of sodium levothyroxine therapy]

Area of Science:

• Endocrinology
• Internal Medicine
• Pharmacology

Background:

• Graves disease is an autoimmune disorder causing hyperthyroidism.
• Lithium therapy for bipolar disorder can influence thyroid function.
• Methimazole monotherapy is a common initial treatment for hyperthyroidism.

Observation:

• A 65-year-old patient with Graves disease and bipolar disorder developed hypothyroidism on high-dose methimazole.
• The patient's autoimmune condition did not remit with monotherapy.
• A switch to a "block and replace" regimen (reduced methimazole with levothyroxine) was initiated.

Findings:

• The "block and replace" regimen rapidly normalized thyroid hormone levels.
• Significant improvement in the patient's clinical symptoms was observed.
• This therapeutic strategy proved effective in managing hyperthyroidism and its complications.

Implications:

• The "block and replace" regimen is a viable alternative to anti-thyroid drug monotherapy for Graves disease.
• This approach may be particularly useful in selected patients requiring careful thyroid hormone management.
• Optimized treatment strategies can improve clinical outcomes in complex endocrine cases.