Initial Levothyroxine Dosing in Extreme Hypothyroidism

Dosing Considerations Based on Patient Characteristics

For patients without risk factors, full replacement can be estimated using ideal body weight at approximately 1.6 mcg/kg/day, according to the Journal of Clinical Oncology guidelines 1
For patients older than 70 years and/or frail patients with multiple comorbidities, start with a lower dose of 25-50 mcg/day and titrate gradually, as recommended by the Journal of Clinical Oncology 1

Monitor TSH every 6-8 weeks while titrating hormone replacement to goal of TSH within the reference range, as suggested by the Journal of Clinical Oncology 1
FT4 can be used to help interpret ongoing abnormal TSH levels on therapy, as TSH may take longer to normalize, according to the Journal of Clinical Oncology 1
Once adequately treated, repeat testing every 6-12 months or as indicated for a change in symptoms, as recommended by the Journal of Clinical Oncology 1

Serum TSH concentration should be monitored every 6-8 weeks during pregnancy and the levothyroxine dose modified as needed, as suggested by JAMA guidelines 2
The requirement for levothyroxine in treated hypothyroid women frequently increases during pregnancy, according to JAMA 2

For subclinical hypothyroidism with TSH >10 mIU/L, levothyroxine therapy is reasonable, as recommended by JAMA guidelines 3
For subclinical hypothyroidism with TSH between 4.5-10 mIU/L, routine treatment is not recommended unless the patient is symptomatic, according to JAMA guidelines 3

Overtreatment can lead to subclinical hyperthyroidism, which may occur in 14-21% of individuals treated with levothyroxine, as reported by JAMA 3
Development of a low TSH on therapy suggests overtreatment or recovery of thyroid function, and dose should be reduced or discontinued with close follow-up, as recommended by the Journal of Clinical Oncology 1
Myxedema coma is a life-threatening emergency requiring admission and a high level of care, according to the Journal of Clinical Oncology 1