Assess cardiac conditions before initiating treatment to decrease risk of ischemic heart disease exacerbation.

Use doses lower than those used for overt hypothyroidism. Start with 12.5 to 25 mcg of l-thyroxine and use lower doses in older patients.

Monitor TSH levels regularly to reach goal of 1 to 2 µU per mL (1 to 2 mU per L).

When the appropriate replacement dose is achieved, obtain follow-up TSH determinations every six to 12 months.