From the Guidelines
For a patient with hypothyroidism, the key parameters to monitor include TSH and FT4 levels, which should be checked every 4-6 weeks in asymptomatic patients, and more frequently in symptomatic patients, as recommended by the 2021 ASCO guideline update 1. When monitoring these patients, it's essential to consider the grading of hypothyroidism, which can range from mild (G1) to severe (G3-4) symptoms.
- For G1 patients, TSH and FT4 levels should be monitored every 4-6 weeks, and ICPi therapy can continue with routine care.
- For G2 patients, TSH levels should be monitored every 6-8 weeks while titrating hormone replacement, and FT4 can be used to help interpret ongoing abnormal TSH levels on therapy.
- For G3-4 patients, ICPi therapy should be held until symptoms resolve, and endocrine consultation is recommended to assist with rapid hormone replacement. It's also crucial to monitor for symptoms of both under-treatment and over-treatment, as well as medication adherence to levothyroxine.
- Tracking body weight, heart rate, and blood pressure periodically is also important, as hypothyroidism can affect cardiovascular function.
- Additionally, monitoring cholesterol levels annually and tracking menstrual cycles in women can help identify potential issues related to thyroid dysfunction. Overall, regular monitoring of TSH and FT4 levels, as well as other key parameters, is essential for proper management of hypothyroidism and preventing potential complications, as supported by the 2021 ASCO guideline update 1.
From the FDA Drug Label
Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation. In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status In patients with hypothyroidism, assess the adequacy of replacement therapy by measuring both serum TSH and total or free-T4.
The key parameters to monitor in a patient with hypothyroidism are:
- Serum TSH levels: every 6 to 8 weeks after any change in dosage, and every 6 to 12 months in stable patients
- Total or free-T4 levels: to assess the adequacy of replacement therapy
- Clinical evaluation: to assess the patient's clinical status and response to therapy 2