From the Guidelines
Inpatient management of hypothyroidism should prioritize the severity of symptoms and the patient's ability to perform activities of daily living (ADL), with treatment guided by TSH and free T4 levels, as outlined in the ASCO guideline update 1. For asymptomatic patients with TSH levels between 4.5 and 10 mIU/L, continuation of immune checkpoint inhibitor (ICPi) therapy with monitoring of TSH every 4-6 weeks is recommended 1.
- In cases of moderate symptoms (G2), ICPi therapy may be continued or held until symptoms resolve, with consideration of endocrine consultation and thyroid hormone supplementation for symptomatic patients or those with TSH levels persistently above 10 mIU/L 1.
- For severe symptoms (G3-4), including medically significant or life-threatening consequences, ICPi therapy should be held, and hospital admission with inpatient endocrinology consultation is necessary for rapid hormone replacement and supportive care, including IV levothyroxine dosing and steroids if indicated 1. Key considerations in the management of inpatient hypothyroidism include:
- Monitoring TSH and free T4 levels to guide treatment and adjust hormone replacement therapy as needed
- Addressing precipitating factors such as infections and managing hypothermia with passive rewarming
- Administering stress-dose glucocorticoids until adrenal insufficiency is ruled out, given the potential for coexisting conditions
- Careful monitoring during treatment initiation to mitigate risks of unmasking adrenal insufficiency or precipitating cardiac events in vulnerable patients.
From the FDA Drug Label
The levothyroxine in Levothyroxine Sodium Tablets, USP is intended to replace a hormone that is normally produced by your thyroid gland. The adequacy of therapy is determined by periodic assessment of appropriate laboratory tests and clinical evaluation In adult patients with primary (thyroidal) hypothyroidism, serum TSH levels (using a sensitive assay) alone may be used to monitor therapy.
The recommended management for inpatient hypothyroidism is to replace the hormone with levothyroxine and monitor therapy by periodic assessment of laboratory tests, such as serum TSH levels, and clinical evaluation.
- Key considerations:
- Monitor serum TSH levels at 6-8 week intervals until normalization
- Perform clinical and biochemical monitoring every 6-12 months
- Adjust levothyroxine dosage as needed to maintain normal TSH levels
- Be aware of potential interactions with other medications, such as iron and calcium supplements, and antacids, which can decrease levothyroxine absorption 2 3
From the Research
Management of Inpatient Hypothyroidism
The management of inpatient hypothyroidism involves the use of levothyroxine replacement therapy. The following are key points to consider:
- The starting dose of levothyroxine varies depending on the patient's age, weight, and underlying medical conditions 4, 5, 6.
- For most patients, therapy can be initiated with a full replacement dosage of 1.6 micrograms/kg body weight, which is usually 75 to 100 micrograms/day for women and 100 to 150 micrograms/day for men 6.
- However, patients older than 60 years or with known or suspected ischemic heart disease should start at a lower dosage of levothyroxine (12.5 to 50 mcg per day) 5.
- The goal of levothyroxine replacement therapy is to normalize the serum thyroid-stimulating hormone (TSH) concentration 4, 6.
- The daily maintenance dose of levothyroxine varies widely between 75 and 250 microg, and assessment of the appropriate dose is by assay of TSH and free thyroxine (fT4) 7.
Special Considerations
- Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% up to nine doses per week, followed by monthly evaluation and management 5.
- Patients with persistent symptoms after adequate levothyroxine dosing should be reassessed for other causes or the need for referral 5.
- Early recognition of myxedema coma and appropriate treatment is essential 5.
- The availability of intermediate tablet strengths of levothyroxine in the 25-75 mcg range may facilitate precise and effective dose titration of levothyroxine and may also enable convenient maintenance regimens based on a single levothyroxine tablet daily, to support adherence to therapy 8.
Monitoring and Adjustment
- Laboratory tests should not be done earlier than 6 weeks after a dose adjustment, as a new equilibrium is reached after approximately 6 weeks 7.
- With a stable maintenance dose, an annual check-up usually suffices 7.
- Dose adjustments may be necessary in pregnancy and when medications are used that are known to interfere with the absorption or metabolism of levothyroxine 7.