Hypothyroidism and Myxedema Coma Follow-up

Further inpatient care is as follows:

• Admit patients with myxedema coma to ICU.

• Provide supportive ventilatory and hemodynamic management.

• Treat precipitating events (eg, infection).

• Continue rewarming as required.

• Confirm diagnosis with laboratory testing.

• Continue thyroid hormone replacement, and convert to oral therapy when tolerated.

• Clinical improvement should be apparent within 24-36 hours of initiating thyroid hormone replacement.

Potential complications are as follows:

• Treatment-induced congestive heart failure in patients with coronary artery disease

• Myxedema coma

• Increased susceptibility to infection

• Megacolon

• Organic psychosis with paranoia

• Adrenal crisis with vigorous treatment of hypothyroidism

• Hypersensitivity to opiates

• Pericardial effusion and cardiac tamponade ^[12]

The prognosis of hypothyroidism is good with early treatment. However, once the disease has progressed to myxedema coma, the mortality rate may exceed 20% in the treated population. Relapses occur if treatment is discontinued.

The mortality rate in myxedema coma has historically been as high as 80%. Some data suggest that aggressive management and early recognition have improved the mortality rate to 15-20%. However, a more recent observational study was unable to show significant differences in outcome based on replacement therapeutic methods, with a mortality rate remaining high at 40%. ^[13]

The aforementioned study by Ono et al reported that, as revealed through multivariable logistic regression, a higher inhospital mortality rate in myxedema coma was associated with older age and catecholamine use (with or without steroids). ^[7]

A study by Sato et al suggested that in patients with heart failure, those with subclinical hypothyroidism have a worse prognosis, finding a significant increase in the rates of cardiac events and all-cause mortality in heart failure patients in the study with subclinical hypothyroidism compared with those who were euthyroid. ^[14]

A literature review by Chrysant suggested that levothyroxine supplementation for subclinical hypothyroidism in younger persons (specifically, those with a thyroid-stimulating hormone [TSH] level of >4.0 mIU/L) is more effective with regard to cardiovascular disease, heart failure, and mortality than it is in older patients. Chrysant also suggested that such treatment in older patients be individualized according to symptom presence and TSH level and that it commence when TSH levels are 10 mIU/L or above. He also advised that, in order to avoid harmful cardiovascular effects in older persons related to overtreatment, it be administered at low doses in these patients. ^[15]

Patients should be educated about the following:

• Importance of medication compliance

• Need for lifelong treatment

• Watch for signs of infection

• Watch for signs of thyrotoxicity

For patient education resources, see the Endocrine System Center, as well as Thyroid Problems and Myxedema Coma.