Hypothyroid patients with high pre-hospitalization TSH levels are at risk of suffering adverse outcomes, suggests a study published in the Journal of Clinical Endocrinology and Metabolism.¹

In this retrospective study, researchers from the University of Chicago analyzed data from 43,478 patients who had been hospitalized from January 2008 through December 2015. Of these, 8873 had primary hypothyroidism; a little more than half (~54%) of these were being treated with levothyroxine; some patients were on liothyronine or desiccated thyroid extract. Hypothyroid patients tended to be older and have more comorbid conditions such as diabetes, chronic kidney disease, and rheumatologic diseases. Women participants were more likely to be hypothyroid.

The hypothyroid patients were categorized into four on the basis of TSH levels before hospitalization: low (< 0.40 mIU/L), normal (0.40-4.50 mIU/L), intermediate (4.51-10.00 mIU/L) and high (> 10.00 mIU/L). The length of stay (LOS), in-hospital mortality and readmission outcomes were the main outcome measures.

Results showed that euthyroid patients were at significantly lower risk of dying during hospital stay (relative risk 0.46); their probability of rehospitalization at 90 days was also lower (relative risk 0.92).

Patients with high TSH levels (>10.00 mIU/L) prior to their hospital admission had a longer duration of hospitalization (+1.2 days) compared to those without hypothyroidism. They were at nearly 50% higher risk of readmission at 30 days with relative risk of 1.49 and were also 43% more likely to be hospitalized again at 90 days (relative risk 1.43). However, the hospital outcomes did not differ between patients with low or intermediate TSH levels and matched controls who did not have hypothyroidism.

These findings focus attention to the high prevalence of suboptimal treatment of hypothyroidism. Patients with good treatment compliance are more likely to have TSH levels within the required range. They also showed that compared to those without hypothyroidism, the undertreated hypothyroid patients, even weeks or months prior to hospital admission, were at a greater risk of adverse outcomes including longer hospitalizations as well as rehospitalizations, which according to the authors “has not been shown previously”. Therefore, patients who are going in for elective surgery or planned admissions should have the dose of their thyroid hormone replacement therapy adjusted to achieve optimal TSH levels prior to hospital admission.

Reference

1. Ettleson MD, et al. Suboptimal thyroid hormone replacement is associated with worse hospital outcomes. J Clin Endocrinol Metab. 2022 Apr 26:dgac215. doi: 10.1210/clinem/dgac215