Things We Do for No Reason™: Routine Thyroid-Stimulating Hormone Testing in the Hospital

Inspired by the ABIM Foundation’s Choosing Wisely^® campaign, the “Things We Do for No Reason^™” (TWDFNR) series reviews practices that have become common parts of hospital care but may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent clear-cut conclusions or clinical practice standards but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion.

A 62-year-old woman with chronic obstructive pulmonary disease (COPD) presents to the emergency department with shortness of breath, wheezing, and altered mental status (AMS). She is diagnosed with an acute COPD exacerbation with hypercarbic respiratory failure and is treated with nebulized albuterol/ipratropium and intravenous methylprednisolone. The hospitalist orders basic admission laboratory tests, including a thyroid-stimulating hormone (TSH) test for completeness, although she suspects that the patient’s AMS is secondary to hypercapnia. Upon review, the TSH level is low (0.12 mIU/L). A free T4 (FT4) level is ordered and returns mildly low (0.6 ng/dL). Somewhat puzzled, the hospitalist wonders if the patient might have central hypothyroidism and if further testing is needed.

Thyroid disease has a prevalence in adults of 4.6% and 1.3% for hypo- and hyperthyroidism, respectively.¹ Severe manifestations of thyroid disease are rare, with an annual incidence of 0.2 per 100,000² for thyroid storm and 1.08 per 1,000,000³ for myxedema coma in adults. Although most thyroid disease is mild and managed in the outpatient setting, inpatient thyroid testing is common, with evidence suggesting that 21%-100% of internal medicine admissions receive thyroid testing.^4-7

Despite the rarity of severe thyroid disease, symptomatic hypo- or hyperthyroidism is often included in the differential diagnosis for a multitude of presenting problems to the hospital. Providers may view TSH as a simple means to rule out thyroid illness and narrow the diagnostic differential, particularly given the speed and availability of testing. In addition, cultural norms may encourage the routine assessment of thyroid function as a part of a thorough inpatient evaluation, even when alternative diagnoses could explain the patient’s symptoms.⁸ In many hospitals, TSH is included in emergency department laboratory panels and hospital admission order sets (sometimes as a preselected default), which can significantly influence prescriber ordering.^4,6,7,9

Hardwick et al. conducted structured interviews with primary care providers to explore the factors contributing to high thyroid testing variability. Among the potential contributing factors identified were fear of a missed diagnosis, as well as the complexity and poor integration of electronic health records, which makes repeat testing easier than requesting outside records.¹⁰ Most importantly, providers may assume that all abnormal results indicate clinically relevant thyroid dysfunction despite differences between TSH test characteristics in inpatient vs outpatient settings.¹¹