A new study suggests that screening for thyroid-stimulating hormone (TSH) is done both too often and unnecessarily when patients are admitted for psychiatric evaluation.

Researchers at Waterbury Hospital (Waterbury, CT, USA) conducted a chart review for 98 patients (83% of whom had a previous psychiatric history) to examine the appropriateness of measuring TSH levels in patients under evaluation because of behavioral disturbances, even if there are no other clinical signs or symptoms suggesting thyroid dysfunction. In all, TSH screening was ordered for 66.3% of the adult patients admitted to an inpatient psychiatry unit during one eight-week period.

The results showed that 97% of those tests turned out to be within the normal range, with only two patients whose TSH levels were outside the normal range, of whom one was elevated and one was low. When the admission diagnoses among patients who had undergone TSH screening and those who had not were considered, depression was identified in 26 and 7 patients, respectively. There was no difference in the length of hospital stay in the TSH group and the non-TSH group, with a mean stay of 9.5 days. Nine patients in the TSH group and eight in the non-TSH group had also undergone screening within the previous six months. The study was presented as a poster session at the midyear clinical meeting of the American Society of Health-System Pharmacists (ASHP), held during December 2011 in New Orleans (LA, USA).

“Routine TSH screening should not be done for patients with a long history of psychiatric disease, as was the case in most of our patients, and especially if a previous level has been obtained recently,” said lead author and study presenter Kelly Shepard, PharmD. “We have many patients with frequent readmissions. The test can be useful for patients with a first admission, but is unnecessary in patients with a 10-year history of disease.”

Both hyper- and hypothyroidism are recognized as potential contributors to psychiatric illness, with psychosis being specifically included in the diagnostic criteria for thyroid storm. In addition, the US Endocrine Society (Chevy Chase, MD, USA) guidelines state that thyrotoxicosis, with a TSH level below 0.01 mU/L, can cause alterations in psychiatric and neuropsychological function. Depression also has been linked with thyroid dysfunction, particularly among patients with previously recognized thyroid abnormalities.
 

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