An audit of thyroid function testing in acutely ill patients at a South African academic hospital

BACKGROUND: Non-thyroidal illness syndrome (NTIS) can be defined as the presence of abnormal thyroid function in the absence of primary thyroid dysfunction and is associated with acute illness. Thyroid function testing is generally not advised in the critically ill patient. Thyroid-stimulating hormone (TSH) measurement is the preferred screening test for thyroid disease, but results may be misleading and variable in the setting of critical illness. OBJECTIVES: To describe the pattern of requests for TSH testing in patients admitted to the emergency department and intensive care units at Tygerberg Hospital, Cape Town, South Africa. METHODS: A retrospective, descriptive (observational) study was conducted over a 6-month period to determine the number of requests for TSH testing received for patients admitted to the emergency department and intensive care units. RESULTS: A total of 1 139 requests for TSH testing were received from the emergency department and intensive care units, of which 166 were excluded. Of the 973 requests evaluated, 14% yielded abnormal results. The majority (79.4%) of the abnormal TSH results were most likely attributed to NTIS. Follow-up TSH results after 6 - 8 weeks were available in only 18% of cases with abnormal TSH levels at initial presentation. CONCLUSION: We found that TSH testing was often requested in critically ill patients, but that most results were either normal or indicative of NTIS. Follow-up testing of abnormal TSH results was rarely performed. We recommend continued education of junior clinicians regarding thyroid function testing in critically ill patients. CONTRIBUTIONS OF THE STUDY: This study describes the requesting pattern for TSH tests in patients admitted to the emergency department and intensive care unit at Tygerberg Hospital, South Africa. The findings emphasise the importance of prudent thyroid function testing in critically ill patients and follow-up in suspected cases of non-thyroidal illness syndrome.