Do you want to participate in a clinical study as a healthy control? - Risk or benefit?

Abstract

A healthy woman volunteered to participate as “healthy control” in a study. An increased level of procalcitonin (PCT) was detected and remained elevated on follow-up measurements. As calcitonin levels were elevated as well, thyroid ultrasound was performed which revealed nodes in both thyroid lobes, one of them showing metabolic activity in positron emission tomography-computed tomography scan. To exclude a malignant thyroid cancer despite the negative findings in a fine needle aspiration the patient underwent thyroidectomy and a medullary thyroid carcinoma (MTC) was detected in the right lobe. MTC is a rare endocrine tumor with a poor prognosis once having spread, therefore early detection remains a priority for the outcome. Screening parameter is serum calcitonin, in absence of infection the pro-hormone PCT can be used as a screening parameter as well with high sensitivity.

Keywords: Medullary thyroid cancer; Procalcitonin; Thyroid nodes; Endocrinology; Public health; Healthy control

Core tip: A lady participating as healthy control in a study was found to suffer from a medullary thyroid cancer, a type of cancer in total surgical removal before the tumor has spread is the most important prognostic factor. The difficulty is the low diagnostic accuracy of ultrasound and procalcitonin-computed tomography scan, as well as the limitations of fine needle aspiration in a patient with several nodules. This case illustrates the consequences of volunteering as a “healthy control” in a clinical study. While early detection of the MCT was possible in our patient it paid off for her, but abnormal test results may also cause harm to patients if being false positive and leading to invasive procedures.