AbstractIn the present study we report a case of thyroglobulin (TGB) measurement interference in a total thyroidectomized and radio-ablated 61-year old woman with papillary thyroid cancer. We investigated possible interference in the measurement of TGB due to discordant TGB in relation to clinical condition during the follow-up period. Serum TGB was measured with the chemiluminescence method using Beckman Coulter Unicel DxI 800 instrument. To investigate possible interference in TGB measurement serial dilutions, polyethylene glycol precipitation (PEG), treatment with heterophile blocking tube (HBT), rheumatoid factor level determination and retesting of TGB with an alternative method were performed. Serial dilutions of the serum sample revealed linearity but a remarkable decrease in TGB in the patient’s serum samples post PEG and post HBT treatments. Also, TGB results under functional sensitivity level obtained with a different method suggested that TGB interference developed due to heterophile antibody presence in the serum sample. The patient had unnecessarily undergone expensive imaging techniques, and invasive procedures such as lymph node fine needle aspiration biopsy, before the analytical interference was suspected by the clinician. This report illustrates the importance of early communication and close collaboration between clinicians and laboratorians in order to avoid unnecessary clinical intervention.
Comparison of Thyroglobulin Concentrations Measured by Two Immunoradiometric Assay
