Objectives: The aim of the study was to evaluate the normal reference values for thyroid uptake using Technetium-99 m (Tc-99 m) pertechnetate.
Methods: Sixty-seven euthyroid patients with primary hyperparathydism who underwent parathyroid imaging with Tc-99 m pertechnetate between January 2012 to April 2014 at the Nuclear Medicine department, Newcastle upon Tyne Hospitals was studied. Electronic medical records and biochemical thyroid function tests were reviewed to confirm that all patients were not on medication or supplements that could affect thyroid function and they were both clinically and biochemically euthyroid within 6 months of the scan. Thyroid uptake values were determined by the dual tracer subtraction protocol.
Results: Median and interquartile uptake range of Tc-99 m pertechnetate in euthyroid patients were 0.9% and 0.51.4% respectively. The normal reference range in the study population was 0.22.0%. Thyroid uptake inversely correlated with age in the female (r=−0.40, P=0.04), male (r=−0.50, P=0.04), and whole group (r=−0.40, P=0.002).
Conclusion: The normal reference range for Tc-99 m pertechnetate uptake was found to be less than that presently adopted in our institution (1.03.5%). However, it was comparable to that observed in recent studies from geographically distant populations. Periodic, location-specific evaluation of normal uptake values is advocated to increase diagnostic precision in thyroid disease.