Predicting Therapeutic Radioiodine Activity in Graves’ Disease Using Thyroidal Technetium-99m (Tc-99m) Uptake Values

Muhammad Adil; Fida Hussain; Zaigham Salim Dar; Muhammad Atif; Muhammad Asad; Naimat Ullah Khan

doi:10.51253/pafmj.v76iSUPPL-5.10424

Authors

Muhammad Adil Department of Nuclear Medicine, Armed Forces Institute of Pathology/National University of Medical Sciences (NUMS), Rawalpindi Pakistan
Fida Hussain Department of Nuclear Medicine, Armed Forces Institute of Pathology/National University of Medical Sciences (NUMS), Rawalpindi Pakistan
Zaigham Salim Dar Department of Nuclear Medicine, Armed Forces Institute of Pathology/National University of Medical Sciences (NUMS), Rawalpindi Pakistan
Muhammad Atif Department of Nuclear Medicine, Armed Forces Institute of Pathology/National University of Medical Sciences (NUMS), Rawalpindi Pakistan
Muhammad Asad Department of Nuclear Medicine, Armed Forces Institute of Pathology/National University of Medical Sciences (NUMS), Rawalpindi Pakistan
Naimat Ullah Khan Department of General Medicine, Pak Emirates Military Hospital/National University of Medical Sciences (NUMS), Rawalpindi Pakistan

DOI:

https://doi.org/10.51253/pafmj.v76iSUPPL-5.10424

Keywords:

Graves’ Disease, Radioiodine Uptake, Radioiodine Therapy, Tc-99m Uptake

Abstract

Objective: To estimate 24-hour radioiodine uptake in patients with Graves' disease using 20-minute Tc-99m uptake values for calculating radioiodine therapeutic dose.

Study Design: Prospective observational study.

Place and Duration of Study: Nuclear Medical Centre, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Mar 2022 to Mar 2023.

Methodology: A total of 131 patients with Graves’ disease who were referred to our center for radioiodine therapy (RAIT) were selected prospectively. Patients were explained pre-requisites, procedure, and precautionary measures in detail, and informed written consent was obtained. All patients underwent 24-hour radioiodine uptake (RAIU24hrs) and 20-minute Tc-99m uptake (TcU20min) measurements after oral ingestion of radioiodine (RAI) and intravenous injection of Tc-99m, respectively. Logarithmic regression analysis was done to correlate RAIU24hrs and TcU20min values. A p-value of less than 0.05 was considered significant.

Results: Of 131 patients, 89(67.9%) were female, while 42(32.1%) were male, with a mean age of 46.93±13.39 years. The mean TcU20min was 18.93±12.08% while the mean RAIU24hrs was 62.68±13.93%. Logarithmic regression analysis showed a significant correlation (p<0.001) between RAIU24hrs and TcU20min, which is described by following equation: Estimated RAIU24hrs = 13.99 x ln (TcU20min) + 25.93; R2 = 0.898.

Conclusion: RAIU24hrs can be predicted from TcU20min, thus providing an alternative, simple, cost-effective, and convenient method for therapeutic radioiodine dose calculation.

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