Normal reference values for thyroid uptake of technetium-99m pertechnetate for the Namibian population

Abstract

Objective: Historically, changes in normal thyroid uptake values for iodine have been reported in different geographical areas. These changes have been linked to geographical and chronological fluctuations in dietary iodine intake in different populations. Namibia is a country with mixed ethnicity, with access to dietary iodine in table salt. Despite historical reports on deviating normal thyroid uptake values (emphasising the importance of establishing local normal reference values), the relevant Namibian authorities have never revised these reference values, nor have local reference values been established. The aim of this study was to establish the normal reference values for thyroid uptake of technetium-99m pertechnetate in the Namibian population.Design: Participants who were considered to be euthyroid completed a questionnaire designed to exclude individuals with thyroid pathologies, as well as those with renal or heart disease. Settings and subjects:The study cohort consisted of 76 participants (58 women and 18 men), ranging in age from 39-81 years. The participants were of mixed ethnicity, consisting of Hereros, Ovambos, Damaras, Namas, Coloureds, Caucasians and other (non-Namibian immigrants), and were from Windhoek, Namibia. Studies were performed at the Windhoek Central Hospital.Outcome measures: Blood was drawn for thyroid hormone assessment. Participants were then given 100 MBq of technetium-99m pertechnetate intravenously, and their percentage thyroid uptake recorded after 20 minutes. Results:In this study, thyroid-stimulating hormone, triiodothyronine, and thyroxine levels were found to be 1.7 µIU/ ml, 4.9 pmol/ml and 10.3 pmol/ml, respectively. Analysis of the empirical data showed that the normal reference uptake value for technetium-99m pertechnetate in the studied population ranged between 0.04% and 2.40%.The fifth and 95 th percentiles for pertechnetate uptake were 0.15% and 1.69%, respectively. Conclusion:These results provide new evidence which supports the importance of periodical evaluation of normal thyroid uptake reference values for technetium-99m pertechnetate.Peer reviewed.

The utility of technetium-99m pertechnetate thyroid scintigraphy assessing thyroid/salivary ratio as an alternative to thyroid uptake percentage in evaluation of thyroid function, with establishing normal reference values of both parameters: single Egyptian center study

“…It has been shown in the literature that normal values of Tc99m-pertechnetate thyroid uptake depend on the technique used and on the dietary intake of iodide. Each laboratory should, therefore, establish its own normal values [11,24,25]. To the best of our knowledge, we were the first who tried to establish a reference range of TcU and TSR in our institution in Egypt.…”

“…[31], Hamunyela et al . [11] and Ramos et al . [5] (0.2–2.0%, 0.15–1.69% and 0.4–1.5%, respectively).…”

“…In the current study, sex and age have no influence on both TcU and TSR among control and euthyroid patients, this was in line with Hamunyela et al . [11] who reported that sex has no influence on the TcU among euthyroid individuals. On the other side, Marvin et al .…”

“…The normal reference values for thyroid uptake of technetium-99m (TC99m) pertechnetate and radioactive iodine in euthyroid persons change with the geographical location and may change from one decade to the next. Throughout history, fluctuations in the normal reference values have been documented [11]. According to Nelson et al .…”

“…The normal reference values for thyroid uptake of technetium-99m (TC99m) pertechnetate and radioactive iodine in euthyroid persons change with the geographical location and may change from one decade to the next. Throughout history, fluctuations in the normal reference values have been documented [11]. According to Nelson et al [12], it has been demonstrated that it is important to establish normal thyroid uptake values on a regional basis because normal limits vary within different geographical areas.…”