Distribution of Functional Status of Thyroid Nodules and Malignancy Rates of Hyperfunctioning and Hypofunctioning Thyroid Nodules in Germany

Abstract

Aim Thyroid scintigraphy enables the depiction of the functional status of thyroid nodules (TNs) with both, 99mTc-pertechnetate and 123Iodine. The functional status is relevant for diagnostic procedures for the differentiation of benign and malignant TNs. The aim of this study was to examine the current frequencies of hyper-, hypo- and isofunctioning TNs in Germany and to estimate the risk of malignancy with regard to functional status. Methods In 11 study centers, a minimum of 100 nodules per center were consecutively enrolled between July 2019 and April 2020. Inclusion criteria were: newly diagnosed nodule, nodule’ size of 10 mm or more, thyroid scintigraphy. Exclusion criteria were: completely cystic TNs, patients with prior radioiodine therapy or thyroid surgery. The risk of malignancy was estimated for hyper- and hypofunctioning TNs. Results Overall, 849 patients (72 % women) with 1262 TNs were included. Patients’ age ranged from 18 to 90 years. Most TNs were hypofunctioning (n=535, 42%) followed by isofunctioning TNs (n=488, 39%) and hyperfunctioning TNs (n=239, 19%). When only TNs with a maximum size of 2 cm or more were considered the rate of hyperfunctioning and hypofunctioning TNs increased (to 27% and 49%) while isofunctioning TNs decreased. Only one of all hyperfunctioning TNs was malignant. In hypofunctioning nodules, the malignancy rate was estimated at 10%. Conclusion In Germany, the proportion of hyperfunctioning TNs is approximately 20% and increases in larger TNs to up to 27%. Due to the low risk of malignancy in hyperfunctioning TNs, no further procedures to rule out malignancy are necessary. The risk of malignancy of hypofunctioning TNs is significantly higher. Thus, a thyroid scintigraphy is a useful diagnostic tool in Germany.

Update on Calcitonin Screening for Medullary Thyroid Carcinoma and the Results of a Retrospective Analysis of 12,984 Patients with Thyroid Nodules

“…Patients with nodules ≥1 cm on ultrasonography received thyroid scintigraphy, according to the practice guideline of the European Association of Nuclear Medicine [ 21 ] regardless of the current TSH value since in iodine deficiency regions such as Germany, the TSH value has only a low predictive value for the functional status of a thyroid nodule [ 22 , 23 , 24 ]. In selected cases of scintigraphically non-autonomous nodules, a fine-needle biopsy was performed.…”

“…Depending on the degree of Ctn elevation, patients with confirmed elevated Ctn values either had a follow-up basal Ctn measurement 3-12 months later and/or a stimulation test, or they were immediately referred for surgery (see the flow chart, Figure 1). Patients with nodules ≥1 cm on ultrasonography received thyroid scintigraphy, according to the practice guideline of the European Association of Nuclear Medicine [21] regardless of the current TSH value since in iodine deficiency regions such as Germany, the TSH value has only a low predictive value for the functional status of a thyroid nodule [22][23][24]. In selected cases of scintigraphically non-autonomous nodules, a fine-needle biopsy was performed.…”

Integrated Diagnostics of Thyroid Nodules

“…Therefore, although autonomous nodules are almost invariably accompanied by decreased TSH levels (i.e., <0.1-0.4 mUI/L) when the iodine supply is adequate, the bulk of autonomous tissue may be insufficient to suppress the TSH level in iodine-depleted thyroids, especially in the early phases of autonomy. As a consequence, different indications are given in current clinical guidelines with a thyroid scan recommended when the TSH level is low or low to normal in the USA (iodine-repleted country), whereas a Na[ 99m Tc]TcO 4 scan is recommended in all people with a nodule greater than 10 mm, independently of the TSH level in Germany (iodine-deficient country) [5,39,55,56] Consequently, high iodine concentrations (e.g., regular use of products rich in iodine) may reduce the quality of a functional image. For this reason, any "excess" iodine intake should be avoided before scintigraphy or it should be postponed for several (i.e., 1-3) to many (i.e., 6 or more) months in patients with severe iodine contamination due to radiological contrast media administration or amiodarone therapy, respectively [55].…”

“…Thyroid nodules are more common in countries with iodine-deficient populations, and in women compared to men (ratio 4:1), and their prevalence increases with age and body mass index [1][2][3][4][5].…”

2023 European Thyroid Association Clinical Practice Guidelines for thyroid nodule management

“…Thyroid scintigraphy should be performed when serum TSH is suppressed or at the lower normal limits. Of note, in areas of current or previous iodine deficiency, hyperfunctioning nodules may also be seen in individuals with normal TSH, meriting the use of thyroid scintigraphy ( 97 , 98 ).…”