Abstract
Aim Thyroid scintigraphy enables the depiction of the functional status of thyroid nodules
(TNs) with both, 99m Tc-pertechnetate and 123 Iodine. 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.
Keywords Hyperfunctioning thyroid nodules - Hypofunctioning thyroid nodules - Thyroid scintigraphy
- Risk of malignancy