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Thyroid Disorders
Guideline-orientated Diagnosis of Thyroid Nodules
Ralf Paschke,
1
Enrico Papini
2
and Hossein Gharib
3
1. Professor of Internal Medicine and Endocrinology, III Medical Department, University of Leipzig; 2. Professor of Endocrinology, University of Rome
‘La Sapienza’ Medical School; 3. Professor of Medicine, Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine
Abstract
Thyroid nodules are very common. Their aetiology is due to the interaction between genetic and environmental factors. In 2006, two major
society-sponsored guidelines and one major consensus statement for thyroid diagnosis and management were published by the American
Association of Clinical Endocrinologists/Associazione Medici Endocrinologi (AACE/AME), the American Thyroid Association (ATA) and the
European Thyroid Association (ETA). A careful review of these guidelines reveals that despite many similarities, significant differences are
also present, likely reflecting differences in practice patterns, interpretation of existing data and availability of resources in different regions.
The methodology of the guidelines is similar, but a few differences in the rating scales make a rapid comparison of the strength of both
evidence and recommendations difficult for use in current clinical practice. Some recommendations are based mostly on expert opinion.
The same recommendation may be based on different evidence; on the other hand, sometimes the same evidence may induce a different
recommendation. A survey performed during an interactive symposium at the 32nd annual meeting of the ETA in Leipzig, Germany, was
carried out to investigate whether these guidelines were able to affect the divergent management strategies for thyroid nodules that have
previously been documented. The thyroid nodule guidelines obviously provide useful information and recommendations for practice and
have a positive impact on patient care; however, guidelines should be considered as suggestions rather than a rigid formula for practice.
With further accumulating evidence, these guidelines will need revision and updating.
Keywords
Thyroid nodule, diagnosis, treatment, guidelines, evidence-based
Disclosure: The authors have no conflicts of interest to declare.
Received: 27 April 2009 Accepted: 10 July 2009
Correspondence: Ralf Paschke, III Medical Department, University of Leipzig, Ph.-Rosenthal-Str. 27, D-04103 Leipzig, Germany. E: pasr@medizin.uni-leipzig.de
Aetiology, Epidemiology and Risks In areas not affected by nuclear fall-out, the annual incidence of
Thyroid nodules are very common. Moreover, with the increasing use thyroid cancer has been reported to range between 1.2 and 2.6 cases
of sensitive imaging techniques, an increasing proportion of thyroid per 100,000 in men and 2.0 and 3.8 cases per 100,000 in women, with
nodules are now detected incidentally. A prospective study higher incidences in countries such as Sweden, France, Japan and the
comparing clinical examination and ultrasound showed that 46% of US.
7
An increase of thyroid cancer incidence from 3.6 per 100,000 in
nodules >1cm detected by ultrasound escaped detection by clinical 1973 to 8.7 per 100,000 in 2002 has recently been reported in the US.
8
examination.
1
Autopsy and prospective ultrasound studies in North A similar increase of thyroid cancer incidence from 1983 to 2000 was
America detected asymptomatic thyroid nodules in 50 and 67%, reported in France,
9
and the incidence of thyroid cancer in Germany
respectively.
2,3
A population study in Germany – a previously iodine- in 2002 was 6.7 and 3.2 per 100,000 women and men, respectively.
10
deficient and currently borderline iodine-sufficient country – However, most of these increases in thyroid cancer incidence are due
detected thyroid nodules by ultrasound in 20% of the population to an increased detection of small papillary cancers.
8,9
20–79 years of age. The prevalence increased with advancing age to
52 and 29%, respectively, for women and men 70–74 years of age.
4
In autopsy studies, clinically silent thyroid papillary microcarcinomas
(<1cm diameter) have been reported in up to 36% depending on the
According to current knowledge, the aetiology of thyroid nodules can number of serial sections.
11
Most autopsy studies report incidences
be summarised as outlined in Figure 1 (modified from Krohn et al.
5
ranging from 6 to 11%.
12–14
A comparison of these papillary
and Krohn et al.
6
). Susceptibility to developing a thyroid nodule or microcarcinoma incidence rates in autopsy studies with the incidence
goitre mainly in response to iodine deficiency is genetically rates for clinically apparent papillary carcinomas strongly suggests
determined. In genetically susceptible individuals with maladaptation that most papillary microcarcinomas will not lead to clinically
to iodine deficiency, the increased thyroid epithelial cell proliferation apparent thyroid carcinomas. Moreover, these data suggest that
and the increased production of H
2
O
2
will lead to an increased rate histological evaluation of resected thyroid tissue will often detect
of mutagenesis; depending on which gene is hit, this will lead to papillary microcarcinomas with an unlikely clinical relevance. A
small clones of hot or cold thyroid cells, which will then give rise to follow-up study of papillary microcarcinomas over a nine-year period
hot or cold thyroid nodules or, less frequently, thyroid carcinomas. demonstrated no metastases in patients with tumours <0.8mm.
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