The
problem of goitre with particular consideration of goitre
resulting from iodine deficiency (II):
Management of non-toxic nodular goitre and of thyroid nodules
Andrzej Lewinski
Department
of Thyroidology, Institute of Endocrinology, Medical University
of Lódz; Poland.
Department of Endocrinology, Polish Mother's Memorial Hospital
– Research Institute, ódz, Poland.
Key
words:
nodular goitre; single thyroid nodules; diagnostics; treatment
June
7, 2002
Accepted: June 13, 2002
ABSTRACT
The
present opinions on the therapy with L-thyroxine (L-T4) of
non-toxic multinodular, as well as of non-toxic thyroid nodules
are rather divergent. This treatment is based on the suppression
of TSH secretion from the pituitary.
There are no doubts that fine-needle aspiration biopsy (FNAB)
performance is the first and – at the same time –
the most significant diagnostic procedure in the case of thyroid
structural lesions (nodules, goitre, thyroiditis). FNAB performance
should – by all means – precede the beginning of
L-T4 application for the treatment of non-toxic multinodular
goitre or thyroid nodules.
The simplicity, clearness and high efficacy, with comparable
results in each case, are the core of good diagnostic algorithm.
Unfortunately, not all diagnostic algorithms concerning thyroid
nodules and multinodular goitre fulfil these important criteria.
Rather
divergent views have been reported, concerning the application
of levothyroxine (L-T4) preparations in the therapy of single,
non-toxic thyroid nodules and of multinodular nontoxic goitre;
the nature of this treatment is suppression of thyrotropin (TSH)
secretion from the pituitary, while TSH is a significant growth
factor for thyroid follicular cells in vivo [1].
However, both early reports [2], and the latest observations
[3] reveal that TSH is not required for thyroid growth initiation
and promotion. Following this opinion, some reports indicate
that TSH need not be the dominating growth factor, either for
benign or for malignant thyroid tumours [3].
On one hand, the efficacy of L-T4 suppressing effects on nodule
size reduction is not certain, while, on the other, an administration
of thyroid hormones in TSH secretion-suppressing doses may lead
to decrease of bone mineral density, especially in postmenopausal
women [4].
Women with history of either hyperthyroidism or of L-T4 administration
in TSH concentration-suppressing doses (as a therapy commonly
used in the complex treatment of differentiated thyroid cancer
– following total thyroidectomy and 131I application),
should undergo bone mineral density evaluation, especially in
sites with cortical bone prevalence (e.g., hip, forearm) and,
however to a smaller extent, in areas with trabecular bone structure.
It should be emphasized that the thyroid hormone replacement
therapy with maintained normal serum TSH concentration, has
either a minimal or no effect on the bone mineral density (BMD)
at all [4].
L-T4 administration may also be a risk factor of cardiac hypertrophy
[5]. Left-ventricular hypertrophy has been observed as a result
of chronic L-T4 administration in patients with no significant
changes in either heart rhythm or arterial blood pressure or
in left-ventricular systolic function, what suggests a direct,
trophic effect of L-T4 on myocardium [5].
Recently, several prospective studies have been analysed, concerning
the effects of L-T4 administered in TSH-suppressing doses for
at least 6 months, on the sonographically-determined volume
of single benign thyroid nodules [6]. The summary of obtained
results indicates that patients, in whom the nodule volume decreased
by more than 50%, stood for 26.5% in a group of 242 L-T4-administered
patients, while 12.3% only among 171 patients of the control
group, receiving either placebo or no treatment at all. Moreover,
in the control group, there was a higher percent of patients,
presenting with nodular volume increase by more than 50% (17.3%),
when compared with that in the L-T4-receiving group (8.1%).
Zelmanowitz et al., using cumulative metaanalysis, have drawn
a conclusion that treatment with L-T4 preparations was associated
with decreasing volume of thyroid nodules in 17% of patients,
while in other 10% of the patients, L-T4 prevented the increase
in volume of examined nodules [6]. According to the cited authors,
an appropriate management should comprise a 12-month therapy
with L-T4 preparations, administered in suppressive doses to
premenopausal women and men – in whom no cardiovascular
contraindications have been diagnosed; this treatment should
then be continued with slightly smaller doses of L-T4 (relative,
partial or incomplete TSH suppression), if nodular volume has
decreased. Unlike in younger persons, may TSH-suppressive therapy
with use of LT4, when applied in older age, induce undesirable
side-effects, outweighing the actual therapeutic advantages.
Moreover, there is a risk that such therapy may deteriorate
the symptoms resulting from previous, suppression-resistant,
endogenic foci of thyroid hormone production.
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