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Persani et
al., Milan, Italy and Stanford, CA, USA, studied
phosphodiesterase (PDE) activity in normal thyroid tissue and in
tissue of autonomous thyroid adenomas (ATA). PDE’s degrade
cAMP and thus attenuates intracellular cAMP mediated signalling.
In many ATA’s so-called constitutive activation of the cAMP
pathway is found due to mutations in the TSHR gene or the
Gs-alpha gene. The authors report increased PDE activity in such
adenoma’s and philosophied that this increased activity
counterbalanced the constitutive activation of the cAMP pathway.
This increased PDE activity can thus be considered as an
adaptation phenomenon in this dysregulated system of activation.
(Comment: As the nodules were still autonomous, this adaptive
effect is apparently insufficient for complete counterbalancing
the dysregulation.)
Agretti et al., Pisa, Italy, studied in total 15 patients with 1, 2, or multiple hyperfunctioning nodules (adenoma/hyperplastic nodules) in a toxic multinodular goitre. In 6/15 adenoma they found different constitutive activating mutations in the TSH receptor gene. Different mutations were found in multiple hyperfunctioning nodules in the same goitre and these gain-of-function mutations were present not only in thyroid adenoma but also in hyperplastic nodules (lacking a capsule). Reske, Leipzig, Germany, screened 14 patients with cold thyroid nodules (CTN) for the level of NA+/I–symporter (NIS) expression within the cold nodule. NIS expression was measured at the level of NIS mRNA. In 10/14 CTN’s, NIS expression was decreased >65%, and in 6/10 expression was <10%. In 2/14 a reduction of expression of 42 and 32% was shown, while 2/14 had normal NIS mRNA expression. NIS expression correlated with scintigraphic phenotype of CTN. (Comment: These results confirm on a molecular basis the early findings of Field JB. and Larsen PR. et al., J Clin Invest 52:2404, 1973, who demonstrated a transport defect of iodide in non-functioning nodules in human thyroid glands.) Capula et al., Catanzaro, Italy, evaluated the effect of L-T4 treatment on prevention of postoperative goitre recurrence in patients from an area with moderate iodine deficiency (goitre prevalence 37%, urinary iodine excretion 65.6 ± 52.1 µg/l). In total 61 patients (50 F, 15-69 years) with non-toxic nodular or multinodular goitre were studied. 32/61 Underwent lobectomy, 22/61 subtotal thyroidectomy, and 8/61 nodulectomy. 37/61 Patients received L-T4 therapy and 24/61 served as controls. Median follow-up was 4 years. In the L-T4 group no recurrences occurred in 32/37 (86.5%) and in de control group 23/24 showed recurrence either multinodular (n = 16) or uninodular (n = 7). These differences were highly significant and the authors conclude that in iodine deficient areas routine postoperative L-T4 treatment is to be recommended. (Comment: T4 treatment in patients operated for nodular goitre is still controversial. This controversy mainly concerns patients from iodine sufficient areas. The results of this study show a dramatic effect of T4 treatment on a short-term basis in patients from an iodine deficient area. The authors carefully checked that after operation ultrasound scanning of the thyroid showed only a normal remnant and no nodules and, using this technique, any recurrence or absence of recurrence of nodularity was evaluated. The question arises if supplementation with iodine after operation also suppresses recurrence rate). |
