Goiter and impairment of thyroid function in acromegalic patients: Basal evaluation and follow-up

Aims: We evaluated morphological, biochemical and cytological thyroid param eters in acromegalic patients, investigated before and after treatment for acromegaly. Patients: 28 acromegalics were investigated before and, in 18 c ases, after 2-7 years of therapy. Fourteen patients were from areas of mode rate iodine deficiency in Southern Italy. One patient underwent thyroidecto my before entering this study. Results: 19 patients were euthyroid (FT4: 17 .7 +/- 0.8 pmol/l and FT3 4.6 +/- 0.2 pmol/l), but TSH was undetectable in 5/19. Among them, TRH-stimulated TSH increase was absent/impaired or exagge rated/delayed in 9 and one cases, respectively. Decreased FT3 and/or FT4 Va lues with low/normal TSH values were detected in 7 cases; TRH-stimulated TS H response was absent/impaired in 2 patients and exaggerated/delayed in ano ther two. Increased free T4 and free T3 concentrations with undetectable TS H levels were found in one. Two euthyroid patients had high TPOAb levels. G oiter was diagnosed in 21 cases and nodules were found in 14/21. Tc-99 scin tiscan showed "cold" areas in 13/14 cases and a "hot" nodule in the hyperth yroid patient. Acromegalics from iodine deficient areas showed a not signif icant increase of prevalence of goiter (86 vs. 71 %) and of mean thyroid vo lume (35 +/- 7 vs. 28 +/- 4 ml, NS), compared to others. Thyroid Volume (TV ) did not correlate with CH, IGF-1 and TSH levels, the area under the curve of insulin-increase during OGTT, the age of patients or the duration of ac romegaly. Fine needle aspiration biopsy (FNAB), performed in 11/14 patients with nodular goiter, showed colloid nodules in 8 cases, hyperplastic nodul es in 2 and an adenomatous nodule in one. Neurosurgery, radiotherapy or med ical treatment for acromegaly induced a significant decrease of mean CH and IGF-1 levels (21.5 +/- 8.5 vs. 12.9 +/- 9.6 ng/ml, p < 0.005 and 747 +/- 9 4 vs. 503 +/- 88 ng/ml, p < 0.02, respectively), but both GH and IGF-1 valu es normalized only in 3 cases. No significant variation of mean TSH levels was found. Although TV normalized in 3 patients, ultrasound evaluation show ed a not significant decrease of mean TV and no changes in the diameter and number of nodules. FNAB was unchanged. Conclusions: Our results suggest th at, despite no correlation between serum GH and IGF-1 levels and thyroid vo lume being found, a decrease in serum GH and IGF-1 levels has favourable ef fects on thyroid status.