Somatostatin receptor scintigraphy before and after treatment with somatostatin analogues in patients with thyroid eye disease

Octreotide, a potent synthetic long-acting somatostatin analogue, has been shown to have a beneficial effect in thyroid eye disease (TED). Orbital sci ntigraphy using ocetreoscan-111 is a useful study, which can be used to vis ualize somatostatin-receptor-bearing cells and also to select patients who might benefit from octreotide therapy. One major limitation of this therapy is that the drug must be administered parenterally and used several times daily. Lanreotide, a new somatostatin analogue, has a much longer duration of action in comparison with octreotide, and has recently been found to hav e a beneficial effect in the treatment of thyroid eye disease. The aim of t his study was to investigate the orbital Indium-111-pentetreotide activity after treatment with octreotide and lanreotide in patients with thyroid oph thalmopathy. Fourteen patients were studied. 12 with bilateral and 2 with u nilateral thyroid eye disease, (10 females and 4 males) and all with modera tely severe symptoms of ophthalmopathy. All were treated with antithyroid d rugs and were euthyroid at the time of the study. All patients were investi gated with orbital scintigraphy using octreoscan-111 and selected for study on the basis of a positive octreoscan. Five patients received 30 mg lanreo tide intramuscularly once every 2 weeks over a period of 3 months, and 5 pa tients received octreotide 100 mu g subcutaneously thrice daily for 3 month s. Four patients served as controls and received no treatment. The octreosc an-111 scintigraphy was repeated in all patients 3 months after the first e xamination, The NOSPECS classification and the clinical activity score (CAS ) of thyroid ophthalmopathy were also evaluated before and 3 months after t he initiation of treatment. All patients who received treatment had a negat ive follow-up octreoscan while controls had a positive octreoscan. NOSPECS score and CAS were improved with treatment, but unchanged in control patien ts. The reduced uptake of octreoscan may be the result of blocking of somat ostatin receptors, or reduction in receptor-expressing tissues, downregulat ion of somatostatin receptors in target tissues, or a combination of these factors.