Comparative diagnostic value of the calcium-pentagastrin test versus the tolbutamide test in a patient with a somatostatinoma

Calcitonin Stimulation Tests: Rationale, Technical Issues and Side Effects: A Review

Calcitonin (CT) stimulation tests have great value and could help to: differentiate thyroid causes of elevated CT apart from non-thyroid sources, determine whether the patients with slightly elevated basal CT could/could not be candidates for surgery, and indicate the right moment for prophylactic thyroidectomy in children with MEN syndromes when with normal basal CT. This triggered the requests for development of CT stimulation tests, taking into consideration their safety and aimed us to write a systematic review of literature regarding the rationale, technical issues, and side effects of CT stimulating tests used for diagnosis of MTC. After a thorough review of the literature, we classified the reported side effects by severity, as defined by United States Food and Drug Administration. A statistical analysis was performed using IBM SPSS Statistics version 20. Various side effects were noticed during stimulation tests that differ by intensity, duration and severity, depending on types of substances and protocols used. The side effects after pentagastrin test were significantly more severe than those reported after calcium stimulation test (p=0.0396). There are also significant gender-specific differences in side effects induced by stimulation tests. In conclusion, we recommend performing Ca CT stimulation test when needed, considering preventive evaluation of some clinical, instrumental, and biochemical aspects of each patient. Precise instructions should be followed before a stimulation test and furthermore continuous cardiac monitoring is essential during and after the test to minimize the possibility of a serious event.

Duodenal somatostatinoma: a case report and review of 31 cases with special reference to the relationship between tumor size and metastasis

Somatostatinomas are rare functioning neoplasms usually arising in the pancreas and duodenum. We report a case of somatostatinoma in a 42-year-old male with neither neurofibromatosis nor somatostatinoma syndrome. A large tumor in the descending duodenum had given rise to multiple lymph node metastases. An additional 31 duodenal somatostatinoma cases were also reviewed. Most originated in the descending part of the duodenum, with the ampulla and peri-ampullary area as the most common sites (60%). Frequent manifestations were abdominal pain (25%), jaundice (25%), or cholelithiasis (19%), the latter two reflecting obstruction of the bile duct by tumors. Only two cases showed a possible somatostatinoma syndrome (6%). The tumors with metastases, lymph nodes (10) and liver (2), were significantly larger than average than those without (2.91 +/- 1.49 cm vs 1.36 +/- 0.71 cm, P < 0.05). With a cut-off point of 2.0 cm, diagnostic accuracy for metastasis was 77.78% with 87.50% specificity and 63.64% sensitivity. The smallest tumor with metastases was 0.8 cm and the largest without metastases was 3.0 cm. These results indicate that duodenal somatostatinomas are malignant by nature and the risk of metastasis significantly increases with tumors larger than 2.0 cm.