Short fasting test as a reliable and effective tool to diagnose insulinoma.

PURPOSE: The diagnosis of insulinoma can be challenging, requiring documentation of hypoglycaemia associated with non-suppressed insulin and C-peptide, often achieved during a prolonged 72 h fast performed in inpatient setting. Our goal is to predict weather a shorter outpatient fasting test initiated overnight and prolonged up until 24 h could be a sensitive method for diagnosing insulinoma. METHODS: We conducted a retrospective monocentric study on subjects admitted to our Unit of Endocrinology from 2019 to 2022 for clinical suspicion of insulinoma and underwent the short fasting test. A comparison between the short test group and the group of subjects who underwent the standard prolonged fasting test (from 2003 to 2018) has also been performed. The short fasting test was initiated by the patient overnight at home and proceeded the following day in outpatient setting (Day Hospital). As in the standard protocol, symptoms and capillary blood glucose (CBG) were strictly monitored. Venous blood was drawn for glycaemia, insulin and C-peptide at admission and at established intervals, in case of symptoms of hypoglycaemia or if CBG ≤ 45 mg/dl, when the fast would be suspended. RESULTS: The final sample consisted of 37 patients, with mean age of 44.5 ± 12.6 years (17-74). Short and standard tests were performed in 15 and 22 subjects, respectively. Diagnostic values for insulinoma were observed in 12 patients: in 5/15 who underwent the short fasting test, in 6/22 who underwent the prolonged test and in 1 patient who was initially negative on the short test and subsequently showed diagnostic values during the prolonged test. The diagnosis of insulinoma was achieved in 11/12 cases within 24 h of the beginning of the fast (91.7%). CONCLUSIONS: A short fasting test could be a valid, sensitive and reliable first-line workup in diagnosing insulinoma.

Cortisol Deficiency in Lenvatinib Treatment of Thyroid Cancer: An Underestimated Common Adverse Event.

Background: Lenvatinib treatment has shown a significant improvement in progression-free survival in patients with metastatic, progressive, radioiodine-refractory differentiated thyroid cancer, although its use is associated with considerable toxicity. Fatigue is one of the most frequent adverse events (AEs). It has been reported that adrenal insufficiency (AI) may be involved in lenvatinib-related fatigue. In our study, we assessed the pituitary/adrenal axis before and during treatment, and the possible involvement of AI in lenvatinib-related fatigue. This was done to clarify the incidence, development, and time course of AI during lenvatinib treatment. Methods: We studied 13 patients who were selected for lenvatinib therapy. Adrenal function was evaluated by measuring cortisol and adrenocorticotropic hormone (ACTH) levels and through the ACTH (250 µg) stimulation test. Results: During treatment, seven patients (54%) developed AI. High levels of ACTH were observed in accordance with the diagnosis of primary AI (PAI). By evaluating the first ACTH test, before starting lenvatinib treatment, we found that patients with <646.6 nmol/L cortisol peak had an increased risk of developing PAI during lenvatinib treatment. Fatigue was observed in 11 patients (84.6%) during lenvatinib treatment. Cortisone acetate treatment induced an improvement in fatigue in six of seven patients (85.7%) in the PAI group, without the need to change the lenvatinib dosage. Conclusions: PAI may be considered one of the most common AEs associated with lenvatinib. Our data strongly suggest that PAI could be involved in lenvatinib-associated fatigue, particularly in patients with extreme fatigue. In this context, early diagnosis of PAI is essential, especially since glucocorticoid replacement therapy can induce a significant improvement in fatigue, without the need to reduce the dosage of lenvatinib. However, further studies are required to confirm these preliminary findings.