FRI360 A Protracted Course Of Worsening Adrenergic And Neuroglycopenic Symptoms Due To Delay In Diagnosis Of Insulinoma
Authors: Karca Ayla , Lai William , Naidoo Shiva , Saladi Lakshmi N , Jameson Brian C 
Published: October 2023

Disclosure: A. Karca: None. W. Lai: None. S. Naidoo: None. L.N. Saladi: None. B.C. Jameson: None.

A 33-year-old Hispanic male presented with altered mental status, witnessed seizure and hypoglycemia (capillary BG 40mg/dL). Patient and family reported multiple episodes of symptomatic hypoglycemia and progressively worsening adrenergic and neuroglycopenic episodes with altered mental status requiring hospital admissions and evaluation for endogenous hyperinsulinemia in the past several months prior to admission. Patient was admitted to the ICU. Laboratory workup revealed documented hypoglycemia (venous BG 45mg/dL) and inappropriate insulin (17uU/mL, n3-25uU/mL), c-peptide (2.7ng/mL, n0.8-4.2 ng/mL) and pro-insulin (38.3 pmol/L, n&lt;18.8 pmol/L) levels. Sulfonylurea and meglitinide screens were negative. Patient required continuous dextrose infusion as well as octreotide, with enteral feeding, to maintain BG &gt;70mg/dL. Abdominal US, multiple CT scans, endoscopic US failed to locate source of endogenous hyperinsulinemia. Multi-discipline discussion among ICU team, Endocrinology, Interventional Radiology (IR), and Surgery considered MRI versus IR-guided selective arterial calcium stimulation (SACS) vs PET-CT NETSPOT with Ga-68 Dotatate, which had been ordered, but unable to be arranged prior to this admission. Ultimately, MRI with pancreatic protocol revealed 3.5cm exophytic solid mass arising from the tail of the pancreas and patient underwent laparoscopic hand-assisted distal pancreatectomy and splenectomy, with intraoperative ultrasound to confirm the location of the mass. Histologic examination revealed a well-differentiated neuroendocrine tumor. Chart review revealed documented hypoglycemia as far back as eight years prior to this admission, although no further results were available from that time to confirm endogenous source. Possible explanations for delay in diagnosis include patient health literacy, inaccessibility of outpatient testing, limitations of testing modalities, and access to staff skilled in more specialized testing, like PET-CT NETSPOT and SACS. Localizing techniques are divided into pre-operative and intra-operative, with pre-operative techniques further divided into non-invasive and invasive modalities. First line pre-operative testing includes US and CT, which have widely varying sensitivity depending on size and location of the tumor. MRI can have better sensitivity for smaller and distal tumors. PET-CT NETSPOT with Ga-68 Dotatate, has very high sensitivity and specificity in limited studies. If not localized with non-invasive modalities, SACS is an invasive modality with high sensitivity and specificity. Although insulinomas are a rare neuroendocrine tumor with challenging diagnostic workup, higher clinical suspicion with early biochemical workup, patient education, referral to endocrinology, better accessibility of diagnostic testing will help lead to timely diagnosis and management.

Presentation: Friday, June 16, 2023