Endocrinology fellow Medical University of South Carolina Charleston, South Carolina, United States
Introduction : Endogenous hyperinsulinemic hypoglycemia cases are challenging to diagnose, and determining the etiology is imperative for treatment. We present a patient with hypoglycemia and pancreatic mass, and the workup required to reach the diagnosis of noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS).
Case(s) Description : A 23-years-old female with history of pituitary resection for macroadenoma and central adrenal insufficiency (AI) was admitted to the hospital for workup of recurrent hypoglycemia. She reported overnight and mid-day blood glucose values to 40mg/dL associated with lightheadedness, shaking, sweating and an episode of syncope. Symptoms resolved with glucose tablets. Despite taking supraphysiologic dose of hydrocortisone for possible AI induced hypoglycemia, hypoglycemic events persisted. The results of a 72-hours fast suggested insulinoma with the exception of beta-hydroxybutyrate levels. A subsequent dotatate scan reported a 1.8cm soft tissue nodule along the pancreatic tail near the splenic hilum likely a splenule, but unable to rule out insulinoma. Abdominal MRI followed by endoscopic ultrasound reported the nodule to be a splenule with low suspicion for insulinoma. For further tissue characterization, heat-damaged RBC scan was performed confirming the mass to be a splenule. Invasive workup was required with selective arterial calcium stimulation test (SACST) identifying the body and tail of the pancreas to have abnormally high insulin secretion. Patient was diagnosed with NIPHS and she underwent distal pancreatectomy with splenectomy. Insulin and c-peptide levels immediately post-op were normal and elevated at 24-hours. Insulin administration was unnecessary and patient was discharged on physiologic hydrocortisone. Shortly after, supraphysiologic hydrocortisone was resumed for hypoglycemia and patient subsequently developed daytime hyperglycemia to 300mg/dL along with overnight hypoglycemia. She is requiring insulin and will start evening diazoxide for nighttime hypoglycemia. Her glucose management remains a challenge.
Discussion : This case demonstrates the difficulty in determining the etiology of hyperinsulinemic hypoglycemia particularly when a pancreatic mass is identified but not consistent with an insulinoma. In addition, heat-damaged RBC scan is a lesser known modality that is highly specific for detecting accessory spleen. If initial imaging is unable to differentiate between a splenule and insulinoma, a negative heat-damaged RBC scan supports an insulinoma diagnosis and can prevent invasive testing with SACST or endoscopic ultrasound. Lastly, recurrent hypoglycemia has been reported after partial pancreatectomy for NIPHS making it a challenge to treat.
