Welcome back. Thanks for joining me on this discussion of insulinomas under the section of
general surgery. As a reminder, endocrinopathies in general, whether it’s in a section of
medicine or surgery are incredibly high-yield for the USMLE examinations. Let’s start discussing insulinomas.
Insulinomas result in autogenous insulin secretion usually associated with a pancreatic islet cell tumor.
The main finding is hypoglycemia. Symptoms of hypoglycemia include sweating, dizziness,
confusion, and palpitations. You’ve probably had episodes of hypoglycemia yourself and
it’s an unforgettable feeling. Also remember that multiple endocrine neoplasias, all three types,
are incredibly high-yield. Let’s review the multiple endocrine neoplasia type 1. They consist of
parathyroid tumors, pituitary tumors, and specific to our topic right now, pancreatic tumors.
They contain gastrinomas and insulinomas. On routine laboratory values, the chemistries
and the CBCs are unlikely to be very helpful. However, high serum insulin levels despite low fasting
glucose is almost absolutely necessary for the diagnosis of insulinoma. Here’s a schematic
of the distribution of the functional neuroendocrine tumors of pancreas. Remember that
insulinomas and gastrinomas are both categorized as neuroendocrine functional tumors
of the pancreas. Here’s a depiction of an upper endoscopy with an endoscopic ultrasound.
Oftentimes, this is one of the most helpful modalities to locate the actual insulinoma or
neuroendocrine tumors of the pancreas in general. This procedure is performed by doing
a routine EGD with a special probe that contains an ultrasound probe at the end of the tip.
Here’s a cross-sectional imaging, a CT abdomen/pelvis demonstrating insulinoma. Note on the
image that the insulinoma is in the mid body of the pancreas. At surgery, this is a high definition
laparoscopic view. Notice on the image here that the fat pad in the middle of the screen
depicts the fat overlying the pancreas. As you can see, the pancreas is exposed and the insulinoma
can be enucleated. I’d like to pose a question to you. What is factitious hypoglycemia?
I’ll give you a second to think about it. Factitious hypoglycemia results from exogenous insulin
administration. In clinical scenario, it’s classically associated with medical professionals
such as doctors or nurses. It results in hypoglycemia, hyperinsulin, but unlike actual insulinomas,
the patient actually has a normal to low C-peptide level. Very important clinical pearl: factitious
hypoglycemia can be differentiated based on the C-peptide levels. So, in patients with chronic
hypoglycemia or symptoms of insulinoma, make sure you get an insulin level as well as a C-peptide level.
Once again, as a high-yield topic, the C-peptide is what differentiates an insulinoma versus
exogenous insulin administration. Thank you very much for joining me on this discussion of insulinomas.