A 65-year-old woman was admitted to our hospital because of episodes of altered mental status and high blood pressure. Forty days prior to admission, the patient was taken to the emergency department with an altered mental status and hypertension. Her blood pressure was 226/129 mmHg, while her blood glucose level was 48 mg/dL. After that, the patient suffered four similar attacks with high systolic blood pressure more than 200 mmHg as well as lowered plasma glucose less than 70 mg/dL. The patient had Whipple’s triadic signs: hypoglycemic symptoms, low glucose level at the time of the symptoms, and the amelioration of the symptoms after glucose administration. Laboratory tests on admission showed the following values: fasting plasma glucose, 55 mg/dL; immunoreactive insulin, 45.2 µU/mL; and C peptide, 4.4 ng/mL. Enhanced abdominal computed tomography was performed and showed a lesion 15 mm in diameter in the pancreatic body that was strongly enhanced in the arterial phase. Based on the diagnosis of a solitary insulinoma, laparoscopic resection of the pancreatic body and tail was performed. The resected specimen contained a well-circumscribed white round mass, which was pathologically found to be a well-differentiated tumor with amyloid deposition. Immunohistochemical studies showed positive staining for insulin and the neuroendocrine markers synaptophysin and chromogranin A, leading to the diagnosis of the insulinoma. After surgery, the patient’s fasting plasma glucose and immunoreactive insulin normalized to 116 mg/dL and 5.3 µl/mL, respectively. She has not had paroxysmal hypertension since the surgery. Her systolic blood pressure has been maintained at less than 140 mmHg without antihypertensive agents, and mental condition have also clearly stabilized (Figure).
Discussion:
Insulinoma is a rare pancreatic islet cell tumor with an estimated incidence of 0.4 per 100,000 person-years. Hyperinsulinemia accompanying insulin resistance has been reported to be associated with hypertension. However, most of the previous studies showed that there is no association between hyperinsulinemia and hypertension in the setting of insulinoma. Our case exhibited both symptoms of neurologic features due to hypoglycemia and emergent hypertension with systolic blood pressure more than 180 mmHg. These symptoms might have been challenging for the emergent unit to differentiate from cerebrovascular disorders such as cerebral hemorrhage or infarction. The possible etiology of hypertension induced by an insulinoma is catecholamine release in response to hypoglycemia, which may cause acute hypertension through activation of the sympatho-adrenal system. Another hypothesis is that the sodium-retaining effect of insulin may contribute to a rise in blood pressure.
Conclusions:
We herein report a rare case of hypoglycemia-induced paroxysmal hypertension that was ameliorated by the surgical removal of an underlying insulinoma. This case implies that sustained hyperinsulinemia due to insulinoma can be functionally linked to the induction of paroxysmal hypertension.