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Case Reports
. 2025 Jun 27;17(6):e86880.
doi: 10.7759/cureus.86880. eCollection 2025 Jun.

Severe and Prolonged Hypoglycemia Following Adrenalectomy for Pheochromocytoma: A Case Report

Masahiko Kawasumi  1 , Yoshiro Sakamoto  2 , Yuka Tosaka  1 , Yukiko Okazaki  1 , Shoko Furuya  1
Affiliations
Case Reports

Severe and Prolonged Hypoglycemia Following Adrenalectomy for Pheochromocytoma: A Case Report

Masahiko Kawasumi et al. Cureus. .

Abstract

We report a case of a 64-year-old woman with poorly controlled diabetes mellitus who was found to have a left adrenal pheochromocytoma. Despite standard preoperative management including alpha-blockade with doxazosin, the patient developed persistent and severe hypoglycemia immediately following adrenalectomy, requiring high-rate intravenous glucose infusion. Markedly suppressed preoperative urinary C-peptide levels rapidly increased after surgery, indicating reversible beta-cell suppression due to catecholamine excess. Over a 10-year postoperative course, the patient maintained stable glycemic control with dietary therapy alone, demonstrating substantial improvement in glucose metabolism. This case highlights the rare but significant risk of postoperative hypoglycemia even under optimized perioperative conditions, and illustrates the potential for long-term improvement in diabetes following pheochromocytoma resection.

Keywords: adrenal pheochromocytoma; catecholamine excess; glucose metabolism; hypoglycemia; insulin sensitivity; postoperative hypoglycemia; secondary diabetes.

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Conflict of interest statement

Human subjects: Informed consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. Imaging Findings Consistent With Left Adrenal Pheochromocytoma
(A) Iodine-131 metaiodobenzylguanidine (131I-MIBG) scintigraphy showing focal radiotracer uptake in the left adrenal region, consistent with a catecholamine-secreting tumor. (B) Coronal T2-weighted MRI demonstrating a well-circumscribed, hyperintense mass in the left adrenal gland measuring approximately 4.4 cm in diameter (red arrow). (C) Axial T2-weighted MRI confirming the adrenal lesion with high signal intensity and smooth, ovoid morphology (red arrow).
Figure 2
Figure 2. Continuous Glucose Infusion and Blood Glucose Levels After Adrenalectomy
This figure illustrates the continuous glucose infusion rate (gray bars) and corresponding blood glucose levels (blue line) in a patient following adrenalectomy. The red dashed line represents the hypoglycemia threshold (70 mg/dL). The glucose infusion rate is depicted as a continuous, uninterrupted administration, accurately reflecting the clinical course.
Figure 3
Figure 3. Postoperative Changes in 24-Hour Urine C-peptide Excretion
Serial measurements of 24-hour urinary C-peptide levels before and after adrenalectomy. The preoperative value was markedly decreased (25.8 μg/day; reference range: 29.2-167 μg/day), suggesting suppressed endogenous insulin secretion likely due to catecholamine excess. A rapid postoperative increase was observed, peaking on postoperative day 2 (112.0 μg/day), followed by gradual stabilization. This trend supports the reversibility of beta-cell suppression in pheochromocytoma-associated secondary diabetes.
See this image and copyright information in PMC

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