Metastatic proinsulin-secreting tumor: a rare cause of persistent hypoglycemia.
This case emphasizes the diagnostic and management challenges of proinsulin-secreting neuroendocrine tumors, where standard treatments may not be effective.
Where it sits
this study against the rest of the octreotide corpusSummary and findings
This case report describes a 47-year-old female with metastatic large-cell neuroendocrine carcinoma presenting with severe hypoglycemia. Despite treatment with high-dose corticosteroids, glucagon, diazoxide, and octreotide, glycemic control was not achieved. The patient ultimately required total parenteral nutrition with concentrated dextrose due to persistent hypoglycemia.
Abstract
Proinsulin-secreting neuroendocrine tumors (NETs) are a rare cause of severe hypoglycemia, characterized by normal or low insulin levels and disproportionate elevations of proinsulin. Clinical features and optimal management of unresectable cases remain poorly defined, in part due to such few cases described in the literature. We describe a 47-year-old female with metastatic large-cell neuroendocrine carcinoma who presented with obstructive jaundice and was incidentally found to have profound, asymptomatic fasting hypoglycemia. Initial insulin and C-peptide levels were within reference ranges, but proinsulin concentrations were markedly elevated. The patient developed recurrent, refractory hypoglycemia requiring high-dose corticosteroids, glucagon, diazoxide, octreotide, and ultimately central-line infusion of 70% concentrated dextrose via total parenteral nutrition. Glycemic control could not be achieved despite maximal medical therapy, and the patient experienced rapid clinical deterioration leading to comfort-focused hospice management. This case highlights the diagnostic challenges of proinsulin-driven hypoglycemia and underscores the need for earlier recognition and improved treatment pathways for patients with proinsulin-secreting NETs.
Background
Proinsulin-secreting neuroendocrine tumors (NETs) are infrequently reported causes of severe hypoglycemia, often presenting with normal or low insulin levels. Prior literature indicates that these tumors can lead to significant clinical challenges due to their rarity and the complexity of their management. This study is important as it sheds light on the diagnostic and therapeutic difficulties faced in unresectable cases of proinsulin-secreting NETs.
Methods
This is a case report of a 47-year-old female with metastatic large-cell neuroendocrine carcinoma. The patient presented with obstructive jaundice and profound fasting hypoglycemia. Treatment involved high-dose corticosteroids, glucagon, diazoxide, octreotide, and total parenteral nutrition. No specific duration or dose of octreotide was detailed in the abstract.
Results
The patient exhibited markedly elevated proinsulin levels while insulin and C-peptide levels remained within reference ranges. Despite aggressive treatment, including octreotide, glycemic control was not achieved, leading to a rapid clinical deterioration.
Interpretation
This case adds to the limited literature on proinsulin-secreting NETs, emphasizing the diagnostic challenges and the lack of effective treatment options. The findings suggest that while octreotide is commonly used in neuroendocrine tumors, its efficacy in managing proinsulin-driven hypoglycemia remains questionable. The small sample size and the nature of a single case limit the generalizability of the conclusions drawn.
Key findings
- Proinsulin concentrations were markedly elevated.
- Insulin and C-peptide levels were within reference ranges.
- The patient required high-dose corticosteroids, glucagon, diazoxide, and octreotide.
- Glycemic control could not be achieved despite maximal medical therapy.
Limitations
- Single case report limits generalizability.
- Lacks quantitative data on treatment efficacy.
- No long-term follow-up reported.
- Industry funding not disclosed.