Insulin and C-peptide in plasma and tumor of insulinoma patients.

Ohneda, Akira; Sakai, Toshiro; Kobayashi, Takashi; Nihei, Jiro

doi:10.1620/tjem.139.73

Cited by 2 publications

(2 citation statements)

References 24 publications

(11 reference statements)

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“…Immunostaining of the islet cell tumor was positive for glucagon, amylin, and proinsulin but not insulin indicating that it was probably a functional islet cell tumor. The failure to detect insulin immunostaining in the tumor with two different anti-human insulin antibodies and one anti-mouse insulin antibody is troubling, but could be the result of the rapid release of the hormone from the tumor or a molecular variant not detected by the antibodies we used for immunostaining [21,22] . The finding of strongly positive proinsulin immunostaining in the tumor suggests that it was possibly the major peptide secreted by this tumor causing the hypoglycemia; although a serum insulin level of 64 μIU/ml (reference range is < 17 μIU/ml) was inappropriately elevated for a serum glucose level of 64 mg/dl.…”

Section: Discussionmentioning

confidence: 99%

Proinsulinoma causing severe hypoglycemia in a patient with type 1 diabetes mellitus

Bertheau¹,

Herceg

Malgor

et al. 2014

CRCP

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Case presentation: A 49 year male a 35 year history of Type 1 Diabetes Mellitus (T1DM) was evaluated for recurrent episodes of hypoglycemia. After being weaned off of all exogenous insulin, the patient continued to have frequent and severe episodes of hypoglycemia often associated with seizures. Results:During an observed hypoglycemic reaction in our office he was found to have a serum glucose level of 64 mg/dl, a serum insulin level of 64 μIU/ml (reference range is <17 μIU/ml) and a C-peptide level of 0.6 ng/ml (reference range is 0.8 ng/ml -3.1 ng/ml). Serum and urine sulfonylurea levels were negative. During a formal diagnostic 72 hour fast, he developed severe hypoglycemia within four hours of beginning the fast and seized. No diagnostic laboratory studies were obtained during the hypoglycemic event! He underwent surgical exploration, where a 0.8 cm well-differentiated, islet cell tumor was resected. Following resection of the tumor, the spontaneous hypoglycemia resolved, and maintenance exogenous insulin was reinstituted. Histoimmunochemical staining was positive for chromogranin, synaptophysin, amylin, and proinsulin but negative for insulin. Immunostaining of the tumor was also positive for Toll-like receptors-3 (TLR3) and Wnt5a.Conclusion: This is the first case report of a patient with a long history of T1DM who developed a recurrent hypoglycemia due to a proinsulin-secreting islet cell tumor which resolved following its resection.

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Section: Discussionmentioning

confidence: 99%

Proinsulinoma causing severe hypoglycemia in a patient with type 1 diabetes mellitus

Bertheau¹,

Herceg

Malgor

et al. 2014

CRCP

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“…It was reported that gel filtration chromatography of C-peptide extracted from the tumors reveals lower molecular weight fragments in addition to the authentic C-peptide [32]. This suggests that, though our case is rare in that the serum C-peptide levels were extremely low, the C-peptide levels in general might lead clinicians to underestimate autonomous hypersecretion of insulin in insulinoma patients.…”

Section: Discussionmentioning

confidence: 76%

A Case of Secretin-responsive Insulinoma with Low Serum C-peptide Levels

et al. 2007

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Abstract. Insulinoma is the most common cause of fasting hypoglycemia resulting from autonomous insulin hypersecretion. A 59-year-old woman who had previously had an insulinoma and had undergone a partial pancreatectomy was admitted to our hospital because of recurrence of hypoglycemia after 27 years. She had two unusual endocrinological features: 1) the serum insulin response to intravenous secretin injection was not impaired, and 2) the serum C-peptide levels and ratios of serum C-peptide to insulin were relatively low. Two pancreatic tumors were readily detectable by computed tomography (CT) and magnetic resonance imaging (MRI). The selective arterial calcium injection (SACI) test showed a hyperinsulinemic response by calcium administration to the gastroduodenal artery. A partial pancreatectomy was done and her hypoglycemia disappeared. Histology revealed that the tumors were composed of monotonous, small round cells that were positive for both insulin and cathepsin B. As previous in vitro studies have shown that C-peptide can be metabolized within human insulinoma cells by proteolytic cleavage by cathepsin B, our patient's low serum C-peptide levels might have been caused by degradation of C-peptide by cathepsin B. According to the data from the literature, the molar ratio of serum C-peptide to insulin is generally decreased in patients with insulinoma than normal subjects. This case highlights the need for careful interpretation of C-peptide levels and the intravenous secretin injection test in the diagnosis of insulinoma.

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Insulin and C-peptide in plasma and tumor of insulinoma patients.

Cited by 2 publications

References 24 publications

Proinsulinoma causing severe hypoglycemia in a patient with type 1 diabetes mellitus

Proinsulinoma causing severe hypoglycemia in a patient with type 1 diabetes mellitus

A Case of Secretin-responsive Insulinoma with Low Serum C-peptide Levels

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