Octreotide in hyperinsulinism

Octreotide Causing Hyperkalemia: A Case Report and Review of the Literature

Octreotide, a synthetic analog of somatostatin, is widely utilized for its inhibitory effects on various hormones, including growth hormone, insulin, and glucagon. Its applications span conditions such as acromegaly, carcinoid tumors, and gastrointestinal bleeding due to its ability to reduce portal venous pressure. Additionally, it serves a crucial role in nuclear medicine imaging and the management of hepatorenal syndrome. We report a case of a 44-year-old man with type 2 diabetes mellitus (T2DM) and stage 5 chronic kidney disease (CKD), not yet on hemodialysis, who presented with persistent severe hypoglycemia. Despite multiple oral glucose administrations, his blood glucose levels remained critically low. The patient was treated with octreotide for sulfonylurea-induced hypoglycemia. However, he developed hyperkalemia as a side effect of octreotide treatment. Traditional therapies for sulfonylurea-induced hypoglycemia often involve intravenous and oral dextrose and glucagon, which may lead to recurrent hypoglycemia due to their stimulatory effects on insulin release. Octreotide directly inhibits insulin release from the pancreas, thus preventing rebound hypoglycemia. However, its administration in patients with renal impairment poses a risk of hyperkalemia due to its suppression of insulin-mediated cellular potassium uptake, and it should be used with caution. This case highlights the potential for life-threatening hyperkalemia induced by octreotide in non-dialysis CKD patients. Physicians must be vigilant about this side effect, particularly in patients with underlying renal impairment. Close monitoring of potassium levels and appropriate management strategies are essential to ensure the safe use of octreotide. This case aims to raise awareness and contribute to a better understanding of octreotide-induced hyperkalemia in CKD patients.

Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia

Hyperinsulinaemic hypoglycaemia (HH) is a biochemical finding of low blood glucose levels due to the dysregulation of insulin secretion from pancreatic β-cells. Under normal physiological conditions, glucose metabolism is coupled to β-cell insulin secretion so that blood glucose levels are maintained within the physiological range of 3.5-5.5 mmol/L. However, in HH this coupling of glucose metabolism to insulin secretion is perturbed so that insulin secretion becomes unregulated. HH typically occurs in the neonatal, infancy and childhood periods and can be due to many different causes. Adults can also present with HH but the causes in adults tend to be different. Somatostatin (SST) is a peptide hormone that is released by the delta cells (δ-cells) in the pancreas. It binds to G protein-coupled SST receptors to regulate a variety of location-specific and selective functions such as hormone inhibition, neurotransmission and cell proliferation. SST plays a potent role in the regulation of both insulin and glucagon secretion in response to changes in glucose levels by negative feedback mechanism. The half-life of SST is only 1-3 min due to quick degradation by peptidases in plasma and tissues. Thus, a direct continuous intravenous or subcutaneous infusion is required to achieve the therapeutic effect. These limitations prompted the discovery of SST analogues such as octreotide and lanreotide, which have longer half-lives and therefore can be administered as injections. SST analogues are used to treat different forms of HH in children and adults and therapeutic effect is achieved by suppressing insulin secretion from pancreatic β-cells by complex mechanisms. These treatments are associated with several side effects, especially in the newborn period, with necrotizing enterocolitis being the most serious side effect and hence SS analogues should be used with extreme caution in this age group.

Peptide receptor radionuclide therapy with 177Lu-DOTA-TATE as a promising treatment of malignant insulinoma: a series of case reports and literature review

INTRODUCTION

Insulinomas are a rare type of pancreatic neuroendocrine tumours characterized by insulin hypersecretion. They are considered malignant when metastases are present. Traditional therapies often promote only temporarily symptomatic relief and may be associated with severe adverse effects. There is scarce experience in treating malignant insulinomas with peptide receptors radionuclide therapy (PRRNT).

PATIENTS AND METHODS

We describe PRRNT results in four patients with inoperable malignant insulinomas with poorly controllable hypoglycaemia. All patients received therapy with ¹⁷⁷Lu-DOTA-TATE after conventional therapies failed in controlling disease progression and symptoms. The activity administered per cycle was 4.8-7.4 GBq. The interval between cycles was 10-16 weeks. Haematology, liver and kidney function tests were performed before treatment initiation and 5 and 10 weeks after each cycle.

RESULTS

Patient 1 presented significant clinical benefit for 13 months after PRRNT, with imaging improvement. Patient 2 obtained reduction of the number and severity of hypoglycaemic episodes during 15 months after therapy. Patient 3 is asymptomatic since PRRNT first cycle performed 23 months ago and revealed significant imaging improvement. Patient 4 had resolution of hypoglycaemia only 3 days after PRRNT first cycle and today, 16 months after therapy, the disease seems to be in remission and the patient maintains euglycaemic state. PRRNT was well tolerated, with only hematologic grade 2 toxicity in patient 1 and mild kidney toxicity in patient 3.

CONCLUSIONS

After the start of ¹⁷⁷Lu-DOTA-TATE all patients achieved hypoglycaemia symptomatic control and had evident improvement of their quality of life. Three patients showed imagiological improvement suggesting reduced tumour load.

Pancreatic neuroendocrine tumors: contemporary diagnosis and management

Pancreatic neuroendocrine tumors (PNETs) are neoplasms that arise from the hormone producing cells of the islets of Langerhans, also known as pancreatic islet cells. PNETs are considered a subgroup of neuroendocrine tumors, and have unique biology, natural history and clinical management. These tumors are classified as 'functional' or 'non-functional' depending on whether they release peptide hormones that produce specific hormone- related symptoms, usually in established patterns based on tumor subtype. This manuscript will review pancreatic neuroendocrine tumor subtypes, syndromes, diagnosis, and clinical management.

Somatostatin analog inhibits the growth of insulinoma cells by p27-mediated G1 cell cycle arrest

OBJECTIVES

Although the somatostatin analog octreotide (OCT) has been used for uncontrollable insulinoma, the mechanism involved is still unknown. The aim of this study was to elucidate the therapeutic effect of OCT for insulinoma.

METHODS

Mouse insulinoma cell line MIN6 cells were cultured with OCT to clarify its antiproliferative effects, the expression of somatostatin receptor subtypes, cell cycle, p27 expression, and cdc2 kinase activity. The changes of the messenger RNA expression profiles were examined by microarray analysis. Intraperitoneal OCT treatment was given to insulinoma model IT6 mice for 4 weeks.

RESULTS

MIN6 cells expressed somatostatin receptor 2A, 3, and 5 under the OCT treatment. Octreotide showed a dose-dependent antiproliferative effect on MIN6 cells but not on the other cell lines. p27 expression and cdc2 kinase activity in MIN6 cells became prominent with OCT treatment. At the messenger RNA level, several molecules in the mitogen-activated protein kinase signaling pathway were downregulated. The sizes of the individual tumors tended to be smaller in the OCT-treated group. p27 expression was seen in the tumor tissue, but no apoptotic marker was detected.

CONCLUSION

Octreotide acted through a cytostatic mechanism and could be an effective therapy for insulinoma.

Successful treatment of insulinoma by a single daily dose of octreotide in two elderly female patients

We report two cases of insulinoma in advanced age patients considered unsuitable for surgery, in whom single daily doses of octreotide successfully improved hypoglycemia and hyperinsulinemia. The biological half-life of octreotide is about 100 min, hence it is customary to use two or three administrations per day to prevent hypoglycemia in insulinoma patients. The first case was a 76-year-old woman who presented with hyperinsulinemic hypoglycemia. Computed tomography (CT) and magnetic resonance imaging did not identify a tumor in the pancreas but a 1.5-cm tumor was found in the pancreatic body on abdominal angiography and selective arterial calcium stimulation and hepatic venous sampling (ASVS) were compatible with insulinoma. The patient refused surgery, but was successfully treated with octreotide at 50 microg subcutaneous injection once daily. Since the treatment was started (1 year), she has not suffered hypoglycemia. Case 2 was an 85-year-old woman who presented with hyperinsulinemic hypoglycemia. CT identified a 1.5-cm tumor in the pancreatic uncus, but she was considered unsuitable for surgery due to advanced age, obesity and cardiopulmonary dysfunction. Octreotide at 100 microg subcutaneous injection once daily prevented further hypoglycemic attacks, but two months later, postprandial plasma glucose was elevated. Octreotide was gradually reduced to 50 microg once daily. Three years have passed since the treatment without any hypoglycemic attack. Successful treatment with octreotide once daily could be due to old-age-related slow metabolism and could be potentially considered as the treatment of choice for elderly patients with insulinoma especially those considered unsuitable for surgery.

Effect of octreotide on plasma concentrations of glucose, insulin, glucagon, growth hormone, and cortisol in healthy dogs and dogs with insulinoma

The inhibitory effect of the somatostatin analogue octreotide on the secretion of insulin could be used in the treatment of insulinoma. However, current information on the effectiveness of octreotide in dogs is conflicting. Therefore, the endocrine effects of a single subcutaneous dose of 50 microg octreotide were studied in healthy dogs in the fasting state (n=7) and in dogs with insulinoma (n=12). Octreotide did not cause any adverse effects. In healthy dogs in the fasting state, both plasma insulin and glucagon concentrations declined significantly. Basal (non-pulse related) GH and ACTH concentrations were not affected. A slight but significant decrease in the plasma glucose concentrations occurred. Dogs with insulinoma had significantly higher baseline insulin concentrations and lower baseline glucose concentrations than healthy dogs in the fasting state. Plasma glucagon, GH, ACTH, and cortisol concentrations did not differ from those in healthy dogs. Baseline plasma insulin concentrations decreased significantly in dogs with insulinoma after octreotide administration, whereas plasma concentrations of glucagon, GH, ACTH, and cortisol did not change. In contrast to the effects in the healthy dogs, in the dogs with insulinoma plasma glucose concentrations increased. Thus, the consistent suppression of plasma insulin concentrations in dogs with insulinoma, in the absence of an suppressive effect on counter-regulatory hormones, suggests that further studies on the effectiveness of slow-release preparations in the long-term medical treatment of dogs with insulinoma are warranted.

New developments in antidotes

Although some antidotes are rarely used, they have an important, potentially life-saving role in the treatment of toxic exposures. The timely and judicious use of an antidote can prevent death and shorten hospitalization as well as reduce the patient's pain and suffering. Although their importance is recognized, sufficient stocking of antidotes remains a problem.

A case of hyperinsulinemia of undetermined origin, successfully treated with long-acting octreotide

Major causes of fasting hypoglycemia in adults are insulinoma, factitious hypoglycemia and nesidioblastosis. The primary treatment for insulinoma is surgical removal of the tumor, but there are cases with hyperinsulinemia that cannot undergo surgery. Somatostatin analogue is one of the treatments used in such cases of insulinoma or persistent hyperinsulinemic hypoglycemia. We report here a patient who had undetermined hyperinsulinemia and was successfully treated with a long-acting somatostatin analogue, which had recently become available. The patient, a 72-year-old female, who had previously been diagnosed as insulinoma and undergone partial pancreatectomy, was admitted complaining of the recurrence of hypoglycemic attacks after an interval of ten years. On admission, hypoglycemia (42 mg/dl), hyperinsulinemia (IRI: 79.3 microU/m) and low HbA1c (3.6%) were present. In 75 g-OGTT at 30 min after load, IRI reached 6623 microU/ml, while plasma glucose level was 88 mg/dl. The anti-insulin antibody was not present. Since attempts at tumor localization by imaging techniques failed and the patient refused further examinations or surgical treatment, we recommended her to take a medication with a somatostatin analogue. Insulin suppression test using 50 microg of octreotide improved plasma glucose and IRI levels, suggesting the usefulness of the treatment, and a monthly administration of 20 mg of long-acting octreotide has successfully controlled her symptoms of hypoglycemia for 10 months. Our case demonstrated the utility of the long-acting somatostatin analogue for long-term treatment of undetermined hyperinsulinemia. A preliminary loading test using short-acting octreotide may be useful to determine appropriate medication, especially in cases who cannot receive surgical treatment.

Bench-to-bedside review: Antidotal treatment of sulfonylurea-induced hypoglycaemia with octreotide

The major potential adverse effect of use of sulfonylurea agents (SUAs) is a hyperinsulinaemic state that causes hypoglycaemia. It may be observed during chronic therapeutic dosing, even with very low doses of a SUA, and especially in older patients. It may also result from accidental or intentional poisoning in both diabetic and nondiabetic patients. The traditional approach to SUA-induced hypoglycaemia includes administration of glucose, and glucagon or diazoxide in those who remain hypoglycaemic despite repeated or continuous glucose supplementation. However, these antidotal approaches are associated with several shortcomings, including further exacerbation of insulin release by glucose and glucagon, leading only to a temporary beneficial effect and later relapse into hypoglycaemia, as well as the adverse effects of both glucagon and diazoxide. Octreotide inhibits the secretion of several neuropeptides, including insulin, and has successfully been used to control life-threatening hypoglycaemia caused by insulinoma or persistent hyperinsulinaemic hypoglycaemia of infancy. Therefore, this agent should in theory also be useful to decrease glucose requirements and the number of hypoglycaemic episodes in patients with SUA-induced hypoglycaemia. This has apparently been confirmed by experimental data, one retrospective study based on chart review, and several anecdotal case reports. There is thus a need for further prospective studies, which should be adequately powered, randomized and controlled, to confirm the probable beneficial effect of octreotide in this setting.

Use of octreotide to treat prolonged sulfonylurea-induced hypoglycemia in a patient with chronic renal failure

A diabetic patient with chronic renal failure who developed recurrent and prolonged episodes of hypoglycemia associated with use of sulfonylurea agent is presented here. This patient was hospitalized with neuroglycopenic symptoms of hypoglycemia that persisted in spite of large doses of parenteral glucose replacement. On administration of somatostatin analogue octreotide, hypoglycemia resolved and, blood glucose levels were maintained even after cessation of parenteral glucose. The patient received 2 subcutaneous doses of octreotide 12 hours apart, and made a complete recovery. Our experience suggests that use of octerotide to treat refractory or prolonged sulfonylurea-included hypoglycemia in renal failure patients is safe and effective; large prospective studies would be needed to validate these findings.

Somatostatin receptor imaging, therapy and new strategies in patients with neuroendocrine tumours

BACKGROUND

Somatostatin receptors have been found on a variety of neuroendocrine tumours, such as carcinoids and paragangliomas, as well as on most pancreatic endocrine and breast tumours. Somatostatin receptor scintigraphy with a radionuclide-labelled somatostatin analogue, [111Indium- diethylenetriaminopenta-acetic acid]octreotide, is a sensitive and specific technique for visualizing in vivo the presence of somatostatin receptors on various tumours.

METHODS

Material was identified from previous review articles, references cited in original papers and a Medline search of the literature. Additional material was obtained from recently published abstracts of meetings.

RESULTS AND CONCLUSION

Somatostatin receptor imaging of neuroendocrine tumours is essential in the diagnostic evaluation of most of these tumours. The expression of somatostatin receptors in vivo not only predicts the outcome of somatostatin analogue treatment but also opens the possibility of new therapeutic strategies. Because better information about spread of the disease can be obtained, more justifiable options for therapy can be proposed.

Octreotide: an antidote for sulfonylurea-induced hypoglycemia

STUDY OBJECTIVES

Sulfonylurea agents are widely used as therapy for hyperglycemia in type 2 diabetes mellitus. In overdose, these agents can produce sustained and profound hypoglycemia that is refractory to treatment with dextrose alone. Our objective was to determine whether treatment with octreotide decreases glucose requirements and the number of hypoglycemic episodes in patients with sulfonylurea-induced hypoglycemia.

METHODS

We retrospectively reviewed the charts of patients treated with octreotide for sulfonylurea-induced hypoglycemia from 1995 through 1998. The study took place in a large urban teaching hospital in the United States. We measured the number of episodes of hypoglycemia reported and the amount of dextrose used before and after treatment with octreotide. Using a failure time analysis, we compared the risk of hypoglycemia before and after octreotide administration.

RESULTS

The age range of the 9 patients was 20 to 65 years. Six patients ingested glyburide and 3 ingested glipizide. The number of hypoglycemic events recorded per patient before octreotide (mean 3.2) was greater than the number of hypoglycemic events recorded per patient after octreotide (mean 0.2, P =.008). Similarly, the number of ampules of 50% dextrose administered per patient before octreotide (mean 2.9) was greater than the number of ampules administered per patient after octreotide (0.2, P =.004). The risk of recurrent hypoglycemia before octreotide treatment was 27 times the risk of the group after octreotide treatment (P <.001). Stabilization of blood glucose concentration and cessation of rebound hypoglycemia occurred immediately after the administration of octreotide in all 9 patients.

CONCLUSION

Octreotide appears to be safe and effective in preventing rebound hypoglycemia after sulfonylurea ingestion. Octreotide in combination with dextrose should be considered for first-line therapy in the treatment of sulfonylurea-induced hypoglycemia.