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Open access

Noman Ahmad, Abdulmonem Mohammed Almutawa, Mohamed Ziyad Abubacker, Hossam Ahmed Elzeftawy and Osama Abdullah Bawazir

Summary

An insulinoma is a rare tumour with an incidence of four cases per million per year in adults. The incidence in children is not established. There is limited literature available in children with insulinoma, and only one case is reported in association with Down’s syndrome in adults. Insulinoma diagnosis is frequently missed in adults as well as in children. The Whipple triad is the most striking feature although it has limited application in young children. Hypoglycaemia with elevated insulin, C-peptide and absent ketones is highly suggestive of hyperinsulinism. We present a case of 10-year-old boy with Down’s syndrome with recurrent insulinoma. He was initially misdiagnosed as having an adrenal insufficiency and developed cushingoid features and obesity secondary to hydrocortisone treatment and excessive sugar intake. The tumour was successfully localised in the head of the pancreas with an MRI and octreotide scan on first presentation. Medical treatment with diazoxide and octreotide could not achieve normal blood glucose levels. The insulinoma was laparoscopically enucleated and pathological examination confirmed a neuroendocrine tumour. Subsequently, he had complete resolution of symptoms. He had a recurrence after 2 years with frequent episodes of hypoglycaemia. The biochemical workup was suggestive of hyperinsulinism. MRI and PET scan confirmed the recurrence at the same site (head of the pancreas). He had an open laparotomy for insulinoma resection. The pathology was consistent with benign insulinoma, and subsequently, he had complete resolution of symptoms.

Learning points:

  • Insulinoma is a very rare tumour in children; it should be considered in the differential diagnosis of hypoglycaemia with absent ketones.

  • Refractory neurological symptoms like seizure, migraine, mood changes and regression of learning abilities should suggest evaluation for hypoglycaemia.

  • MRI with contrast and PET scan would localise the majority of pancreatic beta islet cell lesions.

  • Medical treatment with diazoxide, octreotide and the addition of corn starch in feeds is not curative but can be supportive to maintain normoglycemia until the surgical resection.

  • Surgical resection is the only curative treatment. The surgical procedure of choice (laparoscopic/open laparotomy) depends on local expertise, preoperative localisation, tumour size and number.

  • Surgical treatment results in complete resolution of symptoms, but all cases should be closely followed up to monitor for recurrence. The recurrence rate is four times higher in MEN1 cases.

Open access

Adriana de Sousa Lages, Isabel Paiva, Patrícia Oliveira, Francisco Portela and Francisco Carrilho

Summary

Insulinomas are the most frequent cause of hyperinsulinaemic hypoglycaemia. Although surgical enucleation is the standard treatment, a few other options are available to high-risk patients who are elderly or present with co-morbidities. We present a case report of an 89-year-old female patient who was admitted to the emergency department due to recurrent hypoglycaemia, especially during fasting. Laboratory work-up raised the suspicion of hyperinsulinaemic hypoglycaemia, and abdominal CT scan revealed a 12 mm nodular hypervascular lesion of the pancreatic body suggestive of neuroendocrine tumour. The patient was not considered a suitable candidate for surgery, and medical therapy with diazoxide was poorly tolerated. Endoscopic ultrasound-guided ethanol ablation therapy was performed and a total of 0.6 mL of 95% ethanol was injected into the lesion by a transgastric approach; no complications were reported after the procedure. At 5 months of follow-up, no episodes of hypoglycaemia were reported, no diazoxide therapy was necessary, and revaluation abdominal CT scan revealed a pancreatic nodular lesion with a size involution of about half of its original volume. The patient is regularly followed-up at the endocrinology clinic and shows a significant improvement in her wellbeing and quality of life.

Learning points:

  • Insulinomas are the most frequent cause of hyperinsulinaemic hypoglycaemia.

  • Surgical enucleation is the standard treatment with a few other options available to high-risk patients.

  • Endoscopic ultrasound-guided ethanol ablation therapy is one feasible option in high-risk patients with satisfactory clinical outcomes, significant positive impact on quality of life and low complication rates related to the procedure.

Open access

Chih-Ting Su and Yi-Chun Lin

Summary

Insulin antibodies (IA) associated with exogenous insulin administration seldom caused hypoglycemia and had different characteristics from insulin autoantibodies (IAA) found in insulin autoimmune syndrome (IAS), which was first described by Dr Hirata in 1970. The characteristic of IAS is the presence of insulin-binding autoantibodies and related fasting or late postprandial hypoglycemia. Here, we report a patient with type 1 diabetes mellitus under insulin glargine and insulin aspart treatment who developed recurrent spontaneous post-absorptive hyperinsulinemic hypoglycemia with the cause probably being insulin antibodies induced by exogenous injected insulin. Examinations of serial sera disclosed a high titre of insulin antibodies (33%, normal <5%), high insulin concentration (111.9 IU/mL) and undetectable C-peptide when hypoglycemia occurred. An oral glucose tolerance test revealed persistent high serum levels of total insulin and undetectable C-peptide. Image studies of the pancreas were unremarkable, which excluded the diagnosis of insulinoma. The patient does not take any of the medications containing sulfhydryl compounds, which had been reported to cause IAS. After administering oral prednisolone for 3 weeks, hypoglycemic episodes markedly improved, and he was discharged smoothly.

Learning points:

  • Insulin autoimmune syndrome (IAS) or IAS-like situation should be one of the differential diagnosis in patients with hyperinsulinemic hypoglycemia.

  • Although less reported, insulin antibodies (IA) caused by exogenous insulin analog should be considered as the cause of hypoglycemia.

  • Patients with suspected insulin autoimmune syndrome (IAS) should be screened for drugs related to autoimmunity to endogenous insulin.

Open access

Anthony Logaraj, Venessa H M Tsang, Shahrir Kabir and Julian C Y Ip

Summary

Adrenal haemorrhage is a rare cause of adrenal crisis, which requires rapid diagnosis, prompt initiation of parenteral hydrocortisone and haemodynamic monitoring to avoid hypotensive crises. We herein describe a case of bilateral adrenal haemorrhage after hemicolectomy in a 93-year-old female with high-grade colonic adenocarcinoma. This patient’s post-operative recovery was complicated by an acute hypotensive episode, hypoglycaemia and syncope, and subsequent computed tomography (CT) scan of the abdomen revealed bilateral adrenal haemorrhage. Given her labile blood pressure, intravenous hydrocortisone was commenced with rapid improvement of blood pressure, which had incompletely responded with fluids. A provisional diagnosis of hypocortisolism was made. Initial heparin-induced thrombocytopenic screen (HITTS) was positive, but platelet count and coagulation profile were both normal. The patient suffered a concurrent transient ischaemic attack with no neurological deficits. She was discharged on a reducing dose of oral steroids with normal serum cortisol levels at the time of discharge. She and her family were educated about lifelong steroids and the use of parenteral steroids should a hypoadrenal crisis eventuate.

Learning points:

  • Adrenal haemorrhage is a rare cause of hypoadrenalism, and thus requires prompt diagnosis and management to prevent death from primary adrenocortical insufficiency.

  • Mechanisms of adrenal haemorrhage include reduced adrenal vascular bed capillary resistance, adrenal vein thrombosis, catecholamine-related increased adrenal blood flow and adrenal vein spasm.

  • Standard diagnostic assessment is a non-contrast CT abdomen.

  • Intravenous hydrocortisone and intravenous substitution of fluids are the initial management.

  • A formal diagnosis of primary adrenal insufficiency should never delay treatment, but should be made afterwards.

Open access

Kah-Yin Loke, Andrew Sng Anjian, Yvonne Lim Yijuan, Cindy Ho Wei Li, Maria Güemes and Khalid Hussain

Summary

Hyperinsulinaemic hypoglycaemia (HH), which causes persistent neonatal hypoglycaemia, can result in neurological damage and it’s management is challenging. Diazoxide is the first-line treatment, albeit not all patients will fully respond to it, as episodes of hypoglycaemia may persist and it entails unpleasant adverse effects. Sirolimus, an mTOR inhibitor, has reportedly been successful in treating children with severe diffuse HH, thus obviating the need for pancreatectomy. We report a girl with HH, with a novel heterozygous ABCC8 gene missense mutation (c.4154A>T/ p.Lys1385Thr), who was initially responsive to diazoxide therapy. After 11 months of diazoxide treatment, she developed intermittent, unpredictable breakthrough episodes of hypoglycaemia, in addition to generalized hypertrichosis and weight gain from enforced feeding to avoid hypoglycaemia. Sirolimus, which was commenced at 15 months of age, gradually replaced diazoxide, with significant reduction and abolition of hypoglycaemia. The hypertrichosis resolved and there was less weight gain given the reduced need for enforced feeding. Sirolimus, which was administered over the next 15 months, was well tolerated with no significant side effects and was gradually weaned off. After stopping sirolimus, apart from hypoglycaemia developing during an episode of severe viral gastroenteritis, the capillary glucose concentrations were maintained >3.5 mmol/L, even after a 10 h fast. Sirolimus may have a role in the treatment of partially diazoxide-responsive forms of HH who experience breakthrough hypoglycaemia, but the long-term safety and efficacy of sirolimus are not established.

Learning points:

  • Conventional treatment of diffuse HH with diazoxide is not always effective in controlling hypoglycaemia and can be associated with unpleasant side effects.

  • Sirolimus was successfully used to abolish recurrent hypoglycaemia in partially diazoxide-responsive HH, with resolution of unacceptable diazoxide-associated side effects.

  • Sirolimus was well tolerated with no clinically significant side effects.

  • Shortly after stopping sirolimus, the capillary glucose levels remained normoglycemic.

Open access

Chun-Han Lo and Ding-Ping Sun

Summary

Insulinomas are the most common cause of hypoglycemia resulting from endogenous hyperinsulinism. Traditionally, inappropriately elevated levels of insulin in the face of hypoglycemia are the key to diagnosis. However, contradictory levels of insulin and C-peptide do not necessarily exclude the diagnosis. A 50-year-old female was brought to our emergency department because of conscious disturbance on the previous night. She had no history of diabetes mellitus, and was not using any medications or alcohol. Laboratory data showed low sugar, a significantly low insulin level, and elevated C-peptide. After admission, she had multiple episodes of spontaneous hypoglycemia after overnight fasts without discomfort. It was considered that a neuroendocrine tumor was the source of her hypoglycemia. CT scan of the abdomen revealed a 1.1cm hypervascular nodule in the pancreatic tail. Elective laparoscopic distal pancreatectomy was incorporated into her treatment course. A 1.2×1.0cm homogenous well-encapsulated tumor was resected. We monitored her glucose levels in the outpatient clinic every month for a period of six months. She did not have another episode of spontaneous hypoglycemia.

Learning points

  • Insulinoma causes endogenous hypoglycemia – it cannot be ruled out in patients presenting with hypoglycemia and low insulin levels; history and imaging studies should be done for further assessment

  • A 24-h fast test has the same clinical significance as that of 72-h fast test

  • C-peptide is a useful biochemical marker in addition to serum insulin, which can be used to diagnose insulinomas

  • CT scan is used to measure the tumor size and localize the tumor. However, definitive diagnosis is only achieved through histopathologic evaluation of diseased tissue

Open access

Nishant Raizada, S H Rahaman, D Kandasamy and V P Jyotsna

Summary

Insulin autoimmune syndrome (IAS) is a rare cause of hyperinsulinemic hypoglycaemia, which is known to occur in association with the use of sulfhydryl-containing drugs and autoimmune disorders. We describe a patient with hitherto an unreported association of IAS with ankylosing spondylitis. We have also performed and described a simplified method of polyethylene glycol (PEG) precipitation of an insulin bound antibody in the serum.

Learning points

  • IAS should be considered in differential diagnosis of endogenous hyperinsulinemic hypoglycaemia.

  • Ankylosing spondylitis can be associated with IAS apart from several other autoimmune diseases.

  • Very high serum insulin levels (100–10 000 μU/ml) are frequently seen in IAS.

  • When faced with very high serum insulin before suspecting insulinoma, it is advisable that PEG precipitation of serum be done to identify antibody bound insulin.

  • A clinical suspicion of IAS can avoid expensive imaging and unnecessary surgery in affected patients.

Open access

S Solomou, R Khan, D Propper, D Berney and M Druce

Summary

A 33-year-old male was diagnosed with a metastatic neuroendocrine carcinoma of uncertain primary. He defaulted from follow-up without therapy and some months later developed episodic severe hypoglycaemia, which was found to be associated with inappropriately elevated insulin and C-peptide levels. It was considered likely that the neuroendocrine tumour was the source of the insulin secretion. Diazoxide and somatostatin analogue were used to control hypoglycaemia. Much later in the course of the disease, he developed metabolic derangement, increased skin pigmentation and psychological disturbance, without frankly Cushingoid physical findings. Investigations revealed highly elevated cortisol levels (the levels having previously been normal) with markedly raised ACTH levels, consistent with the co-secretion of ACTH and insulin by the tumour. Treatment with metyrapone improved his psychological state and electrolyte imbalance. Unfortunately, despite several cycles of first-, second- and third-line chemotherapy from the start of the first hormonal presentation onwards, imaging revealed widespread progressive metastatic disease and the patient eventually passed away. This case highlights the importance of keeping in mind the biochemical heterogeneity of endocrine tumours during their treatment.

Learning points

  • The clinical presentation of insulin-secreting tumours includes symptoms of neuroglycopaenia and sympathetic overstimulation.

  • Tumour-associated hypoglycaemia can be due to pancreatic insulinomas, and although ectopic hormone production occurs in a number of tumours, ectopic secretion of insulin is rare.

  • A possible switch in the type of hormone produced can occur during the growth and progression of neuroendocrine tumours and, when treating neuroendocrine tumours, it is important to keep in mind their biochemical heterogeneity.

Open access

Suresh Chandran, Fabian Yap Kok Peng, Victor Samuel Rajadurai, Yap Te Lu, Kenneth T E Chang, S E Flanagan, S Ellard and Khalid Hussain

Summary

background: Congenital hyperinsulinism (CHI) is a rare genetic disorder characterised by inappropriate insulin secretion in the face of severe hypoglycaemia. There are two histological subtypes of CHI namely diffuse and focal. Diffuse CHI is most common due to recessive mutations in ABCC8/KCNJ11 (which encode the SUR/KIR6.2 components of the pancreatic β-cell KATP channel) whereas focal CHI is due to a paternally inherited ABCC8/KCNJ11 mutation and somatic loss of heterozygosity for the 11p allele inside the focal lesion. Fluorine-18-l-dihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA-PET/CT) is used in the pre-operative localisation of focal lesions prior to surgery. Diffuse CHI if medically unresponsive will require a near total pancreatectomy whereas focal CHI will only require a limited lesionectomy, thus curing the patient from the hypoglycaemia.

Aims: To report the first case of genetically confirmed CHI in Singapore from a heterozygous paternally inherited ABCC8 mutation.

Methods/Results: A term male infant presented with severe hyperinsulinaemic hypoglycaemia (HH) after birth and failed medical treatment with diazoxide and octreotide. Genetic testing (paternally inherited mutation in ABCC8/p.D1472N) suggested focal disease, but due to the unavailability of 18F-DOPA-PET/CT to confirm focal disease, a partial pancreatectomy was performed. Interestingly, histology of the resected pancreatic tissue showed changes typical of diffuse disease.

Conclusion: Heterozygous paternally inherited ABCC8/KCNJ11 mutations can lead to diffuse or focal CHI.

Learning points

  • HH is a cause of severe hypoglycaemia in the newborn period.

  • Paternal mutations in ABCC8/KCNJ11 can lead to diffuse or focal disease.

  • 18F-DOPA-PET/CT scan is the current imaging of choice for localising focal lesions.

  • Gallium-68 tetra-aza-cyclododecane-N NNN-‴-tetra-acetate octreotate PET scan is not a useful imaging tool for localising focal lesions.

  • The molecular mechanism by which a heterozygous ABCC8 mutation leads to diffuse disease is currently unclear.

  • Focal lesions are curable by lesionectomy and so genetic studies in patients with HH must be followed by imaging using 18F-DOPA-PET/CT scan.