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Open access

Daphne Yau, Maria Salomon-Estebanez, Amish Chinoy, John Grainger, Ross J Craigie, Raja Padidela, Mars Skae, Mark J Dunne, Philip G Murray and Indraneel Banerjee

Summary

Congenital hyperinsulinism (CHI) is an important cause of severe hypoglycaemia in infancy. To correct hypoglycaemia, high concentrations of dextrose are often required through a central venous catheter (CVC) with consequent risk of thrombosis. We describe a series of six cases of CHI due to varying aetiologies from our centre requiring CVC for the management of hypoglycaemia, who developed thrombosis in association with CVC. We subsequently analysed the incidence and risk factors for CVC-associated thrombosis, as well as the outcomes of enoxaparin prophylaxis. The six cases occurred over a 3-year period; we identified an additional 27 patients with CHI who required CVC insertion during this period (n = 33 total), and a separate cohort of patients with CHI and CVC who received enoxaparin prophylaxis (n = 7). The incidence of CVC-associated thrombosis was 18% (6/33) over the 3 years, a rate of 4.2 thromboses/1000 CVC days. There was no difference in the frequency of genetic mutations or focal CHI in those that developed thromboses. However, compound heterozygous/homozygous potassium ATP channel mutations correlated with thrombosis (R 2 = 0.40, P = 0.001). No difference was observed in CVC duration, high concentration dextrose or glucagon infused through the CVC. In patients receiving enoxaparin prophylaxis, none developed thrombosis or bleeding complications. The characteristics of these patients did not differ significantly from those with thrombosis not on prophylaxis. We therefore conclude that CVC-associated thrombosis can occur in a significant proportion (18%) of patients with CHI, particularly in severe CHI, for which anticoagulant prophylaxis may be indicated.

Learning points:

  • CVC insertion is one of the most significant risk factors for thrombosis in the paediatric population.

  • Risk factors for CVC-associated thrombosis include increased duration of CVC placement, malpositioning and infusion of blood products.

  • To our knowledge, this is the first study to evaluate CVC-associated thrombosis in patients with congenital hyperinsulinism (CHI).

  • The incidence of CVC-associated thrombosis development is significant (18%) in CHI patients and higher compared to other neonates with CVC. CHI severity may be a risk factor for thrombosis development.

  • Although effective prophylaxis for CVC-associated thrombosis in infancy is yet to be established, our preliminary experience suggests the safety and efficacy of enoxoaparin prophylaxis in this population and requires on-going evaluation.

Open access

Ved Bhushan Arya, Jennifer Kalitsi, Ann Hickey, Sarah E Flanagan and Ritika R Kapoor

Summary

Diazoxide is the first-line treatment for patients with hyperinsulinaemic hypoglycaemia (HH). Approximately 50% of patients with HH are diazoxide resistant. However, marked diazoxide sensitivity resulting in severe hyperglycaemia is extremely uncommon and not reported previously in the context of HH due to HNF4A mutation. We report a novel observation of exceptional diazoxide sensitivity in a patient with HH due to HNF4A mutation. A female infant presented with severe persistent neonatal hypoglycaemia and was diagnosed with HH. Standard doses of diazoxide (5 mg/kg/day) resulted in marked hyperglycaemia (maximum blood glucose 21.6 mmol/L) necessitating discontinuation of diazoxide. Lower dose of diazoxide (1.5 mg/kg/day) successfully controlled HH in the proband, which was subsequently confirmed to be due to a novel HNF4A mutation. At 3 years of age, the patient maintains age appropriate fasting tolerance on low dose diazoxide (1.8 mg/kg/day) and has normal development. Diagnosis in proband’s mother and maternal aunt, both of whom carried HNF4A mutation and had been diagnosed with presumed type 1 and type 2 diabetes mellitus, respectively, was revised to maturity-onset diabetes of young (MODY). Proband’s 5-year-old maternal cousin, also carrier of HNF4A mutation, had transient neonatal hypoglycaemia. To conclude, patients with HH due to HNF4A mutation may require lower diazoxide than other group of patients with HH. Educating the families about the risk of marked hyperglycaemia with diazoxide is essential. The clinical phenotype of HNF4A mutation can be extremely variable.

Learning points:

  • Awareness of risk of severe hyperglycaemia with diazoxide is important and patients/families should be accordingly educated.

  • Some patients with HH due to HNF4A mutations may require lower than standard doses of diazoxide.

  • The clinical phenotype of HNF4A mutation can be extremely variable.

Open access

Seong Keat Cheah, David Halsall, Peter Barker, John Grant, Abraham Mathews, Shyam Seshadri and Singhan Krishnan

Summary

A frail 79-year-old lady with dementia presented with a 2-year history of frequent falls. Recurrent hypoglycaemic episodes were diagnosed and treated with continuous glucose infusion in multiple hospital admissions. Hypoadrenalism and hypothyroidism were ruled out. Whilst hypoglycaemic (blood glucose 1.6 mmol/L), both plasma C-peptide and proinsulin concentrations, were inappropriately elevated at 4210 pmol/L (174–960) and >200 pmol/L (0–7) respectively with plasma insulin suppressed at 12 pmol/L (0–180). Whilst reported cases of proinsulinoma are typically pancreatic in origin, radiological investigations of the pancreas in this patient did not identify abnormalities. Unexpectedly contrast CT identified a heterogeneously enhancing mass (6.6 cm) at the lower pole of the left kidney consistent with renal cell carcinoma. Non-islet cell tumour-induced hypoglycaemia has been associated with renal malignancy; however, a serum IGF2:IGF1 ratio measured at <10 effectively excludes this diagnosis. Concomitantly on the CT, extensive peripherally enhancing heterogeneous mass lesions in the liver were identified, the largest measuring 12 cm. A palliative approach was taken due to multiple comorbidities. On post-mortem, the kidney lesion was confirmed as clear cell renal carcinoma, whilst the liver lesions were identified as proinsulin-secreting neuroendocrine tumours. In conclusion, the diagnosis of proinsulinoma can be missed if plasma proinsulin concentration is not measured at the time of hypoglycaemia. In this case, the plasma insulin:C-peptide ratio was too high to be accounted for by the faster relative clearance of insulin and was due to proinsulin cross-reactivity in the C-peptide assay. In addition, the concomitant malignancy proved to be a challenging red herring.

Learning points:

  • Even in non-diabetics, hypoglycaemia needs to be excluded in a setting of frequent falls. Insulin- or proinsulin-secreting tumours are potentially curable causes.

  • Whilst investigating spontaneous hypoglycaemia, if plasma insulin concentration is appropriate for the hypoglycaemia, it is prudent to check proinsulin concentrations during the hypoglycaemic episode.

  • Proinsulin cross-reacts variably with C-peptide and insulin assays; the effect is method dependent. In this case, the discrepancy between the insulin and C-peptide concentrations was too great to be accounted for by the faster relative clearance of insulin, raising the suspicion of assay interference. The C-peptide assay in question (Diasorin liaison) has been shown to be 100% cross reactive with proinsulin based on spiking studies with a proinsulin reference preparation.

  • Whilst reported cases of proinsulinoma and 99% of insulinomas are of pancreatic origin, conventional imaging studies (CT, MRI or ultrasound) fail to detect neuroendocrine tumours <1 cm in 50% of cases.

  • The concomitant renal mass identified radiologically proved to be a red herring.

  • In view of the rarity of proinsulinoma, no conclusive association with renal cell carcinoma can be established.

Open access

Peter Novodvorsky, Emma Walkinshaw, Waliur Rahman, Valerie Gordon, Karen Towse, Sarah Mitchell, Dinesh Selvarajah, Priya Madhuvrata and Alia Munir

Summary

Bariatric surgery is an effective therapy for obesity but is associated with long-term complications such as dumping syndromes and nutritional deficiencies. We report a case of a 26-year-old caucasian female, with history of morbid obesity and gestational diabetes (GDM), who became pregnant 4 months after Roux-en-Y bypass surgery. She developed GDM during subsequent pregnancy, which was initially managed with metformin and insulin. Nocturnal hypoglycaemia causing sleep disturbance and daytime somnolence occured at 19 weeks of pregnancy (19/40). Treatment with rapid-acting carbohydrates precipitated further hypoglycaemia. Laboratory investigations confirmed hypoglycaemia at 2.2 mmol/L with appropriately low insulin and C-peptide, intact HPA axis and negative IgG insulin antibodies. The patient was seen regularly by the bariatric dietetic team but concerns about compliance persisted. A FreeStyle Libre system was used from 21/40 enabling the patient a real-time feedback of changes in interstitial glucose following high or low GI index food intake. The patient declined a trial of acarbose but consented to an intraveneous dextrose infusion overnight resulting in improvement but not complete abolishment of nocturnal hypoglycaemia. Hypoglycaemias subsided at 34/40 and metformin and insulin had to be re-introduced due to high post-prandial blood glucose readings. An emergency C-section was indicated at 35 + 1/40 and a small-for-gestational-age female was delivered. There have been no further episodes of hypoglycaemia following delivery. This case illustrates challenges in the management of pregnancy following bariatric surgery. To our knowledge, this is the first use of FreeStyle Libre in dumping syndrome in pregnancy following bariatric surgery with troublesome nocturnal hypoglycaemia.

Learning points:

  • Bariatric surgery represents the most effective treatment modality in cases of severe obesity. With increasing prevalence of obesity, more people are likely to undergo bariatric procedures, many of which are women of childbearing age.

  • Fertility generally improves after bariatric surgery due to weight reduction, but pregnancy is not recommended for at least 12–24 months after surgery. If pregnancy occurs, there are currently little evidence-based guidelines available on how to manage complications such as dumping syndromes or gestational diabetes (GDM) in women with history of bariatric surgery.

  • Diagnosis of GDM relies on the use of a 75 g oral glucose tolerance test (OGTT). The use of this test in pregnant women is not recommended due to its potential to precipitate dumping syndrome. Capillary glucose monitoring profiles or continuous glucose monitoring (CGM) is being currently discussed as alternative testing modalities.

  • As the CGM technology becomes more available, including the recently introduced FreeStyle Libre Flash glucose monitoring system, more pregnant women, including those after bariatric surgery, will have access to this technology. We suggest urgent development of guidelines regarding the use of CGM and flash glucose monitoring tools in these circumstances and in the interim recommend careful consideration of their use on a case-to-case basis.

Open access

Dinesh Giri, Prashant Patil, Rachel Hart, Mohammed Didi and Senthil Senniappan

Summary

Poland syndrome (PS) is a rare congenital condition, affecting 1 in 30 000 live births worldwide, characterised by a unilateral absence of the sternal head of the pectoralis major and ipsilateral symbrachydactyly occasionally associated with abnormalities of musculoskeletal structures. A baby girl, born at 40 weeks’ gestation with birth weight of 3.33 kg (−0.55 SDS) had typical phenotypical features of PS. She had recurrent hypoglycaemic episodes early in life requiring high concentration of glucose and glucagon infusion. The diagnosis of congenital hyperinsulinism (CHI) was biochemically confirmed by inappropriately high plasma concentrations of insulin and C-peptide and low plasma free fatty acids and β-hydroxyl butyrate concentrations during hypoglycaemia. Sequencing of ABCC8, KCNJ11 and HNF4A did not show any pathogenic mutation. Microarray analysis revealed a novel duplication in the short arm of chromosome 10 at 10p13–14 region. This is the first reported case of CHI in association with PS and 10p duplication. We hypothesise that the HK1 located on the chromosome 10 encoding hexokinase-1 is possibly linked to the pathophysiology of CHI.

Learning points:

  • Congenital hyperinsulinism (CHI) is known to be associated with various syndromes.

  • This is the first reported association of CHI and Poland syndrome (PS) with duplication in 10p13–14.

  • A potential underlying genetic link between 10p13–14 duplication, PS and CHI is a possibility.

Open access

Benjamin G Challis, Nicolai J Wewer Albrechtsen, Vishakha Bansiya, Keith Burling, Peter Barker, Bolette Hartmann, Fiona Gribble, Stephen O'Rahilly, Jens J Holst and Helen L Simpson

Summary

Pancreatic neuroendocrine tumours (pNETs) secreting proglucagon are associated with phenotypic heterogeneity. Here, we describe two patients with pNETs and varied clinical phenotypes due to differential processing and secretion of proglucagon-derived peptides (PGDPs). Case 1, a 57-year-old woman presented with necrolytic migratory erythema, anorexia, constipation and hyperinsulinaemic hypoglycaemia. She was found to have a grade 1 pNET, small bowel mucosal thickening and hyperglucagonaemia. Somatostatin analogue (SSA) therapy improved appetite, abolished hypoglycaemia and improved the rash. Case 2, a 48-year-old male presented with diabetes mellitus, diarrhoea, weight loss, nausea, vomiting and perineal rash due to a grade 1 metastatic pNET and hyperglucagonaemia. In both cases, plasma levels of all measured PGDPs were elevated and attenuated following SSA therapy. In case 1, there was increased production of intact glucagon-like peptide 1 (GLP-1) and GLP-2, similar to that of the enteroendocrine L cell. In case 2, pancreatic glucagon was elevated due to a pancreatic α-cell-like proglucagon processing profile. In summary, we describe two patients with pNETs and heterogeneous clinical phenotypes due to differential processing and secretion of PGDPs. This is the first description of a patient with symptomatic hyperinsulinaemic hypoglycaemia and marked gastrointestinal dysfunction due to, in part, a proglucagon-expressing pNET.

Learning points

  • PGDPs exhibit a diverse range of biological activities including critical roles in glucose and amino acid metabolism, energy homeostasis and gastrointestinal physiology.

  • The clinical manifestations of proglucagon-expressing tumours may exhibit marked phenotypic variation due to the biochemical heterogeneity of their secreted peptide repertoire.

  • Specific and precise biochemical assessment of individuals with proglucagon-expressing tumours may provide opportunities for improved diagnosis and clinical management.

Open access

G K Dimitriadis, K Gopalakrishnan, R Rao, D K Grammatopoulos, H S Randeva, M O Weickert and N Murthy

Summary

We report the case of a 70-year-old previously healthy female who presented acutely to the Accident and Emergency department with left-sided vasomotor symptoms including reduced muscle tone, weakness upon walking and slurred speech. Physical examination confirmed hemiparesis with VIIth nerve palsy and profound hepatomegaly. A random glucose was low at 1.7 mmol/l, which upon correction resolved her symptoms. In hindsight, the patient recalled having had similar episodes periodically over the past 3 months to which she did not give much attention. While hospitalized, she continued having episodes of symptomatic hypoglycaemia during most nights, requiring treatment with i.v. dextrose and/or glucagon. Blood tests including insulin and C-peptide were invariably suppressed, in correlation with low glucose. A Synacthen stimulation test was normal (Cort (0′) 390 nmol/l, Cort (30′) 773 nmol/l). A computed tomography scan showed multiple lobulated masses in the abdomen, liver and pelvis. An ultrasound guided biopsy of one of the pelvic masses was performed. Immunohistochemistry supported the diagnosis of a gastrointestinal stromal tumour (GIST) positive for CD34 and CD117. A diagnosis of a non islet cell tumour hypoglycaemia (NICTH) secondary to an IGF2 secreting GIST was confirmed with further biochemical investigations (IGF2=96.5 nmol/l; IGF2:IGF1 ratio 18.9, ULN <10). Treatment with growth hormone resolved the patient's hypoglycaemic symptoms and subsequent targeted therapy with Imatinib was successful in controlling disease progression over an 8-year observation period.

Learning points

  • NICTH can be a rare complication of GISTs that may manifest with severe hypoglycaemia and neuroglucopenic symptoms.

  • NICTH can masquerade as other pathologies thus causing diagnostic confusion.

  • Histological confirmation of GIST induced NICTH and exclusion of other conditions causing hypoglycaemia is essential.

  • Mutational analysis of GISTs should be carried out in all cases as it guides treatment decision.

  • Tailored management of hypoglycaemia, in this case using growth hormone and targeted cyto-reductive therapy, minimizes the risk of possible life-threatening complications.

Open access

M Nwokolo and J Fletcher

Summary

A 46-year-old woman presented multiple times in a 4-month period with hypotension, sepsis, hypoglycaemia and psychosis. A low random cortisol in combination with her presenting complaint made adrenal insufficiency the likely diagnosis. Fluid resuscitation and i.v. steroid therapy led to clinical improvement; however, a short synacthen test (SST) demonstrated an apparently satisfactory cortisol response. The test was repeated on a later admission and revealed a peak cortisol level of 25 nmol/l (>550 nmol/l). Concurrent treatment with i.v. hydrocortisone had led to a false-negative SST. ACTH was <5 ng/l (>10 ng/l), indicating secondary adrenal failure. We discuss the challenges surrounding the diagnosis of adrenal insufficiency and hypopituitarism, the rare complication of psychosis and a presumptive diagnosis of autoimmune lymphocytic hypophysitis (ALH).

Learning points

  • Adrenocortical insufficiency must be considered in the shocked, hypovolaemic and hypoglycaemic patient with electrolyte imbalance. Rapid treatment with fluid resuscitation and i.v. corticosteroids is vital.

  • Polymorphic presentations to multiple specialities are common. Generalised myalgia, abdominal pain and delirium are well recognised, psychosis is rare.

  • A random cortisol can be taken with baseline bloods. Once the patient is stable, meticulous dynamic testing must follow to confirm the clinical diagnosis.

  • The chronic disease progression of ALH is hypothesised to be expansion then atrophy of the pituitary gland resulting in empty sella turcica and hypopituitarism.

  • If hypopituitarism is suspected, an ACTH deficiency should be treated prior to commencing thyroxine (T4) therapy as unopposed T4 may worsen features of cortisol deficiency.