Factitious hypoglycemia. Diagnosis by measurement of serum C-peptide immunoreactivity and insulin-binding antibodies

A retrospective study of 29 fatal cases of insulin overdose

PURPOSE

To summarize recent cases of fatal insulin poisoning both domestically and internationally, thereby offering valuable insights for the forensic identification of insulin overdose cases.

METHODS

Literature published since 2000 on fatal insulin overdose were systematically searched and screened. Data encompassing variables such as year, age, sex, cause of death, scene conditions, occupations, medical histories of victims and perpetrators, autopsy timing, dosage and administration methods, forensic pathology, and toxicological analysis, were compiled for rigorous statistical analysis.

RESULTS

Among the 29 fatal cases of insulin poisoning, suicides and homicides accounted for 55.2 % and 41.4 %, respectively. Precisely 34.5 % of victims or perpetrators were associated with the medical industry, 27.6 % had diabetes, and 24.1 % had mental illnesses such as depression. Intravenous injection resulted in quicker death than did subcutaneous injection. In some cases, immunohistochemical staining of insulin and protamine at injection sites yielded positive results. The average molar ratio of insulin to C-peptide in post-mortem blood was 13.76 ± 5.167, indicating a significant diagnostic value for insulin poisoning.

CONCLUSION

Assessment of cases of fatal insulin overdose should be thorough, incorporating case investigation, scene examination, medical records review, autopsy findings, pathological examinations, and laboratory tests, alongside considering the condition of the body and timing of death autopsy. Using mass spectrometry to detect insulin proves valuable, particularly in cases of poor body preservation.

Munchausen syndrome by proxy: a case report

BACKGROUND

Inappropriately high levels of insulin secretion can cause the potentially fatal condition of persistent hyperinsulinemic hypoglycemia of infancy. Our paper focuses on another cause of severe hypoglycemia, which can be easily missed.

CASE PRESENTATION

An 18-month-old Saudi female was referred to our hospital for further investigation and management of her recurrent hypoglycemic attacks as a case of persistent hyperinsulinemic hypoglycemia of infancy. During admission, we noticed multiple red flags from the history; the mother was insisting on a pancreatectomy, rather than going for a positron emission tomography scan, and most importantly, all hypoglycemic attacks occurred while the mother was around. Consequently, after further investigation, the case was diagnosed as a caregiver-fabricated illness, and the case was referred to the Child Protection Center.

CONCLUSIONS

One must have a high index of suspicion to diagnose caregiver-fabricated illness. Physicians should be more attentive to prevent such a disease, which could eventually become lethal if left unnoticed.

Characteristics of fatal insulin overdoses

This study was undertaken to review fatal cases of insulin overdose in South Australia (SA) over a 20-year period to assess rates and characteristics of insulin-related deaths among insulin-dependent diabetics and non-diabetics for all manners of death. Records from the National Coronial Information System (NCIS) and Forensic Science SA (FSSA) were searched for all cases of fatal insulin overdose in South Australia (SA) between 2000 and 2019. Collected variables included age, sex, cause of death, scene findings, manner of death, decedent medical and personal histories, biochemistry, toxicology, histopathology, and autopsy findings. Statistical analyses were performed using R (version 4.1.2). Forty cases of insulin overdose were identified in SA between 2000 and 2019. Twenty-nine cases (72.5%) were suicides, with the remaining cases classified as accidental or undetermined intent. Thirteen of the 22 insulin-dependent diabetics (59%) had a history of depression, 10 of whom had previously demonstrated suicidal ideation. The current study has shown that suicides using insulin among insulin-dependent diabetics are equally as prevalent, if not more so than fatal accidental insulin overdoses. This can largely be attributed to insulin-dependent diabetic access to a potentially lethal substance. Suicide prevention strategies should focus on insulin-dependent diabetics with a history of depression, particularly for those with access to rapid-acting insulin.

Increased C-Peptide Immunoreactivity in Insulin Autoimmune Syndrome (Hirata Disease) Due to High Molecular Weight Proinsulin

Background

Determination of C-peptide is important in the investigation of unexplained hyperinsulinemic hypoglycemia because a high C-peptide concentration usually indicates endogenous insulin hypersecretion. Insulin autoimmune syndrome (IAS) denotes hyperinsulinemic hypoglycemia due to insulin-binding antibodies that prolong insulin half-life. C-peptide clearance is considered to be unaffected, and although a marked C-peptide immunoreactivity in hypoglycemic samples has been reported, it has been suspected to be artifactual. High-resolution mass spectrometry enables examination of the basis of C-peptide-immunoreactivity in IAS.

Methods

Precipitation of plasma with polyethylene glycol was followed by C-peptide immunoassay. Plasma peptides extracted by solvent precipitation were characterized by nano-LC–MS/MS and analyzed using an untargeted data-dependent method. Peptides related to proinsulin, in amino acid sequence, were identified using proprietary bioinformatics software and confirmed by repeat LC–MS/MS analysis. Gel filtration chromatography coupled to LC–MS/MS was used to identify proinsulin-related peptides present in IAS immunocomplexes. Results were compared with those from C-peptide immunoassay.

Results

Polyethylene glycol precipitation of IAS plasma, but not control plasma, depleted C-peptide immunoreactivity consistent with immunoglobulin-bound C-peptide immunoreactivity. LC–MS/MS detected proinsulin and des 31,32 proinsulin at higher abundance in IAS plasma compared with control plasma. Analysis by gel filtration chromatography coupled to LC–MS/MS demonstrated proinsulin and des 31,32 proinsulin, but no C-peptide, in plasma immunocomplexes.

Conclusions

Antibody binding can enrich proinsulin and des 31,32 proinsulin in IAS immunocomplexes. Proinsulin cross-reactivity in some C-peptide immunoassays can lead to artifactually increased C-peptide results.

Factitious hypoglycemia in children and adolescents with diabetes

BACKGROUND

Factitious hypoglycemia is a condition of self-induced hypoglycemia due to surreptitious administration of insulin or oral hypoglycemic agents. In adults, it is an uncommon, but well known clinical entity observed in individuals with and without diabetes.

OBJECTIVES

To report a case of factitious hypoglycemia highlighting diagnostic pitfalls, to identify common characteristics of children and adolescents with factitious hypoglycemia, and to examine whether the information on long-term outcome exists.

METHODS

We present a case of an adolescent with type 1 diabetes who had self-induced hypoglycemia of several years' duration; and we conducted a systematic literature review on factitious hypoglycemia in pediatric patients with diabetes.

RESULTS

We identified a total of 83 articles of which 14 met the inclusion criteria (describing 39 cases). All but 1 individual had type 1 diabetes and the majority was female (63%). Average age was 13.5 ± 2.0 years with the youngest patient presenting at the age 9.5 years. Blood glucose control was poor (hemoglobin A1c: 12.1 ± 4.0%). In 35%, psychiatric disorders were mentioned as contributing factors. Only 3 reports provided follow-up beyond 6 months.

CONCLUSIONS

Factitious hypoglycemia typically occurs in adolescents with type 1 diabetes who use insulin to induce hypoglycemia. Awareness of this differential diagnosis and knowledge of potentially misleading laboratory results may facilitate earlier recognition and intervention. Little information exists on effective treatments and long-term outcome.

A Case of Acute Insulin Poisoning

A 32-year-old lady presented to the emergency department for suicidal attempt by self-injection of insulin (Protaphane 210 units). She developed repeated episodes of hypoglycaemia even with continuous intravenous infusion of 10% dextrose solution during observation. However, she did not develop serious complications of hypoglycaemia and was subsequently discharged after conservative treatment. Acute insulin poisoning is uncommon. The management of this uncommon poisoning is reviewed in this case report.

Treatment of sulfonylurea and insulin overdose

The most common toxicity associated with sulfonylureas and insulin is hypoglycaemia. The article reviews existing evidence to better guide hypoglycaemia management. Sulfonylureas and insulin have narrow therapeutic indices. Small doses can cause hypoglycaemia, which may be delayed and persistent. All children and adults with intentional overdoses need to be referred for medical assessment and treatment. Unintentional supratherapeutic ingestions can be initially managed at home but if symptomatic or if there is persistent hypoglycaemia require medical referral. Patients often require intensive care and prolonged observation periods. Blood glucose concentrations should be assessed frequently. Asymptomatic children with unintentional sulfonylurea ingestions should be observed for 12 h, except if this would lead to discharge at night when they should be kept until the morning. Prophylactic intravenous dextrose is not recommended. The goal of therapy is to restore and maintain euglycaemia for the duration of the drug's toxic effect. Enteral feeding is recommended in patients who are alert and able to tolerate oral intake. Once insulin or sulfonylurea-induced hypoglycaemia has developed, it should be initially treated with an intravenous dextrose bolus. Following this the mainstay of therapy for insulin-induced hypoglycaemia is intravenous dextrose infusion to maintain the blood glucose concentration between 5.5 and 11 mmol l(-1) . After sulfonylurea-induced hypoglycaemia is initially corrected with intravenous dextrose, the main treatment is octreotide which is administered to prevent insulin secretion and maintain euglycaemia. The observation period varies depending on drug, product formulation and dose. A general guideline is to observe for 12 h after discontinuation of intravenous dextrose and, if applicable, octreotide.

Commercial insulin immunoassays fail to detect commonly prescribed insulin analogues

OBJECTIVES

Blood insulin and C-peptide are key investigations in the differential diagnosis of hypoglycaemia. Analogues of insulin have modified primary-sequences compared to native human insulin, as such may not cross react with insulin assays. This has important implications in detecting surreptitious or malicious insulin administration. The aim of this study is to assess the cross-reactivity of all insulins currently listed in the British National Formulary (BNF65, 2013) in clinical insulin assays currently used in UK clinical laboratories.

DESIGN AND METHODS

Sample sets were prepared for all 15 exogenous insulin classes listed in the BNF, at concentrations of 1000 pmol/L and 300 pmol/L, using pooled human serum. Samples were sent blinded to 5 participating analytical laboratories to cover analysis on the 10 major clinical insulin assays used in the UK.

RESULTS

The ability of insulin assays to detect exogenous insulin preparations was highly variable and ranged from 0% to >140% for a single exogenous insulin. Four assays were highly specific for the human insulin sequence and had no cross-reactivity with any synthetic analogue insulin. Two detected all insulin types (human sequence, animal and synthetic analogue), with the remaining having variable cross-reactivity.

CONCLUSION

The cross-reactivity of the 15 exogenous insulin preparations is highly variable in the assays used in clinical laboratories around the UK. It is important that laboratories and clinicians are aware of the limitations of their local assays to avoid missing the important diagnosis of hypoglycaemia secondary to excessive exogenous insulin. Where necessary, samples should be referred to specialist centres for insulin analysis and ideally by a validated and fully-quantitative mass spectrometry-based method.

Adolescents with Type 1 diabetes mellitus experience psychosensorial symptoms during hypoglycaemia

AIM

To describe mood and psychosensorial symptoms of hypoglycaemia in adolescents with Type 1 diabetes mellitus in two countries with different cultures, Turkey and the USA.

METHODS

We developed a 68-item questionnaire assessing physical, behavioural, mood and psychosensorial symptom frequency and ratings ['good', 'bad', or 'both' (sometimes good, sometimes bad)]. Adolescents with Type 1 diabetes were recruited from paediatric diabetes clinics at the University of North Carolina at Chapel Hill in the USA and Kocaeli University in Turkey. The percentages of participants at each clinic who endorsed individual symptoms, symptom categories and symptom ratings were calculated and compared.

RESULTS

Cronbach's α values were > 0.7 for each real symptom category. No symptom items were excluded from the questionnaire analysis based on item-total correlation results which were all > 0.2. Data were collected from 132 participants (69 from University of North Carolina, 63 from Kocaeli University, 54% male). The mean (SD) age of the participants was 14.9 (1.9) years, HbA1c level was 8.7 (1.8) % and duration of Type 1 diabetes was 5.8 (3.7) years. On average, each physical symptom was experienced by 65.2% of participants, each behavioural symptom by 46.5%, each mood symptom by 42.8%, and each psychosensorial symptom by 48.9%. On average, each physical, behavioral, mood and psychosensorial symptom was rated as 'good' or 'both' by 23.0, 29.1, 36.9 and 37.2% of participants, respectively. There were no symptom differences between the groups in each country.

CONCLUSIONS

In addition to the classic physical symptoms experienced during hypoglycaemia, adolescents with Type 1 diabetes report psychosensorial, mood and behavioral symptoms, and some describe them as positive experiences. Symptom experiences were similar in these two countries with different cultures.

Forensic aspects of insulin

Insulin or, more appropriately, hypoglycaemia gives rise to a wide variety of interactions with the law. In most cases its role is not seriously open to question occasionally however, it is. This is especially true of situations in which insulin is suspected of having been used inappropriately or maliciously. The major differences between investigation of hypoglycaemia in clinical and forensic situation are that in the latter the history is often unreliable, appropriate samples for analysis were not collected, preserved or labelled correctly and analytical results are likely to be challenged on grounds of specificity, accuracy and interpretation. Immunoassay remains the mainstay of clinical investigation of hypoglycaemia but likely to become displaced by mass-spectrometry in the forensic situation especially now that human insulin is being replaced by synthetic insulin analogues for the treatment of diabetes.

Characteristics and Prevalence of Latent Autoimmune Diabetes in Adults (LADA)

Diabetes, one of the most commonly seen metabolic disorders, is affecting a major area of population in many developing as well as most of the developed countries and is becoming an alarming concern for the rising cost of the healthcare system. Latent Autoimmune Diabetes in Adults (LADA) is a form of diabetes which is less recognized and underdiagnosed type of diabetes which appears to have characteristics of both type 1 (autoimmune in nature) and type 2 diabetes (adult age at onset and initial response to oral hypoglycemic agents). An epidemiological study was carried out on 500 patients in the western region of India. Various parameters such as age at onset, duration of diabetes, gender, basal metabolic index (BMI), type of diabetes, family history, HbA1c levels, cholesterol levels, and current treatment regimen were evaluated and correlated with type 1 and type 2 diabetes. Moreover, diagnostic markers for LADA, namely, GAD autoantibodies and C-peptide levels, were determined for 80 patients selected from the epidemiological study. Some of the results obtained were found to be consistent with the literature whereas some results were found to be contradictory to the existing data.

Murder by insulin: suspected, purported and proven-a review

Murder by insulin-whether attempted, suspected or proven-is rare. Only 66 cases worldwide could be found for this review. A conviction was secured in 31 cases and additional weapon was employed in 11. Differentiation of attempted homicide from Munchausen syndrome by proxy in the young and from 'mercy killing' in the elderly was not attempted. Most perpetrators were close relatives and most victims were alive when discovered and responded to treatment. Hypoglycaemia is the first clue to homicidal insulin use in living subjects and requires the demonstration of a plasma insulin concentration of generally more than 1000 pmol/L and undetectable plasma C-peptide concentration to establish the diagnosis. Serum glucose measurements are valueless in victims found dead. The presence near the body of insulin vials, syringes or needles, loose talk by the suspected perpetrator or their ready access to insulin may be the only clue. The demonstration of insulin in tissue around an injection site by immunohistopathology or by measuring it in an extract clinches the diagnosis. Immunoassays suitable for clinical use to detect and measure insulin and C-peptide are subject to random errors and cannot be relied upon unless special precautions including separation by gel filtration or HPLC are undertaken prior to analysis. They do not detect or measure accurately a new generation of synthetic insulin analogues. Mass spectrometry will be required to do this and to validate clinical immunoassays, upon which convictions have always had to rely in the past.

Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline

OBJECTIVE

The aim is to provide guidelines for the evaluation and management of adults with hypoglycemic disorders, including those with diabetes mellitus.

EVIDENCE

Using the recommendations of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, the quality of evidence is graded very low (plus sign in circle ooo), low (plus sign in circle plus sign in circle oo), moderate (plus sign in circle plus sign in circle plus sign in circle o), or high (plus sign in circle plus sign in circle plus sign in circle plus sign in circle).

CONCLUSIONS

We recommend evaluation and management of hypoglycemia only in patients in whom Whipple's triad--symptoms, signs, or both consistent with hypoglycemia, a low plasma glucose concentration, and resolution of those symptoms or signs after the plasma glucose concentration is raised--is documented. In patients with hypoglycemia without diabetes mellitus, we recommend the following strategy. First, pursue clinical clues to potential hypoglycemic etiologies--drugs, critical illnesses, hormone deficiencies, nonislet cell tumors. In the absence of these causes, the differential diagnosis narrows to accidental, surreptitious, or even malicious hypoglycemia or endogenous hyperinsulinism. In patients suspected of having endogenous hyperinsulinism, measure plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and circulating oral hypoglycemic agents during an episode of hypoglycemia and measure insulin antibodies. Insulin or insulin secretagogue treatment of diabetes mellitus is the most common cause of hypoglycemia. We recommend the practice of hypoglycemia risk factor reduction--addressing the issue of hypoglycemia, applying the principles of intensive glycemic therapy, and considering both the conventional risk factors and those indicative of compromised defenses against falling plasma glucose concentrations--in persons with diabetes.

AAS, growth hormone, and insulin abuse: psychological and neuroendocrine effects

The nontherapeutic use of prescription medicines by individuals involved in sport is increasing. Anabolic-androgenic steroids (AAS) are the most widely abused drug. Much of our knowledge of the psychological and physiological effects of human growth hormone (hGH) and insulin has been learned from deficiency states. As a consequence of the Internet revolution, previously unobtainable and expensive designer drugs, particularly recombinant human growth hormone (rhGH) and insulin, have become freely available at ridiculously discounted prices from countries such as China and are being abused. These drugs have various physiological and psychological effects and medical personnel must become aware that such prescription medicine abuse appears to be used not only for performance and cosmetic reasons, but as a consequence of psychological pre-morbidity.

Pancreatic neuroendocrine tumours

Pancreatic neuroendocrine tumours (PET) are rare neoplasms of the pancreas accounting for less than 5% of all primary pancreatic malignancies. Included in this group are insulinomas, gastrinomas, glucagonoma and somatostatinomas. Collectively these neoplasms are classified as functional PETs. Where a PET is not associated with a clinical syndrome due to hormone oversecretion, it is referred to as a non-functioning PET. Non-functioning PETs are pancreatic tumours with endocrine differentiation but lack a clinical syndrome of hormone hypersecretion. The incidence of these tumours varied between 15 and 53%. Presentation is related to the mass effect of the tumour with symptoms often non-specific. Treatment is surgical excision with chemotherapy and hormonal therapy is controversial. For functioning PETs, surgery remains the optimal therapy, however, long-term survival can be expected even in the presence of metastases. With advances in medical management, radiolabelled somatostatin therapy, hepatic arterial chemoembolisation and radiofrequency ablation, symptoms may be controlled to optimize quality of life.

Surgery on neuroendocrine tumours

Neuroendocrine tumours of the gastrointestinal tract and pancreas present a major challenge to physicians in their recognition and treatment requirements, and surgical treatment of these tumours has become increasingly important for symptom palliation and survival. For some carcinoid tumours the extent of surgery may depend on tumour size. Midgut carcinoid is the most common cause of the carcinoid syndrome, requiring surgery for primary and mesenteric tumours to minimize the risk for abdominal complications but also for removal of liver metastases to palliate hormonal symptoms. Among endocrine pancreatic tumours, insulinoma and gastrinoma often cause severe symptoms of hormone excess despite their inconspicuous size, but they can be successfully removed with improved pre- and intraoperative localization. Other tumours--glucagonoma, VIPoma, and non-functioning endocrine pancreatic tumours--are often large or metastasizing, but generally require surgical debulking to alleviate hormonal symptoms and have favourable survival.

A case of secretin-responsive insulinoma with low serum C-peptide levels

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.

The management of insulinoma

BACKGROUND

Insulinomas are rare tumours. Their clinical presentation, localization techniques and operative management were reviewed.

METHODS

An electronic search of the Medline, Embase and Cochrane databases was undertaken for articles published between January 1966 and June 2005 on the history, presentation, clinical evaluation, use of imaging techniques for tumour localization and operative management of insulinoma.

RESULTS AND CONCLUSION

Most insulinomas are intrapancreatic, benign and solitary. Biochemical diagnosis is obtained during a supervised 72-h fast. Non-invasive preoperative imaging techniques to localize lesions continue to evolve. Intraoperative ultrasonography can be combined with other preoperative imaging modalities to improve tumour detection. Surgical resection is the treatment of choice. In the absence of preoperative localization and intraoperative detection of an insulinoma, blind pancreatic resection is not recommended.

Current concepts in functioning endocrine tumors of the pancreas

Duodenal and pancreatic endocrine tumors are uncommon and their surgical treatment is often difficult. The management of these tumors has changed with recent advancements in tumor localization, intraoperative hormone measurements, standardized surgical techniques, and a better understanding of the genetic basis of multiple endocrine neoplasia syndrome. We present our experience with 191 endocrine tumors and elaborate the contemporary management of functioning duodenopancreatic endocrine tumors.

Surgical treatment of endocrine pancreatic tumours

Endocrine pancreatic tumours (EPTs) are uncommon, with a major challenge to alert physicians to their recognition and requirements of treatment. Functioning EPTs cause well-known clinical syndromes of hormone excess. Insulinomas, gastrinomas and glucagonomas are most common; vipomas and somatostatinomas are rare. EPTs also occur as non-functioning lesions without symptoms of hormone excess occasionally with ectopic hormone, such as ACTH and Cushing syndrome as a late complication. The majority of EPTs are sporadic, but they may also be part of a multiple endocrine neoplasia type 1 syndrome or rarely the von Hippel-Lindau syndrome. EPTs have been of great interest to endocrine surgeons and we have, during recent years, witnessed continuing advances in diagnosis, imaging and treatment of the different tumour entities. It has become obvious that surgical treatment of these tumours is of increased concern and can have a marked impact on symptoms and survival.

Factitious hypoglycemia: a tale from the Arab world

The mother is usually the one who narrates the patient's history to the pediatrician. Listening and eliciting the parent's story is an art. One of the essential attributes of a good pediatrician is the readiness to believe the parent's story. Mothers are good historians and careful observers. The axiom that the mother is always right is true in most instances. However, occasionally the clinician is deliberately misled by the storyteller, resulting in numerous and potentially dangerous diagnostic investigations. We describe a boy with recurrent hypoglycemic coma in whom the diagnosis of factitious hypoglycemia was delayed as it is believed to be nonexistent in our community. We emphasize that in all patients with recurrent hypoglycemia, estimation of C-peptide and insulin should be performed even when the clinical settings are not in favor of the diagnosis of Munchausen syndrome by proxy. Munchausen syndrome by proxy, hypoglycemia.

Hypoglycemia: factitious and felonious

Factitious diseases are characterized by physical or psychologic symptoms that are voluntarily self-induced. These diseases are as old as mankind. Once called "malingerers," these patients must be distinguished from hysterics in whom symptoms are produced unconsciously. In factitious diseases, illness is produced by deliberate acts by the patient who when seeking medical help omits to mention them and may continue strenuously to deny them even when confronted with the evidence. Factitious diseases occur in patients who simulate or exaggerate symptoms or disability to obtain some kind of discernible personal gain or avoid an unpleasant situation; however, such actions may only produce disadvantages by exposing the patient to the risk of death or permanent injury. This has been described as Munchausen syndrome, which is probably a manifestation of severe psychiatric disease. The use of medicines or poisons to induce illness in others also produces a type of factitial disease and presents similar or greater difficulties in diagnosis. In both situations, the clinical history, ordinarily the most important clue to the correct diagnosis, is not only incomplete but often misleading. Sometimes referred to as Munchausen by proxy, this form of factitial disease may be impossible to distinguish from attempted murder or grievous bodily harm. The subtle differences between these disorders, if any, have not been discussed herein.

Clinical features of 52 neonates with hyperinsulinism

BACKGROUND

Neonatal hyperinsulinemic hypoglycemia is often resistant to medical therapy and is often treated with near-total pancreatectomy. However, the pancreatic lesions may be focal and treatable by partial pancreatic resection.

METHODS

We studied 52 neonates with hyperinsulinism who were treated surgically. The type and location of the pancreatic lesions were determined by preoperative pancreatic catheterization and intraoperative histologic studies. Partial pancreatectomy was performed in infants with focal lesions, and near-total pancreatectomy was performed in those with diffuse lesions. The postoperative outcome was determined by measurements of plasma glucose and glycosylated hemoglobin and by oral glucose-tolerance tests.

RESULTS

Thirty neonates had diffuse beta-cell hyperfunction, and 22 had focal adenomatous islet-cell hyperplasia. Among the latter, the lesions were in the head of the pancreas in nine, the isthmus in three, the body in eight, and the tail in two. The clinical manifestations were similar in both groups. The infants with focal lesions had no symptoms of hypoglycemia and had normal preprandial and postprandial plasma glucose and glycosylated hemoglobin values and normal results on oral glucose-tolerance tests after partial pancreatectomy (performed in 19 of 22 neonates). By contrast, after near-total pancreatectomy, 13 of the patients with diffuse lesions had persistent hypoglycemia, type 1 diabetes mellitus developed in 8, and hyperglycemia developed in another 7; overall, only 2 patients with diffuse lesions had normal plasma glucose concentrations in the first year after surgery.

CONCLUSIONS

Among neonates with hyperinsulinism, about half may have focal islet-cell hyperplasia that can be treated with partial pancreatectomy. These neonates can be identified through pancreatic catheterization and intraoperative histologic studies.

Subtle psychiatric presentations of endocrine diseases

Endocrine disorders frequently present initially to psychiatrists. This article reviews the differential diagnosis of psychiatric and endocrine disorders. The range of endocrinopathies is presented, with emphasis placed on the common psychiatric symptomatology associated with these conditions. Various signs and symptoms that might stimulate a psychiatrist to pursue a work-up for each endocrine disorder are also emphasized.

Hypoglycemia factitia: Munchhausen syndrome in diabetes mellitus

The medical history of a 43-year-old non-insulin-dependent diabetic patient with severe and repetitive hypoglycemic episodes is reported. The exact diagnosis proved to be difficult. Finally, surreptitious insulin administration was documented by high serum insulin and low C-peptide values with an elevated molar ratio of insulin to C-peptide in peripheral venous blood during hypoglycemia. Confronting the patient with evidences of surreptitious insulin administration, hypoglycemic episodes abruptly stopped. Hypoglycemia factitia was assessed as a manifestation of Munchhausen syndrome in diabetes mellitus.

Basal and glucagon-stimulated plasma C-peptide concentrations in healthy dogs, dogs with diabetes mellitus, and dogs with hyperadrenocorticism

Serum glucose and plasma C-peptide response to i.v. glucagon administration was evaluated in 24 healthy dogs, 12 dogs with untreated diabetes mellitus, 30 dogs with insulin-treated diabetes mellitus, and 8 dogs with naturally acquired hyperadrenocorticism. Serum insulin response also was evaluated in all dogs, except 20 insulin-treated diabetic dogs. Blood samples for serum glucose, serum insulin, and plasma C-peptide determinations were collected immediately before and 5, 10, 20, 30, and (for healthy dogs) 60 minutes after i.v. administration of 1 mg glucagon per dog. In healthy dogs, the patterns of glucagon-stimulated changes in plasma C-peptide and serum insulin concentrations were identical, with single peaks in plasma C-peptide and serum insulin concentrations observed approximately 15 minutes after i.v. glucagon administration. Mean plasma C-peptide and serum insulin concentrations in untreated diabetic dogs, and mean plasma C-peptide concentration in insulin-treated diabetic dogs did not increase significantly after i.v. glucagon administration. The validity of serum insulin concentration results was questionable in 10 insulin-treated diabetic dogs, possibly because of anti-insulin antibody interference with the insulin radioimmunoassay. Plasma C-peptide and serum insulin concentrations were significantly increased (P < .001) at all blood sampling times after glucagon administration in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Five-minute C-peptide increment, C-peptide peak response, total C-peptide secretion, and, for untreated diabetic dogs, insulin peak response and total insulin secretion were significantly lower (P < .00l) in diabetic dogs, compared with healthy dogs, whereas these same parameters were significantly increased (P < .01) in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Although not statistically significant, there was a trend for higher plasma C-peptide concentrations in untreated diabetic dogs compared with insulin-treated diabetic dogs during the glucagon stimulation test. Baseline C-peptide concentrations also were significantly higher (P < .05) in diabetic dogs treated with insulin for less than 6 months, compared with diabetic dogs treated for longer than 1 year. Finally, 7 of 42 diabetic dogs had baseline plasma C-peptide concentrations greater than 2 SD (ie, > 0.29 pmol/mL) above the normal mean plasma C-peptide concentration; values that were significantly higher, compared with the results in healthy dogs (P < .001) and with the other 35 diabetic dogs (P < .001). In summary, measurement of plasma C-peptide concentration during glucagon stimulation testing allowed differentiation among healthy dogs, dogs with impaired beta-cell function (ie, diabetes mellitus), and dogs with increased beta-cell responsiveness to glucagon (ie, insulin resistance). Plasma C-peptide concentrations during glucagon stimulation testing were variable in diabetic dogs and may represent dogs with type-1 and type-2 diabetes or, more likely, differences in severity of beta-cell loss in dogs with type-1 diabetes.

Factitious Cushing’s Syndrome: Discovery with Use of a Sensitive Immunoradiometric Assay for Corticotropin

Factitious Cushing's syndrome is an unusual problem that may be clinically and biochemically indistinguishable from endogenous hypercortisolism. Results of biochemical studies may be misleading because of cross-reactivity of synthetic corticosteroids or their metabolites with plasma or urine cortisol. Because of its lack of specificity, radioimmunoassay (RIA) for corticotropin (adrenocorticotropic hormone or ACTH) may not show completely suppressed results in patients with surreptitious use of glucocorticoids. A new sensitive and specific immunoradiometric assay (IRMA) for ACTH demonstrates reliably suppressed levels after administration of glucocorticoids. In this report, we describe a 37-year-old woman with typical clinical and biochemical features of ACTH-dependent hypercortisolism. Metabolic evaluation had shown urinary free cortisol excretion of 7,499 nmol/day and plasma ACTH-RIA levels of 13.2 and 33.0 pmol/L on two separate occasions. The use of IRMA for the measurement of ACTH during inferior petrosal sinus sampling revealed a very low peripheral ACTH concentration (=0.4 pmol/L) and a considerably blunted response to ovine corticotropin-releasing hormone, findings that suggested ACTH-independent Cushing's syndrome. Plasma samples obtained during inferior petrosal sinus sampling were assayed for prednisolone and showed a concentration of 360 nmol/L; thus, the presence of factitious Cushing's syndrome was confirmed. Some commercial ACTH-RIA measurements may be unreliable in distinguishing ACTH-dependent from ACTH-independent hypercortisolism. ACTH-IRMA levels are low in patients with ACTH-independent Cushing's syndrome and will be helpful in identifying factitious Cushing's syndrome.

Intentional massive insulin overdose: recognition and management

A case of intentional massive insulin overdose requiring prolonged glycemic support is presented. Suicidal insulin overdose may be more common than generally appreciated. Because hypoglycemic reactions are evaluated routinely in the ED, emergency physicians should maintain a high degree of suspicion regarding suicidal intent or foul play in diabetics with hypoglycemia who respond minimally to the administration of concentrated glucose solutions or in hypoglycemic presentations by nondiabetics who have access to diabetic medications. Fingerstick glucose evaluations or serum glucose levels should be obtained routinely at 15 to 30 minutes after glucose administration in any hypoglycemic patient to gauge the intensity of glucose use. Inability to maintain euglycemia following glucose administration suggests excessive insulin and requires further workup. Evaluation of serum insulin and C-peptide levels is useful in confirming intentional overdoses in cases that are not clear-cut. Glucose infusion rates must be tailored individually to each overdose situation as great individual variability exists in insulin absorption and effects. The clinician should anticipate the possible need for prolonged glycemic support in this setting.

Case report: factitious hypoglycemia in diabetic patients

Factitious hypoglycemia (FH) in a diabetic patient represents a difficult diagnostic and costly management problem. An adolescent diabetic with FH is reported. A literature search revealed 10 adolescent and 45 adult diabetic patients with FH. Tests currently available for diagnosis are evaluated. The role of psychiatric therapy in relation to overall management and prognosis is stressed.

When to worry about hypoglycemia

The important causes of hypoglycemia unrelated to known diabetes are relatively few. Postprandial hypoglycemia is a relatively benign disorder. Fasting hypoglycemia is more serious and may be caused by metabolic disturbances or tumors. Several hereditary disorders cause hypoglycemia in infants and must be diagnosed and treated before serious damage occurs. A systematic clinical approach increases the likelihood of making the correct diagnosis in a timely fashion.

Insulin misuse: a review of an overlooked psychiatric problem

A number of forms of insulin misuse, other than the usual noncompliance, have been reported in the literature on the treatment of diabetes mellitus. These include attempted and completed suicide, factitious hypoglycemia, Munchausen syndrome by proxy, and the use of insulin by substance abusers. Such misuse has involved diabetic patients, their family members and medical staff, as well as others. The reports of suicide attempts reveal an equal distribution of misuse between the sexes (rather than the expected preponderance of females), underrepresentation of adolescents, and a high rate of recurrence. Recommendations for treatment are discussed for clinicians and investigators regarding this overlooked problem.

Insulin abuse in long-standing IDDM

Two patients with insulin-dependent diabetes mellitus (IDDM) for 42 and 46 years respectively were diagnosed to produce factitious hypoglycemia. They had several properties in common: abnormal personality, refusal to stop incipient hypoglycemia, ideal body weight, good hemoglobin A1c (HbA1c) values, non-specific changes in the EEG, and brain atrophy sparing the periventricular areas. The addiction forced the patients to continue their habit during hospital stay. The dose of surreptitiously injected regular insulin always produced serum insulin concentrations large enough to clarify the diagnosis.

Autoimmune insulin syndrome

Initially described in Japan, the autoimmune insulin syndrome is caused by the presence of anti-insulin antibodies in patients who have never received insulin. This syndrome accounts for spontaneous or reactive hypoglycaemia with very high levels of total immuno-reactive insulin. Discordance between the levels of immunoreactive insulin and C peptide indicate the possible presence of anti-insulin antibodies; this can avoid an incorrect diagnosis of insulinoma. These autoimmune hypoglycaemias often present a difficult diagnostic problem in distinguishing them from factitious hypoglycaemia. The course of the autoimmune insulin syndrome is usually favourable, with a spontaneous rapid diminution of the levels of anti-insulin antibodies. The reasons for the appearance of anti-insulin antibodies and the exact mechanisms of the hypoglycaemia remain uncertain. However, the frequent association of the autoimmune insulin syndrome with certain autoimmune diseases suggest a common immune dysfunction. Drugs containing a sulphydryl group have been implicated in the aetiology of this syndrome.

Factitious hyperinsulinemic hypoglycemia: confirmation of the diagnosis by a species-specific insulin radioimmunoassay

Surreptitious self-administration of insulin is an important cause of hypoglycemia. A 28-year-old female hospital ward clerk presented with hypoglycemia associated with an elevated plasma insulin level and a low plasma C-peptide concentration. Factitious illness was denied by the patient until it was definitively proven by using a species-specific insulin radioimmunoassay that the type of insulin circulating at the time of hypoglycemia was of animal rather than of human origin. The differential diagnosis of hypoglycemia associated with hyperinsulinemia and the current laboratory methods which may be employed to distinguish between factitious hypoglycemia and endogenous hyperinsulinism are discussed.

[Factitious disease. Observations on 44 cases at a medical clinic and recommendation for a subclassification]

From 1971 to 1985, 44 cases of self-induced factitious disorders were observed in the Medical Department of a University Hospital. The diseases were often severe, one patient even died. The various symptoms and diseases presented by the patients, the methods of producing them, and the diagnostic and therapeutic aspects of these cases are described. Patients were analysed with regard to age, sex, profession, psychosocial adaptation, number and duration of hospitalisations, presentation of complaints, behaviour on the ward, relation to the doctor, self-destructive tendencies, readiness to suffer and possible motivations. According to the criteria of the DSM-III, seven patients were malingerers (DSM-III: V 65.20) and 37 had a "chronic factitious disorder with physical symptoms" (DSM-III: 301.51). However, the findings in the patients of the latter group strongly suggest that they form an extremely heterogeneous population. Therefore we propose a subclassification of the DSM-III category 301.51 as follows: Type A. Muenchausen syndrome in the proper sense; dramatic deception of mainly acute illness; pseudologia fantastica; social maladaptation, chaotic life situations; many, mostly short hospitalisations; many interventions; at first well adapted, later hostile; mostly men. Type B. Self-induced, mainly chronic illness; behaviour adequate, highly compliant; often little emotion, contrasting with the sometimes severe illness; socially adapted; history remarkably blank with regard to psychosocial stress; several often longlasting hospitalisations and many interventions; almost exclusively younger women from (para-)-medical professions. Type C. Willfull interference with the healing of wounds, cutaneous ulcers, abscesses or dermatological artefacts; history with marked personal losses or severe chronic medical problems; at first well adapted, later hostile, passive/aggressive; women prevail. A conversion syndrome (DSM-III: 300.11) was not observed. In contrast to malingering, the basis of the disorder in types A, B and C is unconscious in origin, thus similar to the conversion syndrome. Contrary to the latter, however, the production of physical symptoms is under voluntary control. The proposed subclassification represents a hypothesis for testing which might facilitate the analysis of the basic personality disorder, so far lacking. The investigation of the psychopathology of these patients and their treatment is difficult if not impossible because most refuse psychiatric exploration and therapy. Consequently follow-up studies and data on the prognosis are rare.

Use of biosynthetic human C-peptide in the measurement of insulin secretion rates in normal volunteers and type I diabetic patients

We undertook this study to examine the accuracy of plasma C-peptide as a marker of insulin secretion. The peripheral kinetics of biosynthetic human C-peptide (BHCP) were studied in 10 normal volunteers and 7 insulin-dependent diabetic patients. Each subject received intravenous bolus injections of BHCP as well as constant and variable rate infusions. After intravenous bolus injections the metabolic clearance rate of BHCP (3.8 +/- 0.1 ml/kg per min, mean +/- SEM) was not significantly different from the value obtained during its constant intravenous infusion (3.9 +/- 0.1 ml/kg per min). The metabolic clearance rate of C-peptide measured during steady state intravenous infusions was constant over a wide concentration range. During experiments in which BHCP was infused at a variable rate, the peripheral concentration of C-peptide did not change in proportion to the infusion rate. Thus, the infusion rate of BHCP could not be calculated accurately as the product of the C-peptide concentration and metabolic clearance rate. However, the non-steady infusion rate of BHCP could be accurately calculated from peripheral C-peptide concentrations using a two-compartment mathematical model when model parameters were derived from the C-peptide decay curve in each subject. Application of this model to predict constant infusions of C-peptide from peripheral C-peptide concentrations resulted in model generated estimates of the C-peptide infusion rate that were 101.5 +/- 3.4% and 100.4 +/- 2.8% of low and high dose rates, respectively. Estimates of the total quantity of C-peptide infused at a variable rate over 240 min based on the two-compartment model represented 104.6 +/- 2.4% of the amount actually infused. Application of this approach to clinical studies will allow the secretion rate of insulin to be estimated with considerable accuracy. The insulin secretion rate in normal subjects after an overnight fast was 89.1 pmol/min, which corresponds with a basal 24-h secretion of 18.6 U.