Hypoglycemia due to a monoclonal insulin-binding antibody in multiple myeloma

Resolution of dysglycaemia after treatment of monoclonal gammopathy of endocrine significance

In very rare cases of monoclonal gammopathy, insulin-binding paraprotein can cause disabling hypoglycaemia. We report a 67-year-old man re-evaluated for hyperinsulinaemic hypoglycaemia that persisted despite distal pancreatectomy. He had no medical history of diabetes mellitus or autoimmune disease but was being monitored for an IgG kappa monoclonal gammopathy of undetermined significance. On glucose tolerance testing, hyperglycaemia occurred at 60 min (glucose 216 mg/dL) and hypoglycaemia at 300 min (52 mg/dL) concurrent with an apparent plasma insulin concentration of 52 850 pmol/L on immunoassay. Laboratory investigation revealed an IgG2 kappa with very high binding capacity but low affinity (Kd 1.43 × 10-6 mol/L) for insulin. The monoclonal gammopathy was restaged as smouldering myeloma not warranting plasma cell-directed therapy from a haematological standpoint. Plasma exchange reduced paraprotein levels and improved fasting capillary glucose concentrations. Lenalidomide was used to treat disabling hypoglycaemia, successfully depleting paraprotein and leading to resolution of symptoms.

Duplication of AKT2 Gene in Ovarian Cancer: A Potentially Novel Mechanism for Tumor-Induced Hypoglycemia

Severe hypoglycemia occurs with different types of tumors, including islet cell and non-islet cell tumors. Non-islet cell tumor hypoglycemia (NICTH) is a rare and potentially life-threatening complication of malignancy. The primary underlying mechanism of NICTH proposed in the literature includes paraneoplastic overproduction of insulin-like growth factor-2 (IGF-2), the production of autoantibodies against insulin or its receptors, or the presence of extensive metastatic burden replacing hepatic tissue or adrenal glands. In this report, we propose a potentially novel mechanism underlying NICTH involving stimulation of the insulin signaling pathway in a 58-year-old woman with a rare ovarian tumor of Müllerian origin that carries a duplication of the AKT2 gene. AKT2 is a molecular mediator of insulin signaling. To our knowledge, this is the first reported case of tumor-induced hypoglycemia associated with AKT2 gene duplication. In this report also, we discuss the currently available diagnostic modalities and highlight the therapeutic rationale in patients with NICTH, a highly vulnerable population.

Comparison of patient characteristics between East Asian and non-East Asian patients with insulin autoimmune syndrome

OBJECTIVE

Insulin autoimmune syndrome (IAS) is the third most common cause of spontaneous hypoglycaemia in Japan but very rare in the rest of the world. We aimed to identify factors, which are associated with the occurrence of IAS and which may differ between East Asian and non-East Asian patients.

DESIGN

A PubMed search using the search terms 'insulin autoimmune syndrome' and 'Hirata disease' revealed a total of 287 reports of IAS cases, including one previously unpublished own case.

RESULTS

Mean age (±standard deviation) was 52 ± 19 years in East Asian and 54 ± 21 years in non-East Asian patients (p > .05). In both groups, there were more females. Mean body mass index was lower in East Asian than in non-East Asian patients (23.0 ± 4.3 vs. 27.1 ± 5.6 kg/m² , p < .0001). Postprandial hypoglycaemia was more common in non-East Asian patients (p < .05). East Asian patients took more frequently antithyroid medications and non-East Asian patients angiotensin-converting enzyme (ACE) inhibitors (both p < .0001). Graves' disease and other autoimmune diseases were more frequently observed in East Asian patients (both p < .01). Parameters of glucose metabolism were comparable in both groups, independent of diabetes diagnosis (p > .05), except for insulin that was higher in East Asian compared to non-East Asian metabolically healthy patients (p < .01). Human leukocyte antigen (HLA)-DRB1*0406 was the most frequent HLA-type in East Asian patients (p < .0001), whereas DRB1*0403 and *0404 were more frequent in non-East Asian patients (both p < .05). Non-East Asian patients received more secondary treatments, including plasmapheresis and rituximab, whereas medication discontinuation was more common in East Asian patients (all p < .05). Outcome was similar in both groups (p > .05).

CONCLUSIONS

Factors associated with IAS markedly differ between East Asian and non-East Asian patients, with autoimmune disorders, particularly Graves' disease, antithyroid medications, and HLA-DRB1*0406 more prevalent in East Asian patients and cardiovascular and plasma cell diseases, ACE inhibitors and HLA-DRB1*0403 more prevalent in non-East Asian patients.

[Hypoglycemic syndrome in patients with monoclonal gammopathy]

One of the reasons for the development of hypoglycemia is the synthesis of autoimmune antibodies to insulin or its receptor &ndash; insulin autoimmune syndrome (IAS). The largest number of cases of this syndrome is described in the Japanese population. The antibodies to insulin are most often polyclonal immunoglobulins. In monoclonal gammopathy of undetermined significance and multiple myeloma secreted pathological monoclonal immunoglobulin may have an affinity for human insulin, which induces the development of IAS. The prolonged persistence of episodes of hypoglycemia of unknown origin requires the exclusion of the monoclonal nature of secreted antibodies to insulin. Often the presence of pathological secretion for a long time is not recognized due to the absence of other manifestations of the disease. The manifestation of gammopathy is represented by a wide range of symptoms and syndromes requiring the collaboration of doctors of various specialties. This review summarizes the literature on IAS in patients with monoclonal gammopathy, whose disease debuted from episodes of spontaneous hypoglycemia. When hemoblastosis remission is achieved (when the secretion of the pathological protein is minimal or not determined), the glucose, insulin, and antibodies levels of insulin normalize, and when multiple myeloma recurs, episodes of hypoglycemia resume. The onset of the disease from the IAS can be considered as a new criterion for symptomatic multiple myeloma, dictating the need for the initiation of specific therapy.

Monoclonal antibody therapy in multiple myeloma

The therapeutic landscape of multiple myeloma (MM) has evolved spectacularly over the past decade with the discovery and validation of proteasome inhibitors and immunomodulatory agents as highly active agents, both in front-line therapy as well as in the relapse and maintenance settings. Although previous attempts to apply available monoclonal antibodies (Mabs) to the treatment of patients with MM has until recently been disappointing, novel targets specifically explored in the context of MM have recently lead to the first approvals of Mabs for the treatment of patients with MM. We have performed a literature search to identify preclinical targeting of MM, including in vitro and in vivo models using monoclonal antibodies, as well as clinical trials of monoclonal antibodies in patients with MM. Sources used were peer-reviewed publications, congress abstracts and on-line clinical trials data (such as clinicaltrials.gov). Several targets have been evaluated in preclinical models and a growing number of agents are being evaluated in clinical trials, as single agents or in combination and under various antibody formats. Two agents, targeting for the first time CD38 and SLAMF7, respectively, have recently been approved for the treatment of patients with MM. The recent approval of these two antibodies is expected to have a strong impact on treatment modalities and outcome in patients with MM, including both transplant eligible and elderly patients.

Antibody-Mediated Insulin Resistance: When Insulin and Insulin Receptor Act as Autoantigens in Humans

We report the case of a patient with diabetes presenting a severe insulin-resistance syndrome due to the production of insulin autoantibodies by a lymphocytic lymphoma. We describe the various mechanisms leading to the production of insulin autoantibodies and insulin receptor autoantibodies and review the therapeutic possibilities.

Insulin Autoimmune Syndrome Accompanied by Multiple Myeloma

In 1981, a 48-year old man was diagnosed with insulin autoimmune syndrome. In 2005, he experienced a substantial increase in his monoclonal insulin antibody levels; in 2006 and 2007, serum monoclonal gammopathy and an 11% marrow plasmacyte ratio were confirmed. In 2012, asymptomatic multiple myeloma was diagnosed based on an increased γ-globulin fraction and serum M-protein (IgG) levels. The insulin antibody binding rate was 75.4% in 2005 and 78.8% in 2012. In 2012, he was hospitalized for ileus and died. Autopsy identified multiple myeloma and no endocrinological tumors in the pancreas.

Hypoglycemia Secondary to Sulfonylurea Ingestion in a Patient with End Stage Renal Disease: Results from a 72-Hour Fast

Insulin, proinsulin, and C-peptide levels increase with sulfonylurea exposure but the acuity of increase has not been described in dialysis patients. We present a case of a dialysis patient who presented with hypoglycemia and was found to have accidental sulfonylurea ingestion. This is a 73-year-old man with ESRD on peritoneal dialysis, without history of diabetes, who presented with hypoglycemia. Past medical history includes multiple myeloma, congestive heart failure, and hypertension. At initial presentation, his blood glucose was 47 mg/dL, with concomitant elevations in the following: C-peptide 30.5 (nl: 0.8-3.5 ng/mL), insulin 76 (nl: 3-19 μIU/mL), and proinsulin 83.3 (nl: ≤8.0 pmol/L). During the 72-hour fast, which he completed without hypoglycemia, insulin declined to be within normal limits (to 12 μIU/mL); proinsulin (to 12.1 pmol/L) and C-peptide (to 7.2 ng/mL) levels decreased but remained elevated. The sulfonylurea screen ultimately returned positive for glipizide, clinching the diagnosis. This is the first reported case which characterizes the chronic elevation of proinsulin in a patient with ESRD, as well as its dramatic increase after a presumed solitary exposure to sulfonylurea. The 72-hour fast conducted gives insight into the clearance of insulin, proinsulin, and C-peptide after sulfonylurea ingestion in ESRD.

Unusual Manifestations of Essential Monoclonal Gammopathy. II. Simulation of the Insulin Autoimmune Syndrome

In rare cases, the monoclonal immunoglobulin that characterizes essential monoclonal gammopathy interacts with a self-antigen with functional consequences and a resulting clinical syndrome. This event is presumably random and results from the clone of B lymphocytes making a monoclonal immunoglobulin that simulates an autoimmune antibody. Thus, by chance, the monoclonal immunoglobulin has sufficient affinity for an epitope on a normal protein that functional consequences ensue. One such rare event is the synthesis and secretion of a monoclonal immunoglobulin that binds to human insulin. Inactivation of insulin by antibody results in (1) an early postprandial hyperglycemia, (2) followed by either or both (i) a reactive overshot in insulin secretion, as a result of hypertrophied or hyperplastic islet beta cells, later falling glucose levels, and (ii) an unpredictable dissociation of insulin from the complex, and, several hours later, (3) a resultant increase in free insulin levels and severe hypoglycemia with clinical consequences, ranging from sweating, dizziness, headache, and tremors to confusion, seizures, and unconsciousness. These attacks are invariably responsive to glucose administration. This very uncommon manifestation of a monoclonal gammopathy can occur in patients with essential monoclonal gammopathy or myeloma. The monoclonal anti-insulin immunoglobulin in monoclonal gammopathy has a low affinity for insulin, but has a high capacity for insulin-binding, resulting in the syndrome of episodic hypoglycemic attacks. This phenomenon of an insulin-binding monoclonal immunoglobulin simulates the acquired insulin autoimmune syndrome, although the latter is mediated by a polyclonal antibody response in the majority of cases studied, and has linkage to HLA class II alleles.

Approach to the patient with spontaneous hypoglycemia

Hypoglycemia is common in daily clinical practice and often occurs during the treatment of diabetes mellitus. However, a small minority of hypoglycemia encountered in clinical practice is spontaneous and thus not induced by glycemic lowering agents. These spontaneous hypoglycemic events confront the clinician with a diagnostic enigma. Although the trained clinician can recognize the autonomic and neuroglycopenic symptoms of hypoglycemia even in a patient not on insulin, it remains challenging to decipher the etiology of a spontaneous hypoglycemic event. A logical and stepwise approach to the spontaneous hypoglycemic event allows for a conclusive diagnosis. This diagnostic process consists of adequately diagnosing hypoglycemia by fulfilling Whipple's triad, stratifying patients according to their clinical status and analyzing a full hypoglycemic blood panel. A complete hypoglycemic blood panel should include the analysis of glucose, insulin, C-peptide, pro-insulin, insulin antibodies and the presence of oral hypoglycemic agents. For patients with episodes of hypoglycemia induced by excessive endogenous insulin, additional imaging is often required to detect the presence of an underlying insulinoma. By diagnosing the underlying cause of the spontaneous hypoglycemia, the physician also diagnosis the mechanism by which the hypoglycemic event occurs. Allowing for a problem orientated therapeutic approach.

METHODOLOGY

The present review is based upon a comprehensive PubMed search between 1985 and 2013. This uses search terms of spontaneous hypoglycemia, insulinoma, nesidioblastosis, insulin auto-immunity, noninsulinoma pancreatogenous hypoglycemia syndrome, hormone deficiency, pro-IGF II, and pro-insulin growth factor II, and cross reference searching of pivotal articles in the subject.

[Endogenous hyperinsulinism: two diagnostic challenges]

Hypoglycemia in apparently healthy adults is a rare finding in clinical practice requiring a thorough investigation of the cause. During the investigation, identification of hypoglycemia associated with inappropriately high levels of insulin and C-peptide should prompt the exclusion of rare causes of hypoglycemia, including pancreatic islet-cells disease and autoimmune hypoglycemia. In this paper, we describe two cases of hypoglycemia associated with endogenous hyperinsulinism, whose causes are uncommon in clinical practice, and review important aspects of the diagnosis and treatment of hyperinsulinemic hypoglycemia.

Management of endocrine disease: a clinical update on tumor-induced hypoglycemia

Tumor-induced hypoglycemia (TIH) is a rare clinical entity that may occur in patients with diverse kinds of tumor lineages and that may be caused by different mechanisms. These pathogenic mechanisms include the eutopic insulin secretion by a pancreatic islet β-cell tumor, and also the ectopic tumor insulin secretion by non-islet-cell tumor, such as bronchial carcinoids and gastrointestinal stromal tumors. Insulinoma is, by far, the most common tumor associated with clinical and biochemical hypoglycemia. Insulinomas are usually single, small, sporadic, and intrapancreatic benign tumors. Only 5-10% of insulinomas are malignant. Insulinoma may be associated with the multiple endocrine neoplasia type 1 in 4-6% of patients. Medical therapy with diazoxide or somatostatin analogs has been used to control hypoglycemic symptoms in patients with insulinoma, but only surgical excision by enucleation or partial pancreatectomy is curative. Other mechanisms that may, more uncommonly, account for tumor-associated hypoglycemia without excess insulin secretion are the tumor secretion of peptides capable of causing glucose consumption by different mechanisms. These are the cases of tumors producing IGF2 precursors, IGF1, somatostatin, and glucagon-like peptide 1. Tumor autoimmune hypoglycemia occurs due to the production of insulin by tumor cells or insulin receptor autoantibodies. Lastly, massive tumor burden with glucose consumption, massive tumor liver infiltration, and pituitary or adrenal glands destruction by tumor are other mechanisms for TIH in cases of large and aggressive neoplasias.

Recurrent hypoglycemia from insulin autoimmune syndrome

Insulin autoimmune syndrome (IAS) is an uncommon cause of hyperinsulinemic hypoglycemia characterized by autoantibodies to endogenous insulin in individuals without previous exposure to exogenous insulin. IAS is the third leading cause of spontaneous hypoglycemia in Japan, and is increasingly being recognized worldwide in non-Asian populations. We report a case of IAS in a Caucasian woman with recurrent complaints of hypoglycemia, with laboratory findings of serum glucose 2.5 mmol/L (45 mg/dL), insulin 54,930 pmol/L (7,909 μIU/mL), connecting peptide (C-peptide) 4,104 pmol/L (12.4 ng/mL), and a corresponding insulin to C-peptide molar ratio of 13.4 during a spontaneous hypoglycemic event. Autoantibodies to insulin were markedly elevated at > 50 kU/L (> 50 U/mL). IAS should be considered in the differential diagnosis of hypoglycemia in non-diabetic individuals. Distinction from insulinoma is especially crucial to prevent unwarranted invasive procedures and surgical interventions in hypoglycemic patients.

Characterization of insulin antibodies by Surface Plasmon Resonance in two clinical cases: brittle diabetes and insulin autoimmune syndrome

In this study, the characterization of insulin (auto)antibodies has been described, mainly in terms of concentration (q), affinity (K_a) and Ig (sub)isotypes by Surface Plasmon Resonance (SPR) in two particular clinical cases of individuals with severe episodes of impaired glycemia. Subject 1 suffers from brittle diabetes associated with circulating insulin antibodies (IA) due to insulin treatment. Subject 2 has insulin autoantibodies (IAA) associated with hypoglycemia in spite of not being diabetic and not having ever received exogenous insulin therapy. After conventional screening for IA/IAA by radioligand binding assay (RBA), we further characterized IA/IAA in sera of both patients in terms of concentration (q), affinity (K_a) and Ig (sub)isotypes by means of SPR technology. In both cases, q values were higher and Ka values were lower than those obtained in type 1 diabetic patients, suggesting that IA/IAA:insulin immunocomplexes could be responsible for the uncontrolled glycemia. Moreover, subject 1 had a predominat IgG₁ response and subject 2 had an IgG₃ response. In conclusion, SPR technology is useful for the complete characterization of IA/IAA which can be used in special cases where the simple positive/negative determination is not enough to achieve a detailed description of the disease fisiopathology.

Relapsing and remitting severe hypoglycemia due to a monoclonal anti-insulin antibody heralding a case of multiple myeloma

CONTEXT

We report a novel case of insulin autoimmune syndrome (IAS) presenting with hypoglycemia due to production of a monoclonal anti-insulin antibody in a patient subsequently found to have multiple myeloma (MM).

OBJECTIVE

The aim of the study was to describe the 5-yr clinical course of a patient with IAS and MM and to characterize the origin and function of the pathogenic antibody.

METHODS

We conducted a longitudinal case history with laboratory investigations to characterize the anti-insulin antibody subtype, specificity, affinity, and origin.

RESULTS

The patient presented with IAS, which worsened during treatment of hepatitis C. The patient was then discovered to have a monoclonal gammopathy that progressed to MM. Treatment of the MM induced remission of the neoplasia and IAS, which then followed a synchronized course of progression and response to therapy. An anti-insulin IgG(3)-λ that bound specifically but with low affinity to the insulin B chain (amino acids 9-30) and that was distinct from the primary MM IgG(3)-κ clone was recovered from the patient and cloned. The antibody bound insulin and showed mutations of normal affinity maturation.

CONCLUSIONS

We describe a case of MM heralded by IAS, where full characterization of the pathogenic antibody revealed that the monoclonal anti-insulin antibody had originated from a self-reactive clone.

Risk of Japanese carriers of hyperphosphorylated paratarg-7, the first autosomal-dominantly inherited risk factor for hematological neoplasms, to develop monoclonal gammopathy of undetermined significance and multiple myeloma

Hyperphosphorylated paratarg-7 (pP-7) is a frequent target of paraproteins in German patients with monoclonal gammopathy of undetermined significance (MGUS)/multiple myeloma (MM). The frequency of MGUS/MM is lower in Japan than in Europe. As pP-7, the first molecularly defined autosomal-dominant risk factor for any hematological neoplasm, is inherited in a dominant fashion, we determined the incidence of the pP-7 carrier state in a Japanese population, and compared the frequency of pP-7-specific paraproteins and the pP-7 carrier state in Japanese and German patients with MGUS/MM. Peripheral blood from 111 Japanese patients with MGUS/MM and 278 healthy blood donors was analyzed for the pP-7 carrier state by isoelectric focusing and for pP-7-specific antibodies by ELISA. The Japanese group was compared with 252 German MGUS/MM patients and 200 healthy controls. Five of 111 (4.5%) Japanese and 35/252 (13.9%) German IgA/IgG MGUS/MM patients had a pP-7-specific paraprotein (P=0.009). The prevalence of healthy pP-7 carriers in the Japanese study group was 1/278 (0.36%), whereas it was 4/200 in the German group (P=0.166). The relative risk for pP-7 carriers developing MGUS/MM had an odds ratio of 13.1 in the Japanese and 7.9 in the German group. In conclusion, the fraction of pP-7 carriers with a pP-7-specific paraprotein is lower among Japanese than in German patients with MGUS/MM, but pP-7 carriers in both ethnic groups have a high risk of developing MGUS/MM.

Hypoglycemic encephalopathy as the initial presentation of hepatic tumor: a case report

BACKGROUND

Hypoglycemia is a frequently encountered cause of altered mental status in clinical practice.

OBJECTIVES

To report a rare case with hypoglycemia-induced coma as the sole and initial clinical manifestation of a hepatic tumor.

CASE REPORT

A previously healthy 32-year-old man presenting with acute change in consciousness was found to have hepatoma related hypoglycemia.

CONCLUSION

This case highlights the importance of a hepatic evaluation in, otherwise, unexplained hypoglycemic coma in high prevalence areas of hepatocellular carcinoma such as the Asian-Pacific region.

Association of a dominantly inherited hyperphosphorylated paraprotein target with sporadic and familial multiple myeloma and monoclonal gammopathy of undetermined significance: a case-control study

BACKGROUND

Chronic antigenic stimulation might have a role in the pathogenesis of monoclonal gammopathy of unknown significance (MGUS) and multiple myeloma. The aim of this study was to search for factors underlying the autoimmunogenicity of paratarg-7, a frequent antigenic target of paraproteins in MGUS and multiple myeloma.

METHODS

Between January, 2005, and February, 2009, serum and peripheral blood cells were obtained from consecutive patients with MGUS or multiple myeloma and healthy blood donors, and paratarg-7 was analysed by DNA sequencing, SDS-PAGE, isoelectric focusing, and western blotting.

FINDINGS

Mutations or polymorphisms of paratarg-7 were not noted, but hyperphosphorylation was detected in 35 (13.9%) of 252 patients with MGUS or multiple myeloma, all of whom had an anti-paratarg-7-specific paraprotein. Analysis of eight families showed that hyperphosphorylated paratarg-7 is inherited in a dominant fashion, and that carriers of hyperphosphorylated paratarg-7 have an increased risk of developing MGUS and multiple myeloma (odds ratio [OR] 7.9, 95% CI 2.8-22.6; p=0.0001).

INTERPRETATION

Familial MGUS and multiple myeloma were associated with a dominant inheritance of hyperphosphorylated paratarg-7, enabling family members at increased risk for MGUS or multiple myeloma to be identified. That only patients with MGUS or multiple myeloma who are carriers of hyperphosphorylated paratarg-7 had a paratarg-7-specific paraprotein suggests that the hyperphosphorylation of paratarg-7 induces auto-immunity and is involved in the pathogenesis of MGUS and multiple myeloma; for example, by chronic antigenic stimulation.

FUNDING

Förderverein Krebsforschung Saar-Pfalz-Mosel e.V. (eingetragener Verein: officially registered charity) and HOMFOR (the research programme of the Saarland University Faculty of Medicine).

A frequent target of paraproteins in the sera of patients with multiple myeloma and MGUS

Antigenic targets of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) paraproteins might play a role in the pathogenesis of these neoplasms. We screened a human fetal brain-derived macroarray with the IgA or IgG containing sera of 192 consecutive MGUS and MM patients. Twenty-nine of 192 (15.1%) paraproteins reacted with paratarg-7, a protein of unknown function which is expressed in all human tissues. Paratarg-7 reactivity was similarly frequent among IgA and IgG paraproteins, but all paratarg-7 reactive IgG paraproteins belonged to the IgG3 subtype with 24/57 IgG3 (42.1%) paraproteins displaying this specificity. Sequence analysis of paratarg-7 derived from patients having a paraprotein with specificity for paratarg-7 revealed no differences to paratarg-7 derived from patients with paraproteins of other specificities or healthy controls, excluding mutations or polymorphisms as a reason for its autoimmunogenicity. Similarly, Western-blot analysis showed identical bands for paratarg-7 derived from patients and controls. The above-random frequency of paratarg-7 as a paraprotein target suggests that paratarg-7 might be involved in the development of the respective clonal proliferations. The identification of paratarg-7 as an antigenic target enables the more detailed analysis of tumor-host interactions in these patients and their role in the pathogenesis of MM and MGUS.

Autoimmune forms of hypoglycemia

Autoimmune syndromes are a rare cause of hypoglycemia characterized by elevated levels of insulin in the presence of either anti-insulin antibodies (insulin autoimmune syndrome) or anti-insulin receptor antibodies (type B insulin resistance). Insulin autoimmune syndrome is the third leading cause of hypoglycemia in Japan, but has rarely been described in the non-Asian population.In the current study, we report the clinical and biochemical characteristics and clinical course of 2 white patients with insulin autoimmune syndrome, and present a literature review of non-Asian patients reported with insulin autoimmune syndrome. Also, we describe the clinical and biochemical characteristics of patients reported in the literature with type B insulin resistance who manifested hypoglycemia. We compare the clinical and laboratory features of insulin autoimmune syndrome and type B insulin resistance with each other and with other forms of hyperinsulinemic hypoglycemia.Autoimmune forms of hypoglycemia are uncommon. However, they should be considered in any patient with hypoglycemia in the setting of unsuppressed insulin levels associated with anti-insulin or anti-insulin receptor antibodies. Making the correct diagnosis may spare a hypoglycemic patient from an unnecessary pancreatic surgical procedure.

Hypoglycemia following pancreas transplantation

Mild symptoms of hypoglycemia in individuals with type 1 diabetes who have undergone pancreas transplantation are common, but biochemical evidence of hypoglycemia in these individuals often remains scant. Rarely, more overt cases with profound neuroglycopenic symptoms and documented hypoglycemia after transplantation have been described. Although the diagnosis of hypoglycemia in most cases of adrenergic symptoms alone, without documented hypoglycemia, remains questionable and likely not clinically significant, several potential etiologies have been identified in the more severe cases. This article reports a case with severe hypoglycemia after pancreas transplantation for type 1 diabetes, reviews several potential mechanisms underlying pancreas allograft-associated hypoglycemia, and discusses current treatment strategies for minimizing symptomatic hypoglycemia after transplant.

Hypoglycemia due to an insulin binding antibody in a patient with an IgA-kappa myeloma

CONTEXT

Autoantibodies to insulin have been described to cause spontaneous hypoglycemia in nondiabetic subjects. There have been occasional reports of spontaneous hypoglycemia due to monoclonal anti-insulin antibodies. We present the first report of a patient with an IgA-kappa myeloma in whom frequent hypoglycemia resulted from the ability of the monoclonal IgA-kappa to bind insulin.

OBJECTIVES

The aim of this study was to describe the occurrence of profound hypoglycemia in a patient with IgA-kappa myeloma, characterize biochemically the nature of the IgA:insulin complex present, and place this case in the context of the published literature on hypoglycemia resulting from autoantibodies to insulin.

DESIGN

A case study was performed.

PATIENTS

A single case of profound hypoglycemia associated with IgA-kappa myeloma was studied.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURES

A case study was performed.

RESULTS

Polyethylene glycol precipitation and gel filtration chromatography were used to demonstrate high-molecular weight insulin immunoreactivity in the patient's plasma. This was characterized as an insulin binding IgA-kappa paraprotein present at 4200 mg/dl (42 g/liter) with a relatively high insulin dissociation constant of 0.32 microm/liter using radiolabelled insulin binding studies.

CONCLUSIONS

We present the first case of hypoglycemia due to IgA binding insulin antibodies in a patient with an IgA-kappa paraprotein myeloma. The hypoglycemia was associated with high-plasma insulin levels and relatively low C-peptide levels. A plausible mechanism for the hypoglycemia is the delayed clearance of insulin. This case broadens the spectrum of monoclonal gammopathies that have been associated with anti-insulin reactivity and spontaneous hypoglycemia.

Identification of antigenic targets of paraproteins by expression cloning does not support a causal role of chronic antigenic stimulation in the pathogenesis of multiple myeloma and MGUS

Antigenic targets of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) paraproteins have been suggested to play an important role as growth stimulators in the pathogenesis of these neoplasms. To identify such targets, we screened cDNA libraries from human testis, lung and breast cancer, bovine and porcine muscle and wheat germ for reactivity with paraproteins in the sera from 115 patients with MGUS and MM. Of >6 x 10(8) paraprotein-antigen interactions screened, an IgA paraprotein from a female patient bound to sperm-specific cylicin-2, and 3 IgG paraproteins bound to tripeptidyl-peptidase-II (TPP-2), insulin-like growth-factor binding-protein-2 (IGFBP-2) and porcine kinesin. Specificity was confirmed by reverse Western blots using recombinant antigens. The broad spectrum of auto-, allo- and heteroantigens as targets of human paraproteins in patients without signs of chronic antigenic stimulation renders a causal role of the antigenic stimulus in the pathogenesis of MGUS and MM unlikely.

Hypoglycemia

Under physiologic conditions, glucose plays a critical role in providing energy to the central nervous system. A precipitous drop in the availability of this substrate results in dramatic symptoms that signal a medical emergency and warrant immediate therapy aimed at restoring plasma glucose to normal levels. A systemic approach to the differential diagnosis is useful in identifying the cause of hypoglycemia. Once established, a specific and/or definitive intervention that addresses that underlying problem can be implemented. In most cases, this systemic approach to diagnosis and therapy is rewarded with a good outcome for the patient.

The effect of insulin antibodies on the metabolic action of inhaled and subcutaneous insulin: a prospective randomized pharmacodynamic study

OBJECTIVE

To assess the impact of the development of high- or low-affinity insulin antibodies (IABs) on postprandial glucose tolerance, duration of insulin action, and clinical safety in patients with type 1 diabetes receiving inhaled insulin (Exubera).

RESEARCH DESIGN AND METHODS

This study consisted of a prospective, randomized, open-label, parallel-group trial in which 47 patients with type 1 diabetes received NPH insulin twice daily plus either premeal inhaled insulin (INH group; n = 24) or pre-meal subcutaneous regular insulin (SC group; n = 23) for 24 weeks. Meal challenge and euglycemic clamp studies were performed on consecutive days at baseline, week 12, and week 24. Adverse events were monitored.

RESULTS

For the INH and SC groups, mean (+/-SD) IAB levels were 3.5 +/- 3.9 and 2.6 +/- 4.1 muU/ml at baseline, respectively, compared with 101.4 +/- 140.4 and 4.3 +/- 9.4 microU/ml at week 24. At week 24, the changes from baseline were similar for the INH and SC groups for maximal plasma glucose concentration (C(max)) (adjusted ratio for treatment group difference 0.99 [90% CI 0.95-1.03]), area under the plasma glucose concentration time curve (adjusted ratio for treatment group difference 0.98 [0.88-1.08]), and duration of insulin action (adjusted treatment group difference 29 min [-49 to 108]). No adverse events were attributed to IABs.

CONCLUSIONS

In patients with type 1 diabetes treated with inhaled insulin, development of high- or low-affinity IABs did not impair postprandial glucose tolerance, alter the time-action profile of insulin, or impact tolerability. No clinical relevance of IABs was identified in this study.

Insulin Autoimmunity and Hypoglycemia in Seven White Patients

OBJECTIVE

To report the clinical, biochemical, and immunologic characteristics of 7 white patients with the rare disorder of hyperinsulinemic hypoglycemia in association with spontaneously generated high titers of antibodies to human insulin.

METHODS

We reviewed the clinical data, history, and symptoms of the 7 study patients and summarized the biochemical findings during a spontaneous episode of hypoglycemia. Insulin antibody binding was measured in all patients, and antibody affinity, capacity, and clonality were analyzed in 4. A mixed meal study was conducted in 2 patients. A potential mechanism for postprandial hypoglycemia is presented.

RESULTS

In all 7 patients (6 women and 1 man), symptoms were neuroglycopenic, occurring primarily postprandially but during fasting in some patients. During hypoglycemia, concentrations of insulin, proinsulin, and, in most patients, C peptide considerably exceeded those observed in patients with insulinoma. These concentrations were spuriously elevated as a result of interference by the autoantibodies in the immunoassays. No patient had evidence of an insulinoma on various radiologic localization procedures directed at the pancreas. Insulin antibodies showed a high percentage of binding to human insulin--50 to 90%. Heterogeneity of antibodies regarding clonality and antibody binding sites was noted; some patients had polyclonal and some had monoclonal IgG class antibodies. Most patients had two categories of binding sites: high affinity/low capacity and low capacity/high affinity. Although the mechanism for postprandial hypoglycemia remains conjectural, prolonged elevations of postprandial concentrations of total and free insulin are consistent with the putative mechanism of a buffering effect of insulin antibodies.

CONCLUSION

Insulin autoimmune hypoglycemia, although rare in any racial group and especially in white subjects, can be readily detected by high titers of insulin antibodies. Such a determination should be done in all patients undergoing evaluation for hypoglycemia.

Severe hypoglycemic coma due to insulin autoimmune syndrome

Insulin autoimmune syndrome, characterized by the presence of insulin-binding autoantibodies and fasting or late postprandial hypoglycemia, is a rare cause of hypoglycemia. We report a patient with pulmonary tuberculosis who developed recurrent spontaneously post-absorptive hyperinsulinemic hypoglycemia after treatment with anti-tuberculous drugs. Imaging studies of the pancreas were unremarkable, and selective intra-arterial calcium stimulation with hepatic venous sampling for insulin failed to show a gradient, thus almost completely excluding the possibility of occult insulinoma or nesidioblastosis. Examinations of sera, however, disclosed a high titer of polyclonal insulin-binding autoantibodies containing at least 2 classes of binding sites, 1 with high affinity but low capacity, and the other with low affinity but high capacity. An oral glucose tolerance test revealed high serum levels of total insulin associated with relatively low levels of free insulin, but not of C-peptide, suggesting binding of the released insulin to autoantibodies. Regretfully, shortly after the withdrawal of isoniazid, the patient died of respiratory failure unrelated to hypoglycemia, and whether these antibodies were induced by isoniazid remains unknown. We recommend that insulin autoimmune syndrome be one of the differential diagnoses in patients with hyperinsulinemic hypoglycemia.

Severe Autoimmune Hypoglycemia With Insulin Antibodies Necessitating Plasmapheresis

OBJECTIVE

To report a case of autoimmune hypoglycemia.

METHODS

We describe the clinical course of a patient with autoimmune hypoglycemia, including results of biochemical and histocompatibility antigen studies, as well as the therapeutic intervention and follow-up.

RESULTS

A 77-year-old man presented with clinical manifestations of severe spontaneous hypoglycemia associated with extremely high levels of insulin (>300 mU/mL) and insulin antibodies (>100 U/mL) without any exogenous insulin administration. He had no other associated autoimmune disorder or exposure to the sulfhydryl group of drugs. Corticosteroid therapy was initiated, but the patient continued to have hypoglycemia and required plasmapheresis. The hypoglycemia resolved after plasmapheresis. During follow-up, the patient was treated with prednisone, the dose of which was tapered gradually. The insulin antibodies, which had decreased rapidly after plasmapheresis, gradually disappeared within a few months. The patient remained free of hypoglycemia as well as insulin antibodies 11 months after corticosteroid therapy was discontinued.

CONCLUSION

Although autoimmune hypoglycemia is an uncommon disorder, it should be considered in any patient with hypoglycemia in the setting of nonsuppressed insulin levels associated with insulin antibodies.

Insulin production in a neuroectodermal tumor that expresses islet factor-1, but not pancreatic-duodenal homeobox 1

We studied a 60-yr-old female with a brain tumor who showed severe symptoms of hypoglycemia (plasma glucose, 2.2 mmol/L) and hyperinsulinemia (1.28 nmol/L) after radiotherapy. The cystic brain tumor contained proinsulin and insulin at concentrations of 13.6 and 1.22 nmol/L, respectively. Immunohistochemical studies showed the tumor cells were ectodermal in origin but not endodermal, based on three diagnostic features of neuroectodermal tumors 1) pseudorosette formation noted under light microscopy, 2) finding of a small number of dense core neurosecretory granules on electron microscopy, and 3) positive immunostaining for both neuronal specific enolase and protein gene product 9.5. These cells also expressed the transcription factor, neurogenin-3, NeuroD/beta 2, and islet factor I, which are believed to be transcription factors in neuroectoderm as well as in pancreatic islet cells, but not pancreatic-duodenal homeobox 1, Pax4, or Nkx2.2. In addition, they did not express glucagon, somatostatin, or glucagon-like peptide-1. Our results show the presence of proinsulin in an ectoderm cell brain tumor that does not express the homeobox gene, pancreatic-duodenal homeobox 1, but expresses other transcription factors, i.e. neurogenin3, NeuroD/beta 2, and islet factor-1, which are related to insulin gene expression in the brain tumor.

Cationic myeloma M-components frequently show cross-reacting anti-DNA, Anti-F(ab')2 and anti-nucleosome specificities

134 cationic human IgG myeloma proteins were studied for expression of anti-DNA Idiotypic markers. 64 were studied for 16/6, F4, 3I, and 8.12, and 70 for expression of F4 and 3I. 31.3% showed at least one anti-DNA Id marker and many cationic myelomas were also positive for anti-DNA ELISA reactivity as well as anti-F(ab')2. Five M-components showed anti-nucleosome reactivity and one without detectable anti-DNA Id markers showed very strong anti-nucleosome antibody which was also inhibited by DNA and Sm antigens. Anti-idiotypic antisera produced either against Id(+) anti-DNA reactive M components or F(ab')2 fragments of affinity purified SLE IgG anti-DNA showed preferential cross-reactive idiotype reactivity between Id(+) anti-DNA reactive M components. Our findings indicate that human IgG monoclonal proteins positive for several common anti-DNA Ids and possessing anti-DNA ELISA reactivity, can serve as models for SLE Id marker antigens and as a source to prepare anti-Ids from IVIG.

Autoimmune hypoglycemia

Autoimmune hypoglycemia is a rare but fascinating syndrome of hypoglycemia caused by the interaction of endogenous antibodies with insulin or the insulin receptor. Awareness of autoimmune hypoglycemia is important because the syndrome may produce severe neuroglycopenic symptoms and may be confused with the presence of an insulinoma. A correct diagnosis is important to avoid unnecessary surgical intervention in patients who are best treated with conservative support, watchful waiting, or in some cases, immunosuppressive therapy.

Recurrent hypoglycaemia in multiple myeloma: a case of Munchausen syndrome by proxy in an elderly patient

A 73-year-old woman with multiple myeloma experienced four episodes of loss of consciousness, convulsions and profuse sweating whilst she was in the hospital. A thorough investigation in the department of medicine disclosed that with each attack, she had a serum glucose < 1.6 mM L-1, insulin level > 1400 pMol L-1 (N- < 150) and a normal level of serum C-peptide. Since she had no anti-insulin antibodies (which may rarely exist in multiple myeloma), a diagnosis of exogenous injection of insulin was made. A search for a possible perpetrator discovered that the patient had a daughter who was a surgical nurse and who was genuinely concerned whenever she was told that her mother was about to be discharged from the hospital. If she was the perpetrator in the present case, then it is possible that the motive for such an action was to postpone the mother's discharge from hospital. This case is an example of a 'factitious disease by proxy' in an elderly patient. The aim of the present report is to alert the medical personnel to the possibility that Munchausen's syndrome by proxy may also occur in the elderly.

Pathogenic natural anti-cardiolipin antibodies: the experience from monoclonal gammopathy

Anti-cardiolipin antibodies (ACA) were detected in 19% of sera from patients with monoclonal gammopathies (MG). ACA were purified from the sera of patients with MG. One of the IgG-ACA was found to be monospecific with high affinity for cardiolipin, and to carry a pathogenic ACA Id (1.10). Active immunization of naive BALB/c mice with the purified IgG-ACA was followed by production in the mice of sustained high titres of ACA, associated with prolonged activated partial thromboplastin time (APTT) (61 +/- 14s versus 31 +/- 2s in control mice; P < 0.001) and thrombocytopenia (468,000 +/- 224,000/mm3 versus 994,000 +/- 92,000/mm3 in controls; P < 0.001). The titres of other autoantibodies (e.g. anti-DNA, anti-histones), although being high after immunization, decreased rapidly and were undetected after 1 month following the boost injection. The mice immunized with the IgG-ACA exhibited low fecundity (36% of mice became pregnant versus 62% observed in the group immunized with control IgG). The pregnant mice had increased resorption rate (the equivalent of fetal loss in the human) of 52 +/- 8% (versus 5 +/- 4% in the control group). The mean (+/- s.d.) embryo and placental weights in mice with anti-phospholipid syndrome (APLS) were significantly lower compared with the mice injected with control IgG (682 +/- 304 mg and 102 +/- 12 mg versus 1303 +/- 105 mg and 145 +/- 8 mg, respectively; P < 0.001). Serum monoclonal immunoglobulins having autoantibody activity may be regarded as an expansion of clones producing natural autoantibodies. Our results confirm the pathogenic role of natural ACA in the pathogenesis of the anti-phospholipid syndrome.

Reversal of diabetes associated with escape of myeloma: evidence for inappropriate IGF-II secretion

We report the sudden and dramatic reversal of maturity onset diabetes in a 57-year-old woman in association with relapse of IgA myeloma diagnosed 3 years earlier. Prior to the relapse of the myeloma, twice daily insulin had been administered at a dose which had been stable for 3 years. However, the same dose produced hypoglycaemic coma at the time of relapse and, subsequently, blood glucose was controlled by diet alone. There had been no significant change in weight or renal function prior to the hypoglycaemic episode. Investigations showed a suppressed fasting serum insulin level in association with an inappropriately high serum level of IGF-II compared with IGF-I and a 'big' IGF-II concentration at the upper end of the normal range. Pituitary, adrenal and liver disease, as well as the autoimmune insulin syndrome, were excluded. The findings are consistent with the hypothesis that the plasma cell tumour was associated with excessive production of insulin-like peptides with consequent reduction in the blood glucose level.

Longitudinal changes of serum insulin concentration and insulin antibody features in persistent insulin autoimmune syndrome (Hirata's disease)

In a 56-year-old woman with granulomas of gold thioglucose in her hips, who developed insulin autoimmune syndrome, the relationships among the frequency or severity of hypoglycemic attacks, serum insulin (IRI) concentration, and characteristics of insulin antibodies were investigated during the clinical course with steroid treatment and two resection operations for the gold-thioglucose granulomas. When hypoglycemia was severe, the total IRI level was elevated, and Scatchard analysis showed that a high-affinity (k1), low-capacity (b1) population of antibodies had a relatively low affinity constant and very high binding capacity compared with the same population of antibodies in insulin-treated diabetic patients. When the attacks were relieved by steroid treatment and/or granuloma resection operation, the total IRI level was decreased and the high-affinity (k1), low-capacity (b1) population of antibodies showed a higher affinity constant and a lower binding capacity than those during the attacks. This indicated that the antibodies changed their characteristics to release insulin into the serum. The k1/b1 population of insulin antibodies with the lower affinity constant and higher binding capacity may easily release human insulin into the serum, leading to hypoglycemia. The longitudinal change of the k1/b1 population suggests a clonal change of the B cells producing the insulin antibody in insulin autoimmune syndrome.

Hypoglycaemia caused by atypical insulin antibodies in a patient with benign monoclonal gammopathy

We describe a 48-year-old woman with recurrent severe hypoglycaemia apparently caused by a paraprotein with insulin-binding capacity. Very high fasting values were found for serum insulin (170 and > 250 mU l-1) as well as for proinsulin 125 pmol l-1 and an insulinoma was suspected. Hypoglycaemia developed after an oral glucose tolerance (OGTT) test but not during fasting for 48 h. Free insulin and C-peptide were normal during OGTT whereas serum insulin was very high. 125I-insulin binding to serum, determined with a polyethylene glycol (PEG) precipitation method was high (40%), and equally high after addition of 1.7 x 10(-5) mol l-1 cold insulin to estimate non-specific binding. By adding very high concentrations of cold insulin, displacement of 125I-insulin bound to serum was found (50% displacement at 4 x 10(-5) mol l-1). No immunoglobulin G (IgG) insulin antibodies were detected by radioimmunoelectrophoresis. On agarose electrophoresis a small paraprotein (4 g l-1) in the gamma-globulin fraction was detected. 125I-insulin binding to this paraprotein was demonstrated. We conclude that if insulin autoantibodies are suspected as a cause of hypoglycaemia screening for insulin antibodies should always be done with a PEG-precipitation method.

Hypoglycaemia in the adult

Hypoglycaemia is a relatively common cause for referral of patients to the accident and emergency departments of hospitals but most of it is iatrogenic. Occasionally, however, hypoglycaemia is due to any one of up to a hundred different disorders. In some, hypoglycaemia is the cause of intermittent neuroglycopenic symptoms that lead to their referral to medical outpatients for investigation. Only the most important are discussed here. Hyperinsulinism due to abnormal beta-cell function is an uncommon but important cause of spontaneous hypoglycaemia. The diagnosis is suspected from the history of episodes of altered consciousness confirmed by demonstrating raised plasma insulin, C-peptide and proinsulin levels in peripheral blood in the presence of hypoglycaemia. Differentiation of the various causes of endogenous hyperinsulinism before surgery is difficult if not impossible and the low predictive value of most of the localizing techniques that are available makes them an additional and unnecessary cost, producing little clinical benefit. Hypoglycaemia caused by non-islet cell tumours (NICTH) is seemingly rarer than hyperinsulinism from insulinoma and tends to occur in older patients. The clinical features are similar to those of hyperinsulinism but laboratory investigation reveals appropriately depressed plasma insulin, C-peptide and proinsulin levels in the presence of hypoglycaemia. The plasma IGF-II:IGF-I ratio is characteristically high and the concentration of the E-domain of proIGF-II is raised. Autoimmune hypoglycaemia is more common in some countries than others and is most often due to autoantibodies to insulin (AIS). It may also be caused by autoantibodies to the insulin receptor and possibly to autoantibodies that are stimulatory to pancreatic beta-cells. Contrary to popular belief, idiopathic reactive hypoglycaemia is rare and only one of the possible causes of the postprandial syndrome. It is characterized by a low blood glucose concentration in blood collected during a spontaneous symptomatic episode but not at other times. Its cause is unknown. Other causes of hypoglycaemia include endocrinopathies of various kinds; sepsis including malaria; congestive cardiac failure; hepatic and renal insufficiencies; diverse inborn errors of metabolism; and exogenous toxins, of which alcohol is probably the commonest.

[Remission under treatment of cutaneous xanthomatosis disclosing myeloma: apropos of a case with a three-year course]

We report a case of IgG lambda multiple myeloma with inaugural cutaneous xanthomatosis. A three years follow up showed parallel evolution of xanthomatosis and monoclonal gammapathy during therapy suggesting that the association is not coincidental. A decrease in IDL catabolism could be responsible. The monoclonal gammapathy could react with IDL and disturb the recognition of apolipoprotein E by its hepatic receptor.