Hypoglycemia of infancy and nesidioblastosis. Studies with somatostatin

Somatostatin receptors in congenital hyperinsulinism: Biology to bedside

Congenital hyperinsulinism (CHI), although a rare disease, is an important cause of severe hypoglycemia in early infancy and childhood, causing preventable morbidity and mortality. Prompt diagnosis and appropriate treatment is necessary to prevent hypoglycaemia mediated brain damage. At present, the medical treatment of CHI is limited to diazoxide as first line and synthetic somatostatin receptor ligands (SRLs) as second line options; therefore understanding somatostatin biology and treatment perspectives is important. Under healthy conditions, somatostatin secreted from pancreatic islet δ-cells reduces insulin release through somatostatin receptor induced cAMP-mediated downregulation and paracrine inhibition of β- cells. Several SRLs with extended duration of action are now commercially available and are being used off-label in CHI patients. Efficacy remains variable with the present generation of SRLs, with treatment effect often being compromised by loss of initial response and adverse effects such as bowel ischaemia and hepatobiliary dysfunction. In this review we have addressed the biology of the somatostatin system contexualised to CHI. We have discussed the clinical use, limitations, and complications of somatostatin agonists and new and emerging therapies for CHI.

Case report: A particularly rare case of endogenous hyperinsulinemic hypoglycemia complicated with pregnancy treated with short-acting somatostatin analog injections

Hyperinsulinemic hypoglycemia is a rare disease, and only two cases complicated with pregnancy were published previously when our patient became pregnant. We introduce a successful management of a pregnancy in a patient with endogenous hyperinsulinemic hypoglycemia, a condition also known as non-insulinoma pancreatogenous hypoglycemia syndrome or formerly as nesidioblastosis. A 29-year-old female patient was treated with endogenous hyperinsulinemic hypoglycemia since the age of 4 months, taking daily 3 × 75 mg diazoxide, which adds up to 225 mg per day. Adequate glycemic control could be achieved with this therapy. Genetic testing and various imaging examinations were carried out earlier to specify the disease and to exclude focal forms. The patient came to the clinic with a positive pregnancy test and consequential hypoglycemic episodes. Hospital admission was needed to correct the metabolic condition. Although the patient was informed about the potential risks, she decided to carry out the pregnancy. According to the quite limited literature, somatostatin analogs are the only therapy used previously during pregnancy in hyperinsulinemic hypoglycemic patients. One publication reported normal pregnancy outcomes, but in another case, restricted fetal growth was observed. In our case, we stopped diazoxide and parallelly introduced short-acting somatostatin analog octreotide in the therapy, and further dietetic changes were proposed. In addition to daily regular self-blood glucose monitoring, regular gynecological controls were carried out monthly, and healthy fetal development was confirmed. The patient gave birth to her first child, a well-developed female neonate, in the 38th week, by a cesarean section.

Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia

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

Hyperinsulinism in the Neonate

Hyperinsulinism (HI) is the leading cause of persistent hypoglycemia in infants. Prompt recognition and treatment, independent of whether infants have transient or permanent HI, are essential to decrease risk of neurologic damage. The most common form of congenital HI is due to inactivating mutations of the β-cell ATP-sensitive potassium (K_ATP) channel (K_ATP-HI) and is typically diazoxide unresponsive. K_ATP-HI occurs in diffuse and focal forms. Distinguishing between the 2 forms is crucial, because pancreatectomy is curative in the focal form but palliative in the diffuse form. The 18-fluoro-L-3,4-dihydroxyphenylalanine PET scan has revolutionized HI management by allowing accurate localization of focal lesions prior to surgery.

Long-term medical treatment in congenital hyperinsulinism: a descriptive analysis in a large cohort of patients from different clinical centers

BACKGROUND

Up to now, only limited data on long-term medical treatment in congenital hyperinsulinism (CHI) is available. Moreover, most of the drugs used in CHI are therefore not approved. We aimed to assemble more objective information on medical treatment in CHI with regard to type and duration, dosage as well as side effects.

METHODS

We searched MEDLINE (from 1947) and EMBASE (from 1988) using the OVID interface for relevant data to evaluate medical treatment in a large cohort of patients with CHI from different clinical centers. Randomized, controlled trials were not available. We evaluated case reports and case series. No language restrictions were made.

RESULTS

A total number of 619 patients were medically treated and information regarding conservative treatment was available. Drugs used were diazoxide (in 84% of patients), somatostatin analogues (16%), calcium channel antagonists (4%) and glucagon (1%). Mean dose of diazoxide was 12.5 (±4.3) mg/kg ⋅ d (range 2-60 mg/kg ⋅ d), mean duration of diazoxide treatment until remission was 57 months. Side effects of diazoxide were usually not severe. The causal relation between diazoxide and severe side effects, e.g. heart failure (3.7%) remains doubtful. Mean dose of octreotide was 14.9 (±7.5) μg/kg ⋅ d (range 2.3-50 μg/kg ⋅ d), of lanreotide 67.3 (±39.8) mg ⋅ month (range 10-120 mg ⋅ month). Mean duration of treatment with somatostatin analogues until remission was 49 months. Frequent side effects included tachyphylaxis and mild gastrointestinal symptoms. The risk of persistent growth deceleration was low (<5%).

CONCLUSIONS

Severe side effects are rare and a causal relation remains disputable. We conclude that long-term conservative treatment of CHI is feasible.

Monogenic hyperinsulinemic hypoglycemia: current insights into the pathogenesis and management

Hyperinsulinism (HI) is the leading cause of persistent hypoglycemia in children, which if unrecognized may lead to development delays and permanent neurologic damage. Prompt recognition and appropriate treatment of HI are essential to avoid these sequelae. Major advances have been made over the past two decades in understanding the molecular basis of hyperinsulinism and mutations in nine genes are currently known to cause HI. Inactivating K_ATP channel mutations cause the most common and severe type of HI, which occurs in both a focal and a diffuse form. Activating mutations of glutamate dehydrogenase (GDH) lead to hyperinsulinism/hyperammonemia syndrome, while activating mutations of glucokinase (GK), the “glucose sensor” of the beta cell, causes hyperinsulinism with a variable clinical phenotype. More recently identified genetic causes include mutations in the genes encoding short-chain 3-hydroxyacyl-CoA (SCHAD), uncoupling protein 2 (UCP2), hepatocyte nuclear factor 4-alpha (HNF-4α), hepatocyte nuclear factor 1-alpha (HNF-1α), and monocarboyxlate transporter 1 (MCT-1), which results in a very rare form of HI triggered by exercise. For a timely diagnosis, a critical sample and a glucagon stimulation test should be done when plasma glucose is < 50 mg/dL. A failure to respond to a trial of diazoxide, a K_ATP channel agonist, suggests a K_ATP defect, which frequently requires pancreatectomy. Surgery is palliative for children with diffuse K_ATPHI, but children with focal K_ATPHI are cured with a limited pancreatectomy. Therefore, distinguishing between diffuse and focal disease and localizing the focal lesion in the pancreas are crucial aspects of HI management. Since 2003, ¹⁸ F-DOPA PET scans have been used to differentiate diffuse and focal disease and localize focal lesions with higher sensitivity and specificity than more invasive interventional radiology techniques. Hyperinsulinism remains a challenging disorder, but recent advances in the understanding of its genetic basis and breakthroughs in management should lead to improved outcomes for these children.

The added value of [18F]fluoro-L-DOPA PET in the diagnosis of hyperinsulinism of infancy: a retrospective study involving 49 children

PURPOSE

Neuroendocrine diseases are a heterogeneous group of entities with the ability to take up amine precursors, such as L-DOPA, and convert them into biogenic amines, such as dopamine. Congenital hyperinsulinism of infancy (HI) is a neuroendocrine disease secondary to either focal adenomatous hyperplasia or a diffuse abnormal pancreatic insulin secretion. While focal hyperinsulinism may be reversed by selective surgical resection, diffuse forms require near-total pancreatectomy when resistant to medical treatment. Here, we report the diagnostic value of PET with [(18)F]fluoro-L-DOPA in distinguishing focal from diffuse HI.

METHODS

Forty-nine children were studied with [(18)F]fluoro-L-DOPA. A thoraco-abdominal scan was acquired 45-65 min after the injection of 4.2 +/- 1.0 MBq/kg of [(18)F]fluoro-L-DOPA. Additionally, 12 of the 49 children were submitted to pancreatic venous catheterisation for blood samples (PVS) and 31 were also investigated using MRI.

RESULTS

We identified abnormal focal pancreatic uptake of [(18)F]fluoro-L-DOPA in 15 children, whereas diffuse radiotracer uptake was observed in the pancreatic area in the other 34 patients. In children studied with both PET and PVS, the results were concordant in 11/12 cases. All patients with focal radiotracer uptake and nine of the patients with diffuse pancreatic radiotracer accumulation, unresponsive to medical treatment, were submitted to surgery. In 21 of these 24 patients, the histopathological results confirmed the PET findings. In focal forms, selective surgery was followed by clinical remission without carbohydrate intolerance.

CONCLUSION

These data demonstrate that PET with [(18)F]fluoro-L-DOPA is an accurate non-invasive technique allowing differential diagnosis between focal and diffuse forms of HI.

Fetal macrosomia: etiologic factors

Fetal growth can be considered the outcome of an interaction between the genetic cause of growth and constraints provided by limitations on substrate availability (selected amino acids, free fatty acids, and mainly glucose). It should be noted that the majority of large infants are constitutionally large and do not require special intervention, which will result in adverse perinatal outcome. Efforts should be directed to the accelerated (pathologic) overgrown fetus and to methods of primary prevention of this abnormality by appropriate management approaches for the mother and fetus.

Focal and Diffuse Beta Cell Changes in Persistent Hyperinsulinemic Hypoglycemia of Infancy

In recent years our understanding of the changes in the endocrine pancreas in persistent hyperinsulinemic hypoglycemia in infancy, a form of congenital hypoglycemia, has increased considerably, in terms of both morphological classification and molecular pathogenesis. This review summarizes the current state of knowledge about the pathological lesions in the pancreas and their relationship to recently reported molecular findings.

Neonatal hyperinsulinemic hypoglycemia: heterogeneity of the syndrome and keys for differential diagnosis

The two major forms of infantile persistent hyperinsulinemic hypoglycemia require different treatments, but are difficult to differentiate during surgery. Indeed, one is characterized by focal adenomatous hyperplasia often macroscopically invisible, whereas the other consists of a diffuse, but discreet, beta-cell abnormality. We evaluated, in a large series of persistent hyperinsulinemic hypoglycemia, the reliability of two criteria in differentiating these two forms: the mean beta-cell nuclear radius (MNR) and the beta-cell nuclear crowding, i.e. the number of nuclei per 1000 micron 2 beta-cell (BCNC). The values of the largest MNR and of BCNC in cases bearing a focal lesion (respectively, 3.27 microns +/- 0.25 and 14.62 +/- 1.78) were significantly different from those in the diffuse pathology (4.25 microns +/- 0.43 and 10.00 +/- 1.55). Setting the threshold value of MNR at 3.70 microns and that of BCNC at 12.00 enabled correct classification of 90.9% of the diffuse and 100% of the focal forms. beta-Cell nuclear analysis can thus contribute to a subclassification of the syndrome, not allowed by clinical or biological data. If performed during surgery it could help in determining the extent of pancreatectomy necessary to cure the patient, as the diffuse form, with abnormal nuclei in the whole pancreas, requires subtotal to near-total pancreatectomy, whereas the focal form, devoid of abnormal insular beta-cell nuclei, can be cured by partial pancreatectomy.

Therapy for persistent hyperinsulinemic hypoglycemia of infancy. Understanding the responsiveness of beta cells to diazoxide and somatostatin

The neonatal disorder persistent hyperinsulinemic hypoglycemia of infancy (PHHI) arises as the result of mutations in the subunits that form the ATP-sensitive potassium (KATP) channel in pancreatic beta cells, leading to insulin hypersecretion. Diazoxide (a specific KATP channel agonist in normal beta cells) and somatostatin (octreotide) are the mainstay of medical treatment for the condition. To investigate the mechanism of action of these agents in PHHI beta cells that lack KATP currents, we applied patch clamp techniques to insulin-secreting cells isolated from seven patients with PHHI. Five patients showed favorable responses to medical therapy, and two were refractory. Our data reveal, in drug-responsive patients, that a novel ion channel is modulated by diazoxide and somatostatin, leading to termination of the spontaneous electrical events that underlie insulin hypersecretion. The drug-resistant patients, both of whom carried a mutation in one of the genes that encode KATP channel subunits, also lacked this novel K+ channel. There were no effects of diazoxide and somatostatin on beta cell function in vitro. These findings elucidate for the first time the mechanisms of action of diazoxide and somatostatin in infants with PHHI in whom KATP channels are absent, and provide a rationale for development of new therapeutic opportunities by K+ channel manipulation in PHHI treatment.

Pancreatic glucagon levels in infants and children with hyperinsulinemia

Serum concentrations of pancreatic glucagon were measured in 40 patients with hyperinsulinemic hypoglycemia. In infants with severe disease the glucagon levels were markedly elevated; lower levels were observed in children with episodic hypoglycemia. During diazoxide treatment and after pancreatectomy, the glucagon levels decreased proportionally to suppression of the insulin secretion. Thus the secretion of glucagon seems to be retained in hyperinsulinism in proportion to the insulin hypersecretion, and an increased glucagon level indicates long during and severity of hyperinsulinemic hypoglycemia.

Persistent hyperinsulinemic hypoglycemia of infancy: long-term octreotide treatment without pancreatectomy

Eight patients with persistent hyperinsulinemic hypoglycemia of infancy who were treated with octreotide without pancreatectomy are described. All had severe, early-onset disease that would have required partial pancreatectomy had octreotide not been available. Along with octreotide, frequent feedings and raw cornstarch at night were required by all. Octreotide was given in three or four daily subcutaneous injections in four patients and in a continuous subcutaneous infusion with an insulin infusion pump in four. All had mild, transient gastrointestinal symptoms (vomiting, abdominal distention, steatorrhea) after the start of therapy. Asymptomatic gallstones were found in 1 patient after 1 year of treatment. No other long-term untoward effects were noted, including no detrimental effect on psychomotor development. Growth was not affected in five of six patients treated for more than 6 months. In five patients, octreotide was discontinued after 9 months to 5 1/2 years; patients were given diazoxide instead, two required percutaneous gastrostomy, and one 5 1/2-year-old child required no further treatment. The remaining three patients (aged 5 to 9 months) are still being treated with octreotide. We conclude that, with the use of octreotide, pancreatectomy can be avoided in some patients. Particularly in light of our findings of a high incidence of diabetes years after partial pancreatectomy, and clinical improvement after months to years of octreotide treatment, we believe that aggressive medical therapy, when effective, is preferable to partial pancreatectomy.

Short- and long-term use of octreotide in the treatment of congenital hyperinsulinism

Octreotide, a long-acting analog of somatostatin that inhibits insulin release, has the potential to control hypoglycemia in infants with congenital hyperinsulinism. To examine the efficacy and side effects of octreotide, we evaluated therapy between 1988 and 1993 in 16 infants who did not respond to diazoxide. In nine patients with onset of severe hypoglycemia in the first days of life, octreotide was helpful in stabilizing plasma glucose levels and allowed reductions in the rates of glucose infusion; however, glucose control was inadequate to avoid subtotal pancreatectomy. In two of these nine patients postoperatively and in seven other infants, a trial of long-term treatment with octreotide was undertaken. Four were treated successfully for up to 4.3 years. Octreotide therapy was not associated with thyroid deficiency and caused only transient malabsorption. All patients receiving long-term therapy had some decrease in linear growth and two had subnormal plasma concentrations of insulin-like growth factor I and insulin-like growth factor binding protein 3 compatible with suppression of growth hormone by octreotide. Resistance to octreotide therapy, even with increasing doses, occurred in all patients. These results suggest that octreotide may aid in the acute or long-term treatment of congenital hyperinsulinism in a limited number of selected cases.

Tolerance to somatostatin analogue in a preterm infant with islet cell dysregulation syndrome

An infant of 31 weeks' gestation presented with refractory neonatal hypoglycaemia secondary to islet cell dysregulation. Treatment was started with somatostatin analogue and his glycaemic control improved initially. Tolerance developed, however, in that the dose required to maintain control increased by a factor of 40. The infant subsequently underwent pancreatectomy. It is safe to use somatostatin analogue in a preterm infant, but tolerance to the drug rapidly develops.

Hyperplasia of somatostatin and pancreatic polypeptide immunoreactive cells in dogs with idiopathic atrophy of the exocrine pancreas

The pancreatic tissue from 25 dogs with idiopathic atrophy of the exocrine pancreas, and from 6 control dogs, was studied histologically and immunohistometrically. Cells producing insulin (B), glucagon (A), somatostatin (D), and pancreatic polypeptide (PP) were identified using specific antisera and the ABC technique. Histometrical quantitation revealed differences in the distribution of these cell types between the right and left pancreatic lobe. Initial stages of atrophy showed little changes concerning the relative proportions of the four cell types examined. In more advanced stages of atrophy, however, there was significant increase in the percentage of the D cells in the cell population of the left lobe. B and A cells showed no significant changes. In final stages, only tiny tissue spots were considered a secondary and regenerative phenomenon, but an endocrine dysregulation cannot be excluded. Atrophy accompanied by diabetes mellitus and a lack of B cells seem to be due to a deficiency of insulin.

Persistent hyperinsulinemic hypoglycemia of infancy ("nesidioblastosis"): autosomal recessive inheritance in 7 pedigrees

Persistent Hyperinsulinemic Hypoglycemia of Infancy (PHHI) is a rare disease characterized clinically by persistent hypoglycemia with inappropriately elevated circulating insulin concentrations. Here we report on 7 pedigrees including 21 cases. The pedigrees are derived from 3 distinct ethnic groups, and include a very large Bedouin family, and Arab family, and 5 smaller pedigrees of Jewish families all of Eastern European origin. Data obtained from these families and from other families reported in the literature strongly suggest that PHHI is inherited as an autosomal recessive disorder.

Regulation of insulin release in persistent hyperinsulinaemic hypoglycaemia of infancy studied in long-term culture of pancreatic tissue

Pancreatic tissue was obtained during therapeutic subtotal pancreatectomy from five infants with persistent hyperinsulinaemic hypoglycaemia of infancy (so-called nesidioblastosis). Collagenase digests of the specimens were cultured in RPMI 1640 medium on extracellular matrix-coated plates. Acute insulin secretion showed minimal sensitivity to changes in glucose concentration. Sensitivity to other nutrient secretagogues such as glyceraldehyde, leucine, alpha-ketoisocaproic acid and arginine was variable, showing either diminished or absent response. On the other hand, stimulators of Beta cell cAMP and modulators of the phosphoinositide-protein kinase C pathway were effective inducers of insulin release. The response to cAMP stimulators was independent of the glucose concentration. Although insulin output was high in the absence of glucose, this was not due to passive leak of hormone, since both removal of calcium and addition of somatostatin and epinephrine inhibited the secretion. Beta cells were more sensitive to somatostatin than epinephrine; however, both agents failed to completely suppress the release even at suprapharmacological concentrations. Although it cannot be excluded that the culture conditions affected Beta cell function, the present findings may suggest that cultured Beta cells in persistent hyperinsulinaemic hypoglycaemia of infancy behave like fetal Beta cells at early developmental stages.

Persistent hyperinsulinaemic hypoglycaemia of infancy: long-term treatment with the somatostatin analogue Sandostatin

Six infants with severe, persistent hyperinsulinaemic hypoglycaemia were treated with the long-acting somatostatin analogue SMS 201-995 (Sandostatin, Sandoz, Basle, Switzerland). Effective control of hypoglycaemia without the need for parenteral glucose was achieved in five of the six cases with doses ranging from 10 to 40 micrograms/kg day given either by four s.c. injections per day, or by continuous subcutaneous infusion (CSI). One has been well controlled on SMS 10 micrograms/kg day for 17 months as an out-patient without requiring surgery, while the five others underwent sub-total pancreatectomy after receiving short courses of the drug. In two patients where hypoglycaemia persisted after sub-total pancreatectomy SMS was effective in inhibiting insulin secretion and preventing hypoglycaemia. Plasma somatomedin concentrations and linear growth were not suppressed in any patient. It is concluded that Sandostatin is useful in the pre and post-operative management of most infants with this syndrome. In selected cases this analogue of somatostatin may also be a long-term treatment option in place of pancreatectomy.

Hyperinsulinism in infancy

Five infants with persistent hypoglycaemia due to hyperinsulinism were reported. Provocative tests for insulin release were unhelpful. Diazoxide was useful in the treatment of three patients but many side-effects were observed. These included petechial rash, hypertrichosis, acute renal failure, fluid retention and cardiac failure. Two patients underwent spontaneous remission. Three patients had nesidioblastosis, two of whom were subjected to 95% pancreatectomy. Postoperatively, recurrence of hypoglycaemia was due to hyperinsulinism in one patient and to presumed glucagon deficiency in the other. Phenytoin effectively corrected the hypoglycaemia in the patient who had postoperative hyperinsulinism. It is recommended that medical therapy with diazoxide (10-15 mg/kg per day) together with a diuretic be commenced once hyperinsulinism is diagnosed. Subtotal pancreatectomy should be performed early in these patients if hypoglycaemia cannot be controlled with medical therapy or if side-effects of treatment are documented.

Somatostatin analogue in short term management of hyperinsulinism

Five infants with hypoglycaemia due to hyperinsulinism were treated for between three and 11 days with a somatostatin analogue, which raised the mean blood glucose concentration and lowered the glucose requirements in all. Somatostatin analogue appears to be useful in the short term management of these patients.

Insulin-like growth factors and insulin increase the contractility of neonatal rat cardiocytes in vitro

In the newborn several situations of hyperinsulinism can be associated with myocardial hypertrophy and increased contractility. Insulin and the insulin-like growth factors (IGF) are derived from a common ancestral molecule. Insulin exerts mainly metabolic action, whereas the IGFs promote cell multiplication and differentiation. Using an assay system of cultured neonatal myocardial cells the stimulatory action of insulin and the insulin-like growth factors I and II on myocardial cell contractility was investigated. Spontaneously beating aggregates of myocardial cells were synchronized by an electric impulse generator. Contractility was measured via the amplitude of contraction by an optoelectronic system. Insulin at a concentration of 6,250 and 12,500 microU/ml increased the contractility by 11 and 18%; IGF-I at a concentration of 12 and 25 ng/ml, and IGF-II at a concentration of 25 and 50 ng/ml increased the contractility by 16 and 22%, and 13 and 18%, respectively. Lower concentrations did not provoke a significant increase in contractility. Insulin only in supraphysiological doses increases the contractility of neonatal myocardial rat cells, whereas both insulin-like growth factors act in physiological concentrations. Therefore, during hyperinsulinism insulin may increase myocardial contractility via the IGF receptor and not via the insulin receptor.

Long-term use of somatostatin analogue SMS 201-995 in the treatment of hypoglycaemia due to nesidioblastosis

An infant presented with hypoglycaemia secondary to nesidioblastosis. Subtotal pancreatectomy failed to prevent recurrent post-operative hypoglycaemia. Subcutaneous somatostatin analogue (SMS 201-995) was shown to increase the blood concentrations of glucose and B-hydroxybutyrate while lowering serum insulin levels. Regular use of somatostatin analogue was helpful in long term management without causing significant side effects.

Studies on insulin secretion by monolayer cultures of normal and tumorous human pancreatic cells. Effects of glucose, somatostatin and SMS 201-995

Recently, somatostatin analogs have been introduced which can be used clinically in the treatment of tumorous or functional hypoglycemia. In the present study we investigated in vitro the regulation, the degree of autonomy and the sensitivity to natural somatostatin and its analog SMS 201-995 of insulin secretion by monolayer cultures of human pancreatic cells obtained from patients with insulinomas and from a newborn with nesidioblastosis. All cultures released insulin upon the addition of dibutyryl-cAMP and calcium, demonstrating their intact viability. Insulin secretion from nontumorous pancreatic cells surrounding an insulinoma was dose-dependently stimulated by glucose. In contrast, insulin release by B cells from a patient with nesidioblastosis and from 2 insulinomas was not stimulated by the addition of glucose. Native somatostatin (SRIF) and the synthetic analog SMS 201-995 inhibited insulin secretion from all cultures. The inhibitory effects of SRIF and SMS in the culture from the nesidioblastosis tissue, could be reversed by the addition of 11.2 mmol glucose/l, but not in one of the insulinoma cultures. This demonstrates that some sensitivity to glucose is present in B cells from the nesidioblastosis tissue, despite the unresponsiveness to glucose alone. Insulin release by insulinoma cells was blocked by somatostatin, while it was inhibited to some extent only in the cultures of nontumor B cells and of cells from the nesidioblastosis tissue. In conclusion, it was shown that insulin release by the cultured B cells obtained from several pathological conditions differed with regard to the autonomy of hormone release (glucose sensitivity) and the sensitivity to somatostatin and its analog.

Hypoglycemia of infancy and childhood

Hypoglycemia of infancy and childhood represents a treatable cause of mental retardation and seizures. Most neonates with hypoglycemia have transient disorders, but with persistent hypoglycemia one must consider hyperinsulinism, hypopituitarism, or hereditary hepatic enzyme deficiencies. Outside of the neonatal period, ketotic hypoglycemia is the most common cause of hypoglycemia in childhood. One cannot overemphasize the value of obtaining certain diagnostic tests at the presentation of spontaneous hypoglycemia, including blood for insulin, cortisol, growth hormone, and urine for ketone bodies. Supportive treatment with intravenous glucose to maintain the blood glucose greater than 50 mg/dl is important until a diagnosis is established allowing specific therapy aimed at the underlying disorder.

Pharmacological studies of somatostatin and somatostatin-analogues: therapeutic advances and perspectives

This article is aimed at reviewing and analyzing studies that are related to the possible therapeutic use of a potent and ubiquitously-distributed hormone--somato-statin (SS-14), and its analogues. Administration of these substances has provided beneficial effects in treating acromegaly, gastro-intestinal hemorrhagic and hypersecretory disorders, acute pancreatitis, diabetes mellitus, and certain types of cancer. Further studies with SS-14-analogues might provide new therapies for treating certain life-threatening disorders of man.

An immunohistochemical study of islet cells with macronuclei in infancy

The presence of hypertrophic islet cells in infancy as evidenced by nuclear enlargement (2 to 6 times normal size) has been mentioned as a morphological accompaniment of hyperinsulinemic hypoglycemia of infancy. We report an immunohistochemical and semiquantitative study of hypertrophic islet cells in 14 infants with neonatal hypoglycemia (10 with documented persistent neonatal hypoglycemia and 4 with probable persistent neonatal hypoglycemia) and 6 infants born to diabetic mothers (IDM), using an indirect immunoperoxidase methods for the demonstration of insulin, somatostatin, and glucagon. Quantitation of immunoreactivity was performed in each case on 20 hypertrophic cells. Polyploid cells were positive for insulin and somatostatin but negative for glucagon; insulin-positive cells outnumbered somatostatin-positive cells in both groups. As nuclear hypertrophy is considered to be a sign of hyperfunction, our findings are in accordance with the concept that IDM involves reactive beta-cell hypertrophy and similar findings in the pancreases of infants with persistent neonatal hypoglycemia (PNH) suggest a primary dysfunction of their beta cells, too.

Somatostatin analogue (SMS 201-995) in the management of gastroenteropancreatic tumors and diarrhea syndromes

SMS 201-995 (Sandostatin) was studied using low doses (50 to 100 micrograms) administered subcutaneously every 12 hours. A single 50-micrograms dose of SMS 201-995 effectively controlled gastric acid and blood gastrin levels for 12 hours in three patients with benign gastrinomas and was useful in their perioperative management. Higher doses of the agent (500 to 800 micrograms per day) had no effect on metastases in one of two patients with metastatic gastrinoma. In the other patient, one tumor shrank but the other continued to grow after three months of treatment while serum gastrin levels did not change. Cultured metastatic tumor tissue from this patient released different forms of gastrin; growth rates varied, independent of uptake of SMS 201-995, and gastrin release increased. A neonate with nesidioblastosis maintained normal blood glucose levels while receiving SMS 201-995 therapy following a 95 percent pancreatic resection. In two elderly patients with organic hypoglycemia--one with a single benign adenoma and one with multiple adenomatosis--the somatostatin analogue did not prolong the hypoglycemia-free interval. In nine patients with carcinoid syndrome, flushing was uniformly controlled with 50 micrograms of SMS 201-995 administered every eight to 12 hours. One of the nine required exocrine pancreatic replacement. After six months of treatment, three of the nine had no change in tumor size and one had remission of symptoms and stopped treatment. In two patients with vipoma, SMS 201-995 controlled diarrhea and reduced levels of vasoactive intestinal peptide; tumor necrosis occurred in one patient. In a patient with diabetic diarrhea unresponsive to all treatments, SMS 201-995 therapy controlled the diarrhea but did not interfere with control of the diabetes.

Effects of somatostatin analogue SMS 201-995 in normal man

Long-acting somatostatin analogues may be of benefit in certain hypersecretory endocrine and gastrointestinal disorders. The 24 h hormonal and metabolic profiles of six normal male subjects receiving a twice daily subcutaneous injection of one such analogue SMS 201-995, 50 micrograms, has been compared to that obtained following placebo injection. Spontaneous daytime peaks of GH secretion were delayed until 1400 h following SMS 201-995 but nocturnal and total 24 h GH secretion were unaffected. The nocturnal rise in thyrotrophin was abolished by SMS 201-995 but thyroid function was unaffected. Insulin levels were suppressed following SMS 201-995 and the response to meals was inhibited. Glucose intolerance followed main meals. Glucagon levels were suppressed for up to 6 h. Circulating alanine levels were raised between 1200 h and 0600 h and there were intermittent elevations in lactate, pyruvate, glycerol and 3-hydroxybutyrate. Amino acid levels, including branched chain amino acids, were also increased. All six subjects suffered gastrointestinal side-effects. SMS 201-995, 50 micrograms, given twice daily shortly before meals does not suppress 24 h GH secretion, but demonstrates significant effects on metabolism and causes side effects in normal subjects.

Islet cell hyperplasia: an unusual cause of hypoglycemia in an adult

This is a case presentation of a 32-year-old man with a one year history of symptomatic hypoglycemia and documented elevations of his fasting plasma insulin to glucose ratio, caused by islet cell hyperplasia. Islet cell hyperplasia is a common cause of hypoglycemia in the pediatric population, but is very rare in adults. As in the pediatric group, adults should be treated with subtotal (75-85%) resection of the pancreas and with diazoxide for symptomatic recurrence of hypoglycemia. We suggest that the term islet cell hyperplasia is preferred to designate a diffuse proliferation of endocrine cells that may express itself with different morphologic patterns, varying from case to case. Islet cell hyperplasia, therefore, comprises nesidioblastosis, endocrine cell budding from ductal structures, as well as islet and islet cell hypertrophy, septal islets, islet dysplasia, and adenomatosis. Immunohistochemistry is a valuable method for the demonstration of the polymorphic hormonal content of the proliferated islet cells. We propose that the term nesidioblastosis, previously used to describe some similar cases, should be avoided because of confusion about its definition.

Effect of calcitonin on gastrointestinal regulatory peptides in man

A major physiological role of calcitonin in humans appears to be regulation of skeletal turnover. It has been suggested that another function of calcitonin is to prevent post-prandial rises in calcium, particularly in animals, but the importance of such a function in man remains to be determined. Although it is known that calcitonin has an inhibitory effect on the secretion of gastrin and insulin, its actions on other gut and pancreatic hormones have not previously been studied. To investigate interrelations between calcitonin and gastrointestinal regulatory peptides, 0.5 mg synthetic human calcitonin was administered to 10 fasting patients. No changes in the plasma concentrations of glucose, somatostatin, neurotensin, enteroglucagon, vasoactive intestinal polypeptide or bombesin were observed. In contrast, profound falls in the circulating levels of gastrin, insulin and pancreatic glucagon were seen, reaching a maximum shortly after the peak of plasma calcitonin concentration. Marked changes were also observed in the levels of motilin, pancreatic polypeptide and, to a lesser extent, gastric inhibitory polypeptide, but the maximal falls occurred about 40 min later, coinciding with a significant fall in serum calcium. It is possible that the effect of calcitonin on these hormones was direct, perhaps receptor-mediated. The falls in levels of motilin and pancreatic polypeptide could have been further enhanced by changes in extracellular calcium ion concentrations. Whether any of these effects of calcitonin occur physiologically remains to be determined. However, these findings suggest new therapeutic possibilities for calcitonin.

Somatostatin and the dumping syndrome

Infusion of somatostatin reduced the symptoms of the early dumping syndrome after oral glucose was given and also reduced the associated tachycardia and rise in packed cell volume. It inhibited the secretion of enteroglucagon, neurotensin, and vasoactive intestinal polypeptide, which are raised in patients with the dumping syndrome and may have an aetiological role. It also prevented the reactive hypoglycaemia of late dumping by inhibiting the release of gastric inhibitory polypeptide and insulin. Somatostatin, possibly through its inhibitory effects on hormonal secretion, may have a role in the management of patients with the early and late dumping syndrome.

Experience with 95% pancreatectomy and splenic salvage for neonatal nesidioblastosis

Conventional 85% pancreatectomy with splenectomy performed for management of hypoglycemia of neonatal nesidioblastosis has been followed by a dismal prognosis characterized by post-splenectomy sepsis, recurrent hypoglycemia, permanent brain damage, and a high mortality. For our last eight infants we have found it possible to remove at least 95% of the pancreas, preserving the blood supply to the spleen as well as the duodenum. This has permitted satisfactory control of the hypoglycemia and long-term septic complications have been avoided. Follow-up evaluation up to 20 years with successful control of hypoglycemia without progressive brain damage indicates the value of this primary extensive surgical approach.

Treatment of hypoglycemia in infants and children. Surgical considerations

Pancreatic resection was required in 11 pediatric patients over a 14 year period for control of persistent hypoglycemia. A standard surgical approach based on pathologic considerations was utilized. A subtotal distal pancreatectomy, liver biopsy, and removal of additional adenomatous tissue when found was performed in each patient. This approach precluded the need for routine preoperative visceral angiography, which is currently reserved for patients who require a second exploration. Surgery was curative in patients with adenomatous disease, although patients with diffuse pancreatic lesions usually required continued pharmacologic therapy postoperatively. Two patients thus far have had a total pancreatectomy performed at a second laparatomy due to persistent intractable disease. Seizure disorders, mental retardation, and behavioral problems frequently were unresponsive to improved control of hypoglycemia. An aggressive approach to management of this disorder is required if permanent neurologic damage is to be minimized.

Surgical treatment of organic pancreatic hypoglycemia in the pediatric age

From 1974 to 1980, 6 patients were operated upon for organic hyperinsulinism. 218 patients reported in the last 5 years are studied. Age at onset of symptoms is the most important factor. In infants the diagnosis is urgent. A severe mental retardation can result from waste of time in diagnosis and treatment. Simultaneous measurement of blood glucose and insulinemia during fasting and feeding periods is sufficient. Diffuse lesions are frequent, even associated with Islet cell adenoma. Surgery based upon local portal insulinemia must be adequately large and should avoid repeated pancreatectomy. In older children the diagnosis is easy. When a localised lesion is the pathologic feature, after a complete exposure of the gland, local excision is the technique of choice.

Nesidiodysplasia and nesidioblastosis of infancy: structural and functional correlations with the syndrome of hyperinsulinemic hypoglycemia

Subtotal pancreatectomy specimens of seven infants with persistent hyperinsulinemic hypoglycemia were studied; all showed the characteristic light microscopic picture of nesidioblastosis. Specimens were studied by electron and conventional light microscopy and by light microscopic immunohistochemistry for insulin, glucagon, somatostatin, and HPP (human pancreatic polypeptide); double staining and quantitative methods were also used. Findings were compared with those in age-matched controls. In the hyperinsulinemic hypoglycemic infants, an increase in total endocrine cell volume was found; however, the typical features of nesidioblastosis were also found in the controls. In both groups, immunohistochemistry and electron microscopy suggested that some endocrine cells are capable of producing synchronously more than one hormone. Amphicrine ("composite" or "intermediate") cells with exocrine and endocrine differentiation were found in three hypoglycemic infants. Observations are discussed in relation to current concepts of embryogenesis of the gastroenteropancreative endocrine system. We conclude that nesidioblastosis, as defined anatomically cannot be considered as the morphologic basis of hyperinsulinemic hypoglycemia. The term "nesidiodysplasia" is suggested and includes increased, maldistributed, and malregulated or malprogrammed endocrine and amphicrine cells when associated with endocrine abnormality.

Effect of somatostatin infusion on intermediary metabolism and entero-insular hormone release in infants with hyperinsulinaemic hypoglycaemia

The hypoglycaemia of infantile hyperinsulinism is often exceedingly difficult to control. The use of somatostatin has been advocated recently in such infants because of its effect on inhibiting insulin release, but nothing is known of the wider effects of this potent hormone in the young child. Two infants presenting at 9 weeks and 5 days of age with severe hyperinsulinaemic hypoglycaemia were studied during an infusion of somatostatin. In both infants normoglycaemia was restored with suppression of insulin secretion. An increase in blood ketone bodies occurred, but no change was seen in blood pyruvate, lactate or alanine concentrations. The plasma concentrations of glucagon, cortisol, growth hormone, motilin, pancreatic polypeptide, gastric inhibitory of polypeptide, neurotensin, gastrin and vasoactive intestinal peptide decreased markedly during the somatostatin infusion. No consistent change occurred in plasma enteroglucagon or secretin values. We conclude that somatostatin effectively suppresses abnormal insulin secretion in infants, but it has profound effects on the release of nine other hormones. Further studies are needed to define the consequences of suppressing the release of these hormones before somatostatin can be used routinely in the management of infantile hyperinsulinism.