Studies of tumor hypoglycemia

Hypoglycemia, an atypical early sign of hepatocellular carcinoma

BACKGROUND

Hypoglycemia is extremely uncommon as the first presentation of hepatocellular carcinoma, and it occurs predominantly as a paraneoplastic manifestation.

METHODS

We report a case of a 38-year-old-man positive for hepatitis B surface antigen with high-serum viremia who presented with symptoms of acute severe hypoglycemia.

RESULTS

Laboratory tests confirmed hypoglycemia (serum glucose 1.54 mmol/L) with undetectable serum-C peptide (<0.5 µIU/mL) and slightly increased serum insulin concentration (35 µIU/mL). Alpha-fetoprotein serum level was 75,625 ng/mL. Abdominal ultrasonography and computed tomography revealed a big vascularized mass of 13 cm in diameter occupying most of the right lobe of the liver and an (18)F-fluoro-2-deoxy-D-glucose positron-emission tomography revealed a predominant uptake of glucose by the tumor mass.

CONCLUSIONS

These findings indicate that hepatocellular carcinoma-associated hypoglycemia may be due exclusively to increased glucose utilization by the tumor mass.

Intermittent hypoglycemia in a horse with anaplastic carcinoma of the kidney

Clinically apparent hypoglycemia is rare in adult horses. Hypoglycemia is a well-recognized paraneoplastic syndrome in humans and dogs with non-insulin-secreting tumors and may occur in horses as well. Hypoglycemia associated with non-insulin-secreting tumors is believed to result from production of an abnormal form of insulin-like growth factor II. Neoplasia should be considered in the differential diagnosis for adult horses with hypoglycemia.

Glucose utilization in a patient with hepatoma and hypoglycemia. Assessment by a positron emission tomography

Tumor glucose use in patients with non-islet-cell tumors has been difficult to measure, particularly in hepatoma, because of hepatic involvement by neoplasm. We studied a patient with nonhepatic recurrence of hepatoma after successful liver transplantation. Tumor tissue contained messenger RNA for insulin-like growth factor-II (IGF-II), and circulating high molecular weight components and E-peptide of IGF-II were increased. Glucose use measured by isotope dilution with [3-3H]glucose was 7.94 mg/kg fat-free mass per min, and splanchnic glucose production was 0.93 mg/kg fat-free mass per min. Glucose uptake and glucose model parameters were independently measured in tissues by positron emission tomography with 18F-fluoro-2-deoxy-D-glucose. Glucose uptake by heart muscle, liver, skeletal muscle, and neoplasm accounted for 0.8, 14, 44, and 15% of total glucose use, respectively. Model parameters in liver and neoplasm were not significantly different, and glucose transport and phosphorylation were twofold and fourfold greater than in muscle. This suggests that circulating IGF-II-like proteins are partial insulin agonists, and that hypoglycemia in hepatoma with IGF-II production is predominantly due to glucose uptake by skeletal muscle and suppression of glucose production.

Insulin-cancer relationships: possible dietary implication

Insulin is a major anabolic hormone in mammals and its involvement in malignancies is well documented. An attempt is made to classify experimental and human cancers into four groups, according to the way the tumors are affected by, or interact with, insulin. Such an approach provides a better understanding of the dietary effects on tumorigenesis. Since human cancers are of the insulin-producing/secreting or insulin-dependent types, it is suggested that screening of individuals for blood insulin level and reducing the insulin status by dietary means may lead to a decreased risk of cancer. Anti-insulin drugs may be useful as supplements to therapeutic treatment.

Case report: increased insulin sensitivity in tumor hypoglycemia in a diabetic patient: glucose metabolism in tumor hypoglycemia

A 58-year-old man, with primary hemochromatosis, cirrhosis, and diabetes mellitus treated with insulin developed hepatoma. As the tumor grew, he lost his dependence on insulin therapy and experienced episodes of hypoglycemia. His response to infuse insulin was studied using the euglycemic clamp technique. Insulin was infused at rates of 1 and 10 mu/kg/min. The insulin dose response curve was shifted to the left and at plasma insulin levels of 72 microU/ml, steady-state glucose consumption was 9.6 mg/kg/min, 50% more than in normals, and nearly three times greater than that in other cirrhotics. The insulin clearance rate was 4417 m1/m2/min, almost five and six times more than in normals and cirrhotics, respectively. Basal hepatic glucose production was 3.6 mg/kg/min, two and three times higher than in normal and in cirrhotic subjects, respectively. The decrease in amino acid during hyperinsulinemia was more than 30% higher than in normal and other cirrhotics. IFG-I and II levels were not elevated in this patient. Increased insulin sensitivity and increased insulin clearance and serum amino acid decrease in response to insulin in vivo, suggest that insulin responsive tissues are at last partially responsible for tumor hypoglycemia. The increased glucose disposal rate probably accounted for the disappearance of the diabetes.

Inappropriately elevated plasma insulin-like growth factor II in relation to suppressed insulin-like growth factor I in the diagnosis of non-islet cell tumour hypoglycaemia

The diagnosis of non-islet cell tumour (hypoinsulinaemic) hypoglycamia has been complicated by contradictory biochemical evidence. Although insulin-like growth factor II (IGF-II) has been identified as the hypoglycaemic agent, plasma levels are often not elevated. In this study specific radioimmunoassay procedures for the measurement of IGF-I and IGF-II are described. Reference data on plasma IGF-II concentrations in relation to a wide range of IGF-I levels have been accumulated using plasma samples from acromegalic, hypopituitary and insulinoma (i.e. hyperinsulinaemic hypoglycaemia) patients as well as normal subjects from all age groups. The reference data indicate that a low plasma IGF-I value is normally associated with a relatively low plasma IGF-II level. Within a group of hypoinsulinaemic hypoglycaemia patients, a small number, invariably with evidence of a neoplasm, had low plasma IGF-I concentrations but apparently normal IGF-II levels. We propose that, in such cases, an apparently normal plasma IGF-II value is inappropriately high for the low plasma IGF-I level and, in association with non-ketotic hypoinsulinaemia and suppressed plasma growth hormone (GH), is diagnostic of a non-islet cell tumour as the cause of hypoglycaemia.

Insulin-tumour interrelationship in EL4 lymphoma or thymoma-bearing mice. I. Alloxan-diabetic or non-diabetic mice

A study has been carried out in which a comparison was made between EL4 lymphoma (assumed to be an insulin-producing secreting tumour) and thymoma (an insulin-dependent tumour). Tumour development and incidence, 3H-thymidine incorporation and insulin content in tumours, the host's food intake, blood insulin, glucose and cholesterol were determined in non-diabetic and alloxan-diabetic mice. Whereas no significant differences were observed between the diabetic and non-diabetic EL4 tumour-bearing mice, the diabetic, thymoma tumour-bearing mice showed reduced tumour growth and lower tumour incidence as compared with their non-diabetic counterparts. Insulin administration to diabetic tumour bearing mice, enhanced 3H-thymidine incorporation in the thymoma tumour cells only, and the insulin content of the EL4 tumours was found to be higher than that of the thymoma tumours. Rapid diabetes remission was observed in the diabetic, EL4 tumour-bearing mice as compared with the thymoma tumour-bearing mice.

Tumor-induced hypoglycemia: a result of ectopic insulin production

A 73-year-old woman with a pelvic tumor of nerve cell origin who presented with recurrent episodes of hypoglycemia was demonstrated to have inappropriately elevated plasma insulin and hypoglycemia. The tumor contained Insulin (RIA), proinsulin and secretory type of granules. Removal of the tumor promptly produced hyperglycemia. Also no islet cell tumor was found in the pancreas, suggesting the tumor as the site of ectopic insulin production.

Different endocrinological properties, growth rate and sensitivity to chemotherapy of aplastic mammary carcinoma in normo- and hypoglycemic phase of tumor growth

An aplastic mammary carcinoma (AMC) grew slower in hypoglycemic mice (caused by fasting or by daily insulin injections) and in hyperglycemic mice (caused by alloxan or streptozotocin, or by daily injections of glucose) than in normoglycemic mice. The tumor was able to adapt to the unfavourable conditions of the diabetes; cells, when transplanted from diabetic donors into diabetic recipients, secreted immunoreactive insulin (IRI) and immunoreactive glucagon (IRG), which are deficient in the diabetic hosts. In the terminal (hypoglycemic) phase of tumor growth, the concentrations of glucose, IRI and IRG decreased. The immunological reactivity of the host animals was reduced in the hypoglycemic terminal phase. The tumor cells taken from hosts in this phase behaved differently from the cells taken in the normoglycemic phase. The "hypoglycemic" cells grew more slowly in healthy mice; the intensity of their DNA synthesis was diminished, their response to antitumor therapy was weaker. Furthermore, it was necessary to transplant more of these cells to obtain tumors in all recipients, and they lost their ability to adapt to diabetic conditions (i.e. secreted neither IRI nor IRG). Hypoglycemia was apparently the immediate cause of death in mice with AMC. Injections of glucose or glucagon into mice with AMC eliminated the hypoglycemia temporarily and postponed the death by 4 days. Mice treated with glucagon and with chemotherapy or immunotherapy survived 6-9 days longer than mice treated with chemo- or immunotherapy alone. Some of these differences between the end-stage and the progressively growing tumors could be explained in terms of tumor cell kinetics but some could be attributed to metabolic conditions of the host caused in part by the tumor.

Hypoglycemia associated with a leiomyosarcoma of the small bowel

A patient with recurrent hypoglycemic episodes associated with a leiomyosarcoma of the small bowel is described. Fasting plasma insulin levels were consistently low and a subnormal insulin response to provocative stimuli (oral glucose and i.v. glucagon) was shown. After removal of the tumor, hypoglycemic episodes disappeared, fasting plasma insulin concentrations rose to normal values and insulin response to both OGTT and glucagon test was markedly enhanced. The possible mechanisms responsible for the hypoglycemia and the causes of subnormal insulin response to provocative stimuli are discussed.

Habituation of a mammary aplastic carcinoma on diabetic conditions

Hypoglycemia and hypoinsulinemia accompanied the i.m. growth of mammary aplastic carcinoma in CBA mice. In hosts rendered diabetic by means of alloxan, the tumor decreased blood glucose levels to almost the level seen in non-diabetic mice. Tumors maintained in diabetic mice grew faster after each subsequent transplantation into diabetic mice, and we noted increased incorporation of 3H-thymidine into DNA of these tumor cells. The observed proliferation enhancement of mammary aplastic carcinoma maintained in diabetic mice is caused by de novo insulin and glucagon synthesis, apparently by the tumor cells themselves.

Fatal hypoglycemia after cytotoxic chemotherapy: a report of two cases and a review of the literature

Two cases, one of leukemia and one of a trophoblastic testicular teratoma, are described in which hypoglycemia occurred as a terminal event. The rarity of this association with these types of malignancy, together with possible mechanism, is discussed in a brief review of the literature.

Mesenchymal tumors associated with hypoglycemia: case report and review of the literature

Hypoglycemia secondary to malignant tumors is rare. Mesenchymal tumors of nonpancreatic origin are the most common tumors associated with the hypoglycemia syndrome, and the clinical features of 115 reported cases are reviewed. The major anatomic distributions of the tumors are thoracic (30%) abdominal (65%), and uncommon locations (less than 5%). Approximately 50% of the tumors were resectable (59 patients), and in 60% the surgical procedure was curative. In the remaining 40% local recurrence predominated related to site of tumor and presence of contiguous organ invasion. The application of multimodality adjuvant therapy for hypoglycemia associated mesenchymal tumors should be based on an understanding of the natural history of the tumor.

Adenocarcinoma of the pancreas associated with hypoglycemia: case report and review of the literature

The occurrence of profound hypoglycemia in a patient with metastatic adenocarcinoma of the pancreas is reported. In contrast to the four previously reported cases, no suggestion of excess insulin production was found. Metabolic studies in this patient suggest both increased peripheral glucose utilization and decreased hepatic glucose production as contributing factors which promoted the hypoglycemia.

Ectopic insulin and Occam's razor: reappraisal of the riddle of tumour hypoglycaemia

The concept of ectopic insulin production is challenged on the basis of a review of 120 cases from the literature on extrapancreatic tumours associated with hypoglycaemia in which insulin or insulin-like activity were measured. No case met two or more of five criteria of ectopic hormone production. The evidence indicates that hypoglycaemia of extrapancreatic tumours cannot be attributed to insulin. In those rare cases in which plasma insulin was reported as high, pancreatic beta-cells could not be excluded as the source of insulin. Interestingly, many of these dubious cases had carcinoid histology. The review also points out a close association between some spindle-cell tumours and carcinoid tumours which may be relevant to discussion on the disputed origin of some "mesothelial" tumours. Nonsuppressible insulin-like activity (NSILA) consists of a number of factors mimicking insulin activity which compete with insulin or proinsulin for membrane receptors and may crossreact in bioassays, immunoassays, and receptor assays. The question of whether one or several of these substances may be responsible for extrapancreatic hypoglycaemia remains to be elucidated.

Serum somatomedin and insulin levels in tumor hypoglycemia

Serum concentrations of somatomedin and immunoreactive insulin were measured during the hypoglycemic phase of 3 patients with tumor hypoglycemia. Normal amounts of somatomedin were detected in their fasting sera, but they may have been inappropriate (or associated with enhanced insulin-like activity) considering the degree of hypoglycemia. Fasting serum insulin levels were consistently depressed, and in two of the cases remained low even after an oral glucose load. Nevertheless, the blood glucose concentrations of these two patients fell to hypoglycemic levels again by 3 hours; the mechanism of this reactive hypoglycemia remains unclear.

Hypoglycaemia associated with an intrathoracic fibrosarcoma

A patient with an intrathoracic fibrosarcoma in whom disabling hypoglycaemic episodes occurred is reported. No further hypoglycaemic episodes occurred following removal of the tumour. The mechanism of the hypoglycaemia associated with non-pancreatic tumours is discussed. It seems that inadequate hepatic glucose output was an important factor in contributing to the hypoglycaemia in this patient.

Mechanisms of seizures and coma in hypoglycemia. Evidence for a direct effect of insulin on electrolyte transport in brain

The mechanisms involved in the production of hypoglycemic coma were studied in rabbits. Measurements were made in brain, cerebrospinal fluid (CSF), and plasma of osmolality, Na(+), K(+), Cl(-), water content, exogenous insulin, glucose, lactate, and glutamate, while pH, Pco(2), Po(2), and bicarbonate were evaluated in arterial blood, 35 min after i.v. injection of insulin (50 U/kg), plasma glucose did not change, but brain K(+) content increased significantly. Grand mal seizures were observed in unanesthetized animals (+/-SD) 133+/-37 min after administration of insulin, at a time when brain glucose was normal, but brain tissue content of Na(+), K(+), osmoles, and water was significantly greater than normal. Coma supervened 212+/-54 min after insulin injection, at which time brain glucose, lactate, and glutamate were significantly decreased. At both 35 and 146 min after insulin administration, exogenous insulin was present in brain, but not in the CSF. After 208 min of insulin administration, animals were given i.v. glucose and sacrificed 35 min later. Most changes in the brain produced by hypoglycemia were reversed by the administration of glucose. Hypoxia (Po(2) = 23 mm Hg) was produced and maintained for 35 min in another group of animals. Hypoxia caused brain edema but did not affect brain electrolyte content. However, brain lactate concentration was significantly greater than normal. The data indicate that the seizures noted early in the course of insulin-induced hypoglycemia are temporally related to a rise in brain osmolality secondary to an increased net transport into brain of Na(+) and K(+), probably caused by insulin, per se. As hypoglycemia persists, there is also depletion of energy-supplying substrates (glucose, lactate, glutamate) in the brain, an event which coincides with the onset of coma. The brain edema observed during hypoxia is largely due to an increase in brain osmolality secondary to accumulation of lactate.