Intermittent hypoglycemia in a horse with anaplastic carcinoma of the kidney

Resolution of paraneoplastic hypoglycemia following nephroureterectomy for treatment of canine renal cell carcinoma: Case report

Objectives

To describe the clinicopathologic findings, imaging results, surgical treatment, and outcome of a dog with renal cell carcinoma (RCC) and paraneoplastic hypoglycemia.

Animals

A 13-year-old female spayed mixed breed dog that was presented for facial twitching and neurologic decline and diagnosed with a renal mass and paraneoplastic hypoglycemia.

Study design

Case report.

Methods

Serum chemistry revealed severe hypoglycemia and normal renal values. Abdominal ultrasonography showed a large, heterogeneous, cavitated mass associated with the left kidney and no evidence of abdominal metastatic disease. Thoracic radiographs revealed no evidence of pulmonary metastatic disease. Fasted serum insulin was low concurrently with severe hypoglycemia. No other causes of hypoglycemia were detected, and paraneoplastic hypoglycemia was suspected.

Results

After initial medical management of the dog's hypoglycemia, left nephroureterectomy was performed. Histopathology was consistent with RCC. Postoperatively, the dog's hypoglycemia resolved, and supplementation was discontinued. The dog remained stable and was discharged from the hospital 3 days after surgery. At 2-week, 3-month, and 5-month follow up evaluations, the dog remained euglycemic, and no definitive evidence of disease progression was detected. Eight months postoperatively, the dog was euthanized due to decline in mobility. Necropsy and histopathology revealed cerebral and spinal cord multifocal myelin sheath dilation and two primary pulmonary carcinomas with no evidence of recurrence or metastasis of the RCC.

Conclusion

Surgical treatment of RCC with subsequent resolution of paraneoplastic hypoglycemia has not previously been reported in veterinary medicine. In this dog, nephroureterectomy for RCC resulted in immediate and sustained resolution of paraneoplastic hypoglycemia.

Presumed Neuroglycopenia Caused by Severe Hypoglycemia in Horses

BACKGROUND

Neuroglycopenia refers to a shortage of glucose in the brain resulting in neuronal dysfunction and death if left untreated. Presumed neuroglycopenia has not been described in horses.

OBJECTIVE

To report neurological signs in horses with presumed neuroglycopenia as the result of severe hypoglycemia.

ANIMALS

Ninety horses (hours to 28 years of age) diagnosed with hypoglycemia (blood glucose concentration < 75 mg/dL [< 4.2 mmol/L]).

METHODS

Retrospective study. Electronic medical records were searched. Signalment, history, complaint, clinical signs, laboratory findings including CSF analysis, electroencephalogram, clinical or definitive diagnosis, and outcome were recorded. Kruskal-Wallis analysis of variance and logistic regression were used to investigate association between blood glucose concentration and data extracted. Statistical significance was set at P < 0.05.

RESULTS

Thirty-eight and 52 horses had mild (50-74 mg/dL [2.8-4.1 mmol/L]), and severe hypoglycemia (< 50 mg/dL [< 2.8 mmol/L]), respectively. Most common causes of hypoglycemia included liver and gastrointestinal (40%) disease, sepsis (33%), neoplasia (7%), and insulin-induced (4%). Most common neurologic deficits included obtundation (100%), seizures (42%), and disorientation (22%). CSF-glucose was severely low (mean 2.5 mg/dL [0.1 mmol/L], median 0 mg/dL). Paroxysmal discharges in support of seizures were identified in the occipital (visual) and parietal (closest to temporal-auditory) cortical regions upon EEG examination (8/8 horses).

CONCLUSIONS AND CLINICAL IMPORTANCE

Neuroglycopenia is presumed to occur in horses as the result of severe hypoglycemia. Subclinical seizures, and intermittent blindness and deafness of cortical origin can occur. Severe altered state of consciousness and seizures can be observed at a blood glucose cut-off value of < 42 mg/dL (< 2.3 mmol/L).

Tumors, IGF-2, and hypoglycemia: insights from the clinic, the laboratory, and the historical archive

Tumors of mesenchymal and epithelial origin produce IGF-2, which activates pathways in the tumors. In a minority of patients, the tumors (hepatomas, fibromas, and fibrosarcomas are the most common among many) release into the circulation enough IGF-2-related peptides to mimic the fasting hypoglycemia characteristic of patients with insulin-producing islet-cell tumors. Rarely, markedly elevated IGF-2 levels produce somatic changes suggestive of acromegaly. Typically, the elevated IGF-2 levels are associated with suppressed plasma levels of insulin, IGF-1, and GH. Complicating the pathophysiology are the IGF binding proteins (IGFBPs) that can bind IGF-2 and IGF-1, modifying hormone metabolism and action. IGFBP concentrations are often altered in the presence of these tumors. At the cellular level, the 3 hormone-related ligands, IGF-2, IGF-1, and insulin, all bind to 4 (or more) types of IGF-1 receptor (IGF-1R) and insulin receptor (IR). Each receptor has its own characteristic affinity for each ligand, a tyrosine kinase, and overlapping profiles of action in the target cells. The IGF-2R, in addition to binding mannose-6-phosphate-containing proteins, provides an IGF-2 degradation pathway. Recent evidence suggests IGF-2R involvement also in signal transduction. Surgery, the treatment of choice, can produce a cure. For patients not cured by surgery, multiple therapies exist, for the tumor and for hypoglycemia. Potential future therapeutic approaches are sketched. From 1910 to 1930, hypoglycemia, insulin, insulinomas, and non-islet-cell tumors were recognized. The latter third of the century witnessed the emergence of the immunoassay for insulin; the IGFs, their binding proteins, and assays to measure them; and receptors for the insulin-related peptides as well as the intracellular pathways beyond the receptor. In closing, we replace non-islet-cell tumor hypoglycemia, an outdated and misleading label, with IGF-2-oma, self-explanatory and consistent with names of other hormone-secreting tumors.

Gastrointestinal stromal tumour and hypoglycemia in a Fjord pony: case report

Background

Neoplasia may cause hypoglycemia in different species including the horse, but hypoglycemia has not previously been reported in the horse associated with gastrointestinal stromal tumours.

Case presentation

A case of a gastrointestinal stromal tumour in a Fjord pony with severe recurrent hypoglycemia is presented. The mechanism causing the hypoglycemia was not established.

Conclusion

This case indicates that a gastrointestinal stromal tumour may cause hypoglycemia also in the horse.