A case report of reactive hypoglycemia in a patient with pheochromocytoma and it's review of literature

Phaeochromocytomas overexpress insulin transcript and produce insulin

INTRODUCTION

Phaeochromocytomas are tumours originating in the medulla of the adrenal gland. They produce catecholamines, and some tumours also produce ectopic hormones. Two types of glucose imbalances occur in phaeochromocytoma patients, hyperglycaemia and hypoglycaemic attacks. Therefore, we tested whether insulin transcript (INS), insulin, and a hybrid read-through transcript between exons from insulin and insulin-like growth factor 2 (INS-IGF2) were expressed in phaeochromocytomas.

METHODS

We measured the expression of insulin using immunohistochemistry. The expression of INS-IGF2 was determined by qRT-PCR in formalin-fixed and paraffin-embedded tissue from 20 phaeochromocytomas. The expression of INS and INS-IGF2 transcriptswas also analysed in 182 phaeochromocytomas and paragangliomas using publicly available datasets in The Cancer Genome Atlas (TCGA) Database.

RESULTS

Of 20 phaeochromocytomas, 16 stained positive for insulin. The distribution of positive cells was mostly scattered, with some focal expression indicating clonal expansion. Nineteen tumours expressed high levels of INS and INS-IGF2 transcripts. The expression of the two transcripts corresponded closely. In the TCGA dataset, phaeochromocytoma expresses higher levels of INS and INS-IGF2 transcripts compared to the normal non-tumour adrenal glands. Thus, the expression of INS and INS-IGF2 seems to be a general phenomenon in phaeochromocytoma.

CONCLUSION

Most phaeochromocytomas contain cells that overexpress INS and INS-IGF2 transcripts. Most tumours also display heterogeneous expression of polypeptides immunoreactive to monoclonal anti-insulin antibodies. Clinically this may relate to both hyperglycaemia and hypoglycaemic attacks seen in patients with phaeochromocytoma as well as autocrine tumour growth.

Hypoglycemia as a Symptom of Neoplastic Disease, with a focus on Insulin-like Growth Factors Producing Tumors

This article reviews the current knowledge of uncommon causes of hypoglycemia, with a focus on neoplastic disease. However, these situations are rare. They commonly accompany severely ill patients and therefore a proper diagnosis is the basis for relevant treatment. Here we discuss the pathophysiological foundation of hypoglycemia - situations caused by increased insulin production or sensitivity - but we also focus on different cytokines which could cause hypoglycemia, especially IGF-II production in what are called nonislet cell tumors. From the clinical perspective we can divide the patients who are affected into "seemingly ill” or “healthy patients” and lead the diagnostic process accordingly.

Cardiogenic shock triggered by phaeochromocytoma crisis after an oral glucose tolerance test: a case report

Background

Phaeochromocytomas are rare catecholamine-producing tumours which typically present with comparatively benign symptoms such as headache, palpitations, sweating, hypertension, and insulin resistance. In rare cases, severe cardiac manifestations have been reported. We describe a patient who developed severe hypoglycaemia after an oral glucose tolerance test (OGTT), potentially triggering a phaeochromocytoma crisis and cardiogenic shock. To the best of our knowledge, only four other cases of hypoglycaemia after OGTT have been reported in patients with phaeochromocytoma, of which none developed a phaeochromocytoma crisis.

Case summary

A 53-year-old woman with hypertension, dyslipidaemia, and prediabetes presented to the Emergency Department with hypoxia, hyperglycaemia, lactic acidosis, severe left ventricular dysfunction, and pulmonary oedema followed by cardiogenic shock. Onset of symptoms was only few hours after an OGTT during which she had developed severe transient hypoglycaemia. Angiography was performed due to elevated troponin levels and showed a midventricular contraction pattern typical of takotsubo. This was subsequently confirmed by cardiac magnetic resonance imaging. The patient’s condition improved during the first 36 h and she was discharged home on Day 7. A positive catecholamine test prompted readmission to the Endocrinology Unit, where computer tomography confirmed the diagnosis of phaeochromocytoma. An adrenalectomy was performed, and the diagnosis was verified histopathologically.

Discussion

The possibility of a phaeochromocytoma must be considered as a potential triggering factor in patients presenting with takotsubo cardiomyopathy, in particular, when blood glucose levels fluctuate between severe hypo- and hyperglycaemia.

Glycemic Disturbances in Pheochromocytoma and Paraganglioma

In this review article, we aimed to analyze the available data on pheochromocytomas and paragangliomas as it pertains to their not as well-recognized association with significant glycemic abnormalities in the preoperative, perioperative, and postoperative settings as well as how they should be managed clinically. Pheochromocytomas are rare adrenal tumors that account for about 0.1% of hypertension. Paragangliomas, on the other hand, are even less common and have fewer clinical manifestations. Both types of tumors may have unusual modes of presentation which can challenge even the most experienced clinicians and are easy to overlook, resulting in post-mortem diagnosis. We wish to draw further attention to the life-threatening effects on glucose and insulin homeostasis that can occur in the form of hyperglycemic and hypoglycemic states. Hyperglycemia is a result of a glucose intolerant state created in the setting of catecholamine excess, which can present in the form of resistant diabetes, diabetic ketoacidosis (DKA), or even hyperglycemic hyperosmolar states (HHS). In many reported cases, these abnormalities resolve with resection of the tumor. However, past clinicians have also described a state of "reactive hypoglycemia" that can occur following tumor resection, further emphasizing the need for very close perioperative and postoperative monitoring. Severe hypoglycemia may also occur with inherited diseases linked to pheochromocytoma such as von Hippel-Lindau (VHL) disease as well as predominantly epinephrine-producing tumors, given some of the dramatic downstream effects of alpha and beta adrenoceptor agonization. While much of the data remains anecdotal, clinicians will benefit from the awareness of the protean manifestations of these tumors and the varied and lesser-known effects on glucose and insulin homeostasis.