Introduction: The IGF1 and 2 are polypeptides that share structural similarities to insulin and affect carbohydrate metabolism mainly by activating the IGF1 receptor. We report a patient presenting with prostate tumour and severe hypoglycaemia.
Case presentation: An 82-year-old male presented with frequent seizures and severe hypoglycaemia. Four year prior to the current presentation the patient had been diagnosed with prostate carcinoma, however, he refused surgical treatment. Our laboratory tests confirmed severe hypoglycaemia with low insulin levels at admission. Similarly, during fasting low glucose and low serum insulin levels were documented. Standard oral glucose load showed a diabetoid response, but the insulin response was delayed. An insulinoma could be excluded by various imaging techniques. Moreover, both glucagon and somatostatin tests showed negative results. Furthermore, physiological hypophysis and peripheral hormone concentrations, as well as normal IGF1 serum levels and chromogranin A were measured. Therefore, we hypothesised that the severe hypoglycaemia might have resulted from IGF2 (or its prohormone) synthesis by the previously diagnosed prostate tumour and thus a prostatectomy was recommended. The patient required continuous glucose substitution and diazoxide therapy under which the hypoglycaemia could be controlled, however, due to the poor general condition a surgical procedure was not feasible and the patient deceased. The subsequent immunohistochemistry of the prostate sections showed a carcinoma with strong IGF2 staining, further suggesting that the IGF2-secreting prostate tumour caused the severe hypoglycaemia.
Conclusions: To our knowledge, this is only the second reported case of an IGF2 secreting prostate tumour. It has been previously reported that some mesenchymal tumours secrete IGF2 at high levels causing severe, therapy refractory hypoglycaemia. Increased awareness of IGF2 may improve diagnosis and treatment of hypoglycaemias.