Endocrine Abstracts

Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome and is the second most common cause of tumor-related hypoglycemia following insulinoma. Its prevalence is not known and is likely that many cases would go undiagnosed. In here, we describe a patient with PNET who presented with severe hypoglycemia.

A 37-year-old male with known metastatic Pancreatic neuroendocrine tumors (PNET) presented with weight loss, sweating, and tremor, episodic altered sensorium. He had documented blood glucose values below 35 mg/dl during those episodes. He received two cycles of lutetium therapy and was referred to our institute. At blood glucose of 33 mg/dl, he had undetectable plasma insulin (≤0.19 mU/l), low C-peptide 0.159 ng/ml (normal: 0.8–4), cortisol: 5.6 μg/dl (n:5–29), GH: <0.05 ng/ml and low IGF1 <25 ng/ml (normal: 109–284 ng/ml). ACTH: 60 pg/ml (normal: 0–46), Na: 136 mmol/l (normal: 132–146), K: 4.2 mmol/l (normal:3.5–5.5), TSH 1.274 uIU/ml (n: 0.35–4.94), FT₄: 1.47 ng/dl (n:0.7–1.48), FT₃: 2.6 pg/ml (n: 1.71–3.81), prolactin: 8.28 ng/ml (n:2.1–17.7), LH: 5.08 IU/l (1.5–9.3), FSH: 10.22 IU/l (n:1.4–18.1), testosterone: 405.78 ng/dl (n:241–2270). Magnetic resonance imaging of pituitary gland was normal. We were started prednisolone 30 mg/day with which his symptoms abated. After prednisolone treatment, there was no recurrence of hypoglycemia on follow-up.

In NICTH patients, the serum levels of insulin, C-peptide, and IGF1 are usually decreased or undetectable; however, the circulating level of total IGF2 as determined by conventional immunometric or receptor assays may be increased, decreased, or normal. In the absence of IGF2 assays, low serum insulin in combination with low IGF1 levels at the time of hypoglycemia is a strong biochemical evidence of NICTH. High-dose glucocorticoid therapy has immediate beneficial effect on symptomatic hypoglycemia.