Insulinomas are rare insulin-secreting tumors of pancreatic origin that cause hypoglycemia and can be associated with multiple endocrine neoplasia type 1 (MEN1). Whilst rare, they are the most common cause of hypoglycemia related to endogenous hyperinsulinism. A 28 year old woman with known MEN1 presented with postprandial hypoglycemia in second trimester of pregnancy. Prior to her presentation she was known to have several pancreatic neuroendocrine tumors which had been stable on serial imaging, but no history of hypoglycemia. She was managed with dietary intervention during pregnancy and gave birth to a healthy baby at 37 weeks gestation. After pregnancy, hypoglycemia initially resolved, but then recurred at 8 months postpartum. Magnetic resonance imaging showed several pancreatic neoplasms with the largest lesion measuring 29 mm in the pancreatic tail, unchanged from previous imaging. After localization with a selective arterial calcium stimulation test, she underwent successful distal pancreatectomy with resolution of symptoms. This case is unusual in that her initial presentation was during pregnancy, she had predominantly postprandial rather than fasting hypoglycemia and her symptoms remitted for several months after delivery. Key learning points are to have a low index of suspicion for an insulinoma when there is a history of MEN1 and the need for a pragmatic approach to diagnosis and treatment during pregnancy.
Introduction: While transient parathyroid insufficiency is not an uncommon complication of thyroidectomy, severe and prolonged hypocalcemia attributed to a combination of post-surgical hypoparathyroidism, hungry bone syndrome (HBS) and hypovitaminosis D is unusual. Clinical Case: A 17-year-old female from a remote community in Australia with Graves’ disease, complicated by exophthalmos and atrial flutter, underwent total thyroidectomy due to challenges with medication adherence leading to persistent thyrotoxicosis. FT4 was >150 pmol/L (normal 10–20 pmol/L) almost two years after diagnosis. Pre-operatively, she received Lugol’s iodine, carbimazole and beta-blockade. The operation was uncomplicated and three parathyroid glands were preserved. Within six hours of thyroidectomy, she developed symptomatic hypocalcemia with corrected calcium 1.9 mmol/L (7.6 mg/dL) (normal 2.2–2.65 mmol/L). PTH level was 0.8 pmol/L (normal 1.4–9.0 pmol/L). Magnesium and phosphate levels were initially normal but hyperphosphatemia developed the following day. 25-OH vitamin D was low (29 nmol/L, normal 50–150 nmol/L) and was corrected with high dose cholecalciferol. Despite use of continuous intravenous calcium gluconate in addition to oral calcium carbonate, as well as both intravenous and oral calcitriol and magnesium, urinary calcium excretion remained undetectable. Teriparatide 20 mcg BD was commenced on post-operative day 14 with no demonstrable improvement in serum calcium. Less than 48 hours after cessation of parenteral calcium on day 18 post-operation, corrected calcium and ionised calcium declined to 1.47 mmol/L (5.9 mg/dL) and 0.46 mmol/L (normal 1.15–1.33 mmol/L) respectively, prompting recommencement of calcium infusion. Her remarkably high requirement for calcium replacement with negligible urinary calcium excretion for at least one month in spite of parenteral calcium infusion for a total of three weeks’ duration is highly suggestive of HBS which became evident due to post-surgical hypoparathyroidism. She had elevated ALP (618 U/L, normal 35–140 U/L) and increased bone resorption marker (N-telopeptide/creatinine 262 nmol BCE/mmol, normal <100 nmol BCE/mmol), with osteopenia at lumbar spine (Z-score -1.7) and femur (Z-score -1.3). Additionally, vitamin D deficiency is likely to have contributed to the severity of hypocalcemia. 60 days after surgery, she was still requiring calcium carbonate 2500 mg QID (4 g/day elemental calcium) and calcitriol 1 mcg TDS. Her phosphate level had normalised and ALP gradually declined to 241 U/L. Clinical Lesson: This case highlights the importance of attaining euthyroid status as early as possible pre-operatively to allow near-complete reversal of thyrotoxicosis-induced osteodystrophy, as indicated by normalisation of serum ALP, and ensuring vitamin D levels are replete prior to thyroidectomy for Graves’ disease.
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