Abstract #1165370: Unique Case of an Adult Patient with Neurofibromatosis Type 1 with Noonan Syndrome (NFNS) Features and Idiopathic Hypoparathyroidism Complicated by Recurrent Episodes of Hypo- and Hypercalcemia

Abstract

NFNS is a rare RASopathy consisting of phenotypic features of neurofibromatosis type I (NF-1) and Noonan syndrome (NS) features. Endocrine disorders in this syndrome can commonly involve growth hormone related disorders. Here, we present the management of an adult patient with a unique case of NFNS with idiopathic hypoparathyroidism. A 22-year-old male with NFNS diagnosed in early childhood presented to our facility. NF1-like features included multiple café-au-lait spots, Lisch nodules, and basal ganglia hamartomas. NS-like features included webbed neck, bilateral ptosis, low posteriorly set ears, short stature, and intellectual delay. Patient’s family history was significant for NF-1 in a brother and father, and a maternal grandmother with hypocalcemia throughout her childhood. Genetic testing was significant for a positive NF-1 gene panel and a negative NS gene panel, consistent with NFNS. It should be noted that at age 15, he presented with pre-B acute lymphoid lymphoma (ALL) and hypocalcemia. At the time, his ionized calcium level (iCa) was 0.57 mg/dL (n = 4.5-5.6 mg/dL) and total calcium was 4.2 mg/dL (n = 8.8-10.3 mg/dL). He had hyperphosphatemia of 9.2 mg/dL (n = 3.0-4.5 mg/dL) with a low PTH of 3.7 pg/mL (n = 10-65pg/mL) and hypomagnesemia of 1.4 mg/dL (n = 1.7-2.2 mg/dL). The patient was treated with calcitriol, calcium carbonate, vitamin D and magnesium gluconate. Since his hypoparathyroidism diagnosis, the patient has multiple readmissions for recurrent episodes of hypocalcemia and hypercalcemia. During his first hypercalcemic episode, the patient also had acute pancreatitis associated with a chemotherapy agent. He required treatment with aggressive fluids, subcutaneous calcitonin, furosemide, and termination of home calcium and calcitriol supplementation. Following these initial episodes, the patient has continued to have recurrent episodes of hypocalcemia and hypercalcemia that were not associated with any other etiology such as acute pancreatitis, chronic immobilization, or chemotherapy regimens. While there have been a few previous reports of hypoparathyroidism in NS [1, 2], none were noted in association with NFNS. In our extensive literature review, we have not been able to find another case report of idiopathic hypoparathyroidism in NFNS. We feel that the uniqueness of the case coupled with the challenges associated with the adulthood management of recurrent hypercalcemia and hypocalcemia in this patient makes this a very interesting case to present.