SAT-745 - Basal Ganglia Calcification: A Clue to Congenital Hypoparathyroidism

Background
Basal ganglia calcification (BGC) can serve as a diagnostic clue to underlying metabolic, infectious, or genetic disorders. Among these, congenital hypoparathyroidism represents a significant yet overlooked cause of BGC.
Case Presentations
Case 1: A 38-year-old male with a confirmed GATA3 pathogenic variant. First presented at age 2 years old with developmental delay and sensorineural hearing loss. Hypoparathyroidism was diagnosed at age 33 following admission with hypocalcemia and pericarditis. CT brain showed extensive bilateral BGC. He is treated with calcium and active vitamin D, and serum corrected calcium is maintained in the low normal reference range.
Case 2: A 14-year-old male presented with seizure in association with hypocalcemia and inappropriately normal PTH. Diagnosis of idiopathic hypoparathyroidism was made, and DNA analysis did not show pathogenic or likely pathogenic variant in gens associated with congenital hypoparathyroidism. He had normal adrenal and gonadal functions, no history of mucocutaneous candidiasis or other autoimmune disorders; magnesium was normal; medical history was noncontributory. He was treated with calcium, magnesium and active vitamin D and has not had any further seizures. CT brain at time of diagnosis showed bilateral BGC. Lab investigations showed low normal serum corrected calcium, low magnesium, and normal phosphate.
Case 3: A 16-year-old female with autosomal dominant hypocalcemia type1(ADH1). First presented to ER at the age of 17 months with grand mal seizures, low serum corrected calcium, and low PTH consistent with congenital hypoparathyroidism. At age 10-year-old DNA analysis confirmed the presence of a CASR pathogenic variant. At the age 12-years-old MRI brain was completed and showed bilateral BGC. She is treated with calcium and active vitamin D and magnesium; the serum corrected calcium is in the low normal reference range and phosphate is normal.
Case 4: A 17-year-old male with ADH1 and has a likely pathogenic variant in the CaSR gene. First diagnosed at age 5 years old with seizures and had hypocalcemia with low PTH, and high phosphate. CT brain showed multifocal calcifications involving the bilateral globi pallidi and subcortical white matter of the bilateral frontal lobes. He was initially treated with calcium and active vitamin D. However, calcium supplements were discontinued due to hypercalcemia and hypercalciuria. He is currently being treated with active vitamin D and dietary calcium.
Conclusions
BGC may represent an early radiologic marker of underlying congenital hypoparathyroidism. Early diagnosis and careful management of hypoparathyroidism, targeting serum ionized (or albumin-corrected) calcium in the low-normal range or just below the reference range and avoiding hyperphosphatemia, may limit progression of BGC.

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