12375 Rhabdomyolysis As A Cause Of PTH-independent Hypocalcemia In A Child With Acute Influenza Infection

Abstract Disclosure: S. Bhattarai: None. K. Halpin: None. Introduction: Hypocalcemia is characterized by low blood calcium level. Normal range for calcium for ages 12- 19-year is 8.5-10.6 mg/dli . Severe hypocalcemia is considered as serum calcium level of <7 mg/dl. Hypoparathyroidism, pseudohypoparathyroidism and Vitamin D deficiency are some of the most common causes encountered by pediatrician endocrinologists. Rhabdomyolysis with hypocalcemia and elevated PTH is a rare presentation that should be considered, particularly for children presenting with acute viral illness. We present a rare case of rhabdomyolysis associated with hypocalcemia not related to hypoparathyroidism. Case: A 12-year-old female presented to the ED with body ache, poor oral intake and vomiting. She was found to be influenza positive. Labs showed hypocalcemia (4.8 mg/dl). She had an undetectable 25-OH vitamin D level (<5 ng/ml) and elevated iPTH level (609 pg/ml). We discussed the possibility of her etiology of hypocalcemia as Vitamin D deficiency although her presentation was atypical at an older age with negative imaging for rickets, hyperphosphatemia (6.0 mg/dl), and normal ALP (334 unit/L). She did not have any phenotypic features of Albright’s hereditary osteodystrophy with normal renal function. She had elevated CK (4829 U/L) supporting rhabdomyolysis secondary to acute influenza as a cause of her hypocalcemia. Rhabdomyolysis, a known complication of influenza infection, causes cell membrane destruction which impairs the normal function of Na-K-ATPase channel leading to increase in intracellular sodium activating Na/Ca exchanger. This in turn causes influx of calcium intracellularly causing hypocalcemia. Additionally, any injury leads to high phosphorus release from cells due to its lysis. High phosphorus is also caused by reduced oxidative metabolism in muscles impairing phosphate use. This excess of phosphate then combines with calcium and causes calcium-phosphate complex in soft tissues. Hyperphosphatemia additionally inhibits 1 alpha hydroxylase limiting formation of calcitriol leading to hypocalcemia. iiConclusion: Our patient had severe hypocalcemia due to influenza-related rhabdomyolysis. Rhabdomyolysis is an important cause of hypocalcemia in children, especially with acute viral illness. Accordingly, it is also important to obtain serum electrolytes in patients presenting with rhabdomyolysis as hypocalcemia may lead to complications like seizures and cardiac arrhythmia. Endnotes:i Roizen, Jeffrey & Shah, Vipul & Levine, Michael & Carlow, Dean. (2013). Determination of Reference Intervals for Serum Total Calcium in the Vitamin D-Replete Pediatric Population. The Journal of clinical endocrinology and metabolism. 98. 10.1210/jc.2013-3105.ii Ding LN, Wang Y, Tian J, Ye LF, Chen S, Wu SM, Shang WB. Primary hypoparathyroidism accompanied by rhabdomyolysis induced by infection: A case report. World J Clin Cases. 2019 Oct 6;7(19) Presentation: 6/2/2024