SAT-741 Rapid Resolution Of Transient Hypoparathyroidism Following Total Laryngectomy With Thyroidectomy: A Case Series And Review

Abstract Disclosure: A. Denha: None. M. Kashat: None. M. Brennan: None. Introduction: Extracellular calcium levels are tightly regulated by parathyroid hormone (PTH), vitamin D, and calcitonin, acting on bone, kidneys, and the GI tract. Hypoparathyroidism is characterized by hypocalcemia and hyperphosphatemia due to inadequate PTH secretion or action. Symptoms include muscle spasms, paresthesia, seizures, and in severe cases, arrhythmias and heart failure. The most common cause is iatrogenic damage during head and neck surgery. This report presents two cases of transient hypoparathyroidism following laryngectomy and thyroidectomy with rapid PTH normalization. Cases: A 63-year-old female with invasive laryngeal squamous cell carcinoma (SCC) underwent total laryngectomy and thyroidectomy following chemoradiation. Postoperative labs showed hypoparathyroidism (PTH <4 pg/mL) and hypocalcemia (corrected calcium 6.8 mg/dL). Pathology revealed a hyperplastic thyroid nodule and one hypercellular parathyroid gland. She was discharged on calcium carbonate 1500 mg and calcitriol 0.5 µg daily. Two weeks later, calcium improved (∼9 mg/dL) and PTH rose to 37 pg/mL; supplementation was discontinued, maintaining vitamin D. A 39-year-old male with moderately differentiated invasive laryngeal SCC underwent similar treatment. Labs showed PTH <4 pg/mL and calcium 7.1 mg/dL. No parathyroid tissue was identified. Hypocalcemia was deemed transient. Calcium, vitamin D, and calcitriol were initiated, with calcium normalizing (9.4 mg/dL) and doses tapered within two weeks. Discussion: Postsurgical hypoparathyroidism (PSHP) is transient, typically resolving within a few months following extensive neck surgery, with incidence ranging from 18-39%. Permanent PSHP, defined as persistent hypocalcemia with low PTH beyond 6 to 12 months, occurs in 1-7% of patients. Contributing factors include the number of preserved parathyroid glands, integrity of their blood supply, and preoperative vitamin D levels below 15 ng/mL. Clinical signs of hypocalcemia include neuromuscular excitability, such as paresthesia, muscle spasms, Chvostek and Trousseau signs, cognitive changes, and potentially fatal cardiac arrhythmias. Diagnosis requires assessment of albumin-corrected calcium, phosphorus, magnesium, and PTH levels. Management focuses on symptom control and maintaining calcium levels between 7.5-8.5 mg/dL while avoiding hypercalciuria to prevent renal complications. The cases presented demonstrate transient PSHP with faster-than-expected PTH recovery and decreasing supplementation needs. Presentation: Saturday, July 12, 2025