(4.10) Post-Operative Hypoparathyroidism requiring Initiation of Teriparatide in the Setting of Calcitriol Shortage

Thursday, May 9, 2024

12:25 PM – 12:40 PM CDT

Location: ePoster Showcase, Empire Ballroom Foyer, Level 2

Submitter(s)

Lidiya Kukova, MD (she/her/hers)

Resident
University of Maryland Medical Center

Introduction : Hypoparathyroidism is one of the few hormone deficiency disorders not managed with direct replacement of the missing hormone. Instead, calcium and vitamin D repletion are considered first line therapy. Use of synthetic parathyroid hormone (PTH) replacement is considered second line therapy for management of hypoparathyroidism and should only be utilized if a patient’s hypocalcemia is refractory to standard treatment. This case report demonstrates successful short-term use of teriparatide for management of hypoparathyroidism in the setting of a calcitriol shortage.

Case(s) Description : A male patient in his late 60s presented for surgical management of recurrent squamous cell carcinoma of the supraglottis about 18 months after initial treatment of the malignancy. The patient underwent a total laryngopharyngectomy with bilateral neck dissection and a right completion thyroidectomy. Following the surgery, he was found to have a PTH of < 4pg/mL with a corrected calcium (cCa) of 8.8mg/dL. and the patient was recommended to start calcium carbonate, cholecalciferol, and calcitriol. Due to the patient's surgery, he was only able to receive medications through a gastrostomy tube (g-tube) and so his calcitriol had to be given in either intravenous or liquid form. Around two weeks into the hospitalization, there was no longer availability of liquid or intravenous calcitriol due to a critical shortage of the medication because the only US supplier declared bankruptcy.
Consequently, after two days of missed calcitriol doses due to the medication shortage, the patient’s cCa decreased to 6.8mg/dL. He was therefore started on a calcium gluconate intravenous drip. During that time, the patient also started simultaneously receiving calcium carbonate 2600mg three times daily, ergocalciferol 1250mcg weekly, and hydrochlorothiazide 25mg daily. The calcium carbonate was eventually switched to calcium citrate 2000mg three times daily and the ergocalciferol was increased to 1250mcg daily. Despite these changes, the patient continued to require the calcium gluconate drip in order to maintain a cCa around 8mg/dL.

Given the continued intravenous calcium requirement, an alternative treatment modality with subcutaneous teriparatide 20mcg twice daily was attempted. One day after initiation of the teriparatide, the calcium gluconate drip was discontinued, and the patient was able to consistently maintain a cCa of 9-9.6mg/dL. The patient was discharged two days later on a home regimen consisting of teriparatide 20mcg twice daily, calcium citrate 2000mg three times daily and ergocalciferol 1250mcg (50,000 units) daily. Hydrochlorothiazide 25mg was discontinued at time of discharge.

Discussion :

This report exemplified a case of successful short-term use of teriparatide in the management of hypoparathyroidism. Based on the results of prior small-scale studies investigating the utility of teriparatide in the treatment of the condition, the medication warrants further investigation for use as a first-line agent for patients with hypoparathyroidism given the potential for improved morbidity.