Profound hypercalcaemia secondary to immobilisation in a patient with complex cyanotic congenital heart disease

Haider Imtiaz; Low Bailey C; Margaret Lubczynska; Ali Aljumaah; Arjun Raj; Saraa Abdinor; Emma Bremner; Mary Barrowcliffe; Shailesh Gohil; Amy Morrison; Reddy Narendra L; Levy Miles J

doi:10.1530/endoabs.109.P84

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Endocrine Abstracts (2025) 109 P84 | DOI: 10.1530/endoabs.109.P84

SFEBES2025 Poster Presentations Bone and Calcium (25 abstracts)

Profound hypercalcaemia secondary to immobilisation in a patient with complex cyanotic congenital heart disease

Haider Imtiaz ¹ , Bailey C Low ² , Margaret Lubczynska ¹ , Ali Aljumaah ¹ , Arjun Raj ¹ , Saraa Abdinor ¹ , Emma Bremner ¹ , Mary Barrowcliffe ¹ , Shailesh Gohil ¹ , Amy Morrison ¹ , Narendra L Reddy ¹ & Miles J Levy ¹

Author affiliations

¹University Hospitals of Leicester, Leicester, United Kingdom; ²University of Leicester, Leicester, United Kingdom

Background: Profound hypercalcaemia secondary to immobilisation is an exceptionally rare condition, characterized by the efflux of calcium from bones due to increased osteoclastic activity. It necessitates careful evaluation to exclude more common causes such as primary hyperparathyroidism and malignancy.

Case Presentation: We present the case of a 21-year-old male with a history of complex cyanotic congenital heart disease, who was referred to the Endocrinology outpatient clinic from Cardiology due to an incidental finding of severe hypercalcaemia (corrected calcium level of 4.2 mmol/l). The patient had undergone a Fontan procedure, resulting in protein-losing enteropathy, a common complication associated with congenital heart disease. His phosphate levels were normal (0.88 mmol/l), and parathyroid hormone (PTH) levels were within the normal range (7.54 pmol/l). Bone-specific alkaline phosphatase levels were also normal, indicating impaired bone remodelling favouring osteoclastic activity. The patient, mostly wheelchair-bound, appeared cyanosed and cachectic upon examination.

Management and Outcome: Due to the complexity of his underlying conditions, the patient was promptly transferred to the congenital heart disease department for careful fluid resuscitation. He received approximately 2 litres of normal saline over 24 hours, followed by a pamidronate infusion. A CT scan of the chest, abdomen, and pelvis revealed progressive dysplastic liver nodules secondary to the Fontan procedure, with no evidence of malignancy. After 72 hours of fluid resuscitation, his corrected calcium levels decreased to 3.3 mmol/l. He was subsequently referred to the rehabilitation team for early mobilization to prevent recurrent hypercalcaemia.

Conclusion: This case highlights the rarity of immobilisation-induced hypercalcaemia outside of traumatic spinal cord injuries. It underscores the diagnostic challenges and the necessity for a multidisciplinary approach involving endocrinologists, rehabilitation specialists, and congenital heart disease experts. Bisphosphonates and Denosumab remain the cornerstone of management, inhibiting osteoclastic bone resorption, the primary etiological factor in immobilisation hypercalcaemia.