Endocrine Abstracts

Introduction: Hypercalcaemia is a frequent complication of breast cancer with bony metastasis. There is also an increase incidence of primary hyperparathyroidism among patients with breast cancer. We report a patient with breast cancer presenting with hypercalcaemia secondary to both parathyroid hormone- related peptide (PTHrP) from liver metastasis and possibly co-existing primary hyperparathyroidism.

Case report: A 53 year old woman, with a history of right sided breast cancer presented as an emergency due to general deterioration and was found to have hypercalcaemia. She had undergone mastectomy, completed six cycles of chemotherapy and 25 fraction of radiotherapy 10 months ago. Blood test revealed an adjusted calcium of 5.54 nmol/l (NR 2.10–2.55 nmol/l), PTHrP of > 60 pmol/l (NR 0.0–1.8 pmol/l), 25-OH Vitamin D of 12 nmol/l (NR 50–200 nmol/l), acute renal failure and deranged liver function tests. Further investigation included a bone scan which excluded any bony metastasis and an abdominal ultrasound revealing liver metastasis.

Despite appropriate treatment with intravenous fluid, bisphosphonate and steroid therapy, patient continued to deteriorate and died.

Conclusion: Hypercalcaemia in malignancy mostly results from bony metastasis and PTHrP. Recent data suggests a strong correlation between breast cancer and primary hyperparathyroidism. Although the exact pathogenesis is unclear, it has been attributed to be the possibility of common etiological pathways shared by the two conditions.

Our patient presented with extreme levels of hypercalcaemia, secondary to PTHrP associated with metastatic breast cancer, without bony involvement. Despite this high level of calcium level, PTH was still measurable, indicating probable primary hyperparathyroidism as well although it could also possibly be because of severe vitamin D deficiency and renal disease.

Hypercalcaemia secondary to PTHrP carries a poor prognosis and co-existing primary hyperparathyrodism in such setting can be an interesting observation but it does not dictate the course of the patients’ treatment or outcome.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.