Endocrine Abstracts

Introduction: The most common causes of hypercalcemia are primary hyperparathyroidism and malignancy. Malignancy-related hypercalcemia occurs in approximately 20% - 30% of all cancer patients during their clinical course and mainly affects patients with solid tumors such as breast carcinoma.

Case Report : 57 yrs old woman was referred for hypercalcemia and osteoporosis. Laboratory: calcium 2.8 mmol/l (normal range 2.15 - 2.55) calculated ionized calcium 1.41 mmol/l (normal 0.9 – 1.3), PTH 8.2 pmol/l (normal 1.3 - 7.6), normal renal function, no symptoms of hypercalcemia. Osteoporosis was diagnosed in routine screening by decreased density in lumbar spine (0, 700 g/cm², T score – 3.2), no compressive fractures. She was managed with ibandronate 150 mg monthly and we continued with differential diagnosis of hypercalcemia. We found hypercalciuria: urine calcium 16.7 mmol/24 hours, urine calcium/creatinine 1.4 (normal 0.25-0.55), CCCR (calcium creatinine clearance ratio) 0, 04. Vitamin D supplementation was added to ibandronate. The ongoing laboratory monitoring is in the table. During the follow-up the patients was diagnosed with breast cancer. PTH was only slightly elevated and malignancy could be a possible cause of hypercalcemia in this case. She underwent oncological treatment: surgery 11/2020, chemotherapy 1-5/2021, radiotherapy 5-7/2021 and anti-oestrogen therapy from 5/2021. The final diagnosis: 30 mm invasive (no special type) breast carcinoma with one micrometastasis in one sentinel lymph node, no distant metastasis. Remission of the breast cancer has been documented after the treatment. The hypercalcemia persisted until we noticed the normalization of calcium levels during the last two visits to our clinic.

Conclusion : This case represents mild hypercalcemia in patient with osteoporosis and breast cancer. The diagnosis of osteoporosis and hypercalcemia was prior of the cancer diagnosis. Hypercalcemia of malignancy should be considered in cases without known malignancy. The calcium level normalised during more than 2 years after completed oncological treatment and documented remission. Bisphoshonates were indicated for osteoporosis and also probably helped maintain calcium levels. Supported by Ministry of Health Czech Republic - DRO (Institute of Endocrinology - EÚ, 00023761).