Introduction: Malignancies and hyperparathyroidism account for over 90% of cases of hypercalcaemia. When presenting with suppressed PTH, malignancy is its commonest cause. We present a case of PTH-independent hypercalcaemia of immobilisation responding to bisphosphonate therapy.
Case summary: A 57-year-old Caucasian male presented with significant weight loss and severe back pain. He consumed 50 units of alcohol a week, had stopped smoking 20 years earlier and was on no medication. He was found to be hypercalcaemic (Adjusted Ca 3.01 mmol/l (2.22.6)) with suppressed PTH and elevated Alkaline phosphatise, 443 u/l (50200), and ESR 74 mm/h (520). Nuclear medicine bone scan was reported as consistent with multiple skeletal metastasis.
With a presumed diagnosis of metastatic malignancy, he underwent further investigations. Myeloma screen was negative. PSA was elevated (6.2 ug/l (04)) and prostatic biopsies were benign. ACE and vitamin D3 were normal. CT of thorax and abdomen as well as upper and lower gastrointestinal endoscopies and brochoscopy were normal.
An MRI scan of his spine showed multiple vertebral fractures and features consistent with osteoporosis. A bone biopsy subsequently showed normal bone marrow with no evidence of malignancy. In the interim he received intravenous bisphosphonates and his calcium normalised. A DEXA scan showed a T score of 1.4 at spine and −1.1 at the hip. He was since commenced on oral bisphosphonates. His calcium and ALP remain normal at one-year follow-up. His ESR has normalised and his weight has increased.
Discussion: Our patients symptoms and bone scan were highly suspicious for malignancy although we have subsequently diagnosed multiple vertebral fractures due to osteoporosis and the resultant immobilisation is likely to have caused hypercalcaemia. Alcohol excess is a common cause of osteoporosis and osteopenia in men. Single doses of bisphosphonates have been shown to resolve immobilisation hypercalacemia in patients with spinal injury as it has done in our case.