A 60-year-old male presents with fatigue and bone pain. His blood test shows a calcium level of 12 mg/dL, an albumin of 3.0 g/dL, and a PTH level of 10 pg/mL. What could be the potential causes, and what are the next steps?
This patient's presentation of bone pain and fatigue along with hypercalcemia and a low PTH level may suggest malignancy-related hypercalcemia, possibly due to a paraneoplastic syndrome or bony metastasis. Other causes of non-PTH mediated hypercalcemia, such as excessive vitamin D or calcium intake, should also be considered. The next steps should involve further investigation with imaging studies and possibly tumor markers to identify a potential malignancy.