Elderly man with known squamous cell carcinoma who presents with elevated calcium and otherwise normal labs, most consistent with PTHrP production
Key idea: Squamous cell carcinoma, breast cancer, renal cell carcinoma, ovarian cancer and bladder cancer are known for producing PTH-related peptide, which has the same effects as PTH (increased calcium, decreased phosphate)
Key idea: If answer was metastases to bone (commonly seen in breast cancer, multiple myeloma, prostate cancer) then patient would have back pain and/or imaging with osteolytic changes
Key idea: Lymphoma leads to hypercalcemia by leading to increased vitamin D levels
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