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What is A 68 year old male presented to the local general practitioner with complaints of low back ache which is more in the night. The pain was so severe that it interferes his sleep. During evaluation there was a bone lesion in the lumbar spine and biopsy from it is suggestive of blastic skeletal metastasis from an unknown primary. The next best blood test in this patient would be: and explain in detail?
In bone only metastases in men (blastic) check PSA and if elevated treat as prostatic cancer. Elevated serum PSA or tumor staining with PSA may provide confirmatory evidence of prostatic cancer in blastic bone metastasis. Ref: Harrisons Principles of Internal Medicine, 18th Edition, Pages 824-25