Which test is NOT indicated as an initial step until the primary cancer is identified?

Which test is NOT indicated as an initial step until the primary cancer is identified?

• A. PTHRP
• B. CMP
• C. CT CHEST/ABD/PelVIS
• D. CBC

Answer: (A)

When evaluating suspected cancer, the initial workup focuses on broad diagnostic and staging steps that can locate the primary tumor and assess organ function: a CBC checks for anemia or abnormal counts, a CMP evaluates kidney function and electrolyte status, and a CT scan of the chest, abdomen, and pelvis visualizes the cancer and its extent. Parathyroid hormone-related peptide (PTHrP) is not part of this general initial assessment. It is a more specific marker used to evaluate hypercalcemia that is suspected to be due to a malignancy or to characterize paraneoplastic hypercalcemia once a cancer is already identified or suspected. Because you don’t yet know the primary cancer, measuring PTHrP does not help in locating or confirming it. Therefore, PTHrP is not indicated as an initial step until the cancer is identified.

When evaluating suspected cancer, the initial workup focuses on broad diagnostic and staging steps that can locate the primary tumor and assess organ function: a CBC checks for anemia or abnormal counts, a CMP evaluates kidney function and electrolyte status, and a CT scan of the chest, abdomen, and pelvis visualizes the cancer and its extent. Parathyroid hormone-related peptide (PTHrP) is not part of this general initial assessment. It is a more specific marker used to evaluate hypercalcemia that is suspected to be due to a malignancy or to characterize paraneoplastic hypercalcemia once a cancer is already identified or suspected. Because you don’t yet know the primary cancer, measuring PTHrP does not help in locating or confirming it. Therefore, PTHrP is not indicated as an initial step until the cancer is identified.