In a patient with elevated calcium and normal parathyroid hormone, which condition is most likely?

In a patient with elevated calcium and normal parathyroid hormone, which condition is most likely?

• A. Parathyroid hyperplasia
• B. Metastatic carcinoma
• C. Parathyroid adenoma
• D. Primary hyperthyroidism

Answer: (B)

Elevated calcium with a normal PTH points to PTH-independent hypercalcemia. In this scenario, malignancy is the most likely cause because cancers can raise calcium through bone destruction or by secreting PTH-related peptide (PTHrP), which increases calcium without elevating PTH. Parathyroid hyperplasia or adenoma would raise PTH and hence calcium via PTH, which doesn’t fit a normal PTH level. Primary hyperthyroidism can cause some hypercalcemia but does not typically present with this clear PTH-independent pattern. Therefore, metastatic carcinoma best explains the finding.

Elevated calcium with a normal PTH points to PTH-independent hypercalcemia. In this scenario, malignancy is the most likely cause because cancers can raise calcium through bone destruction or by secreting PTH-related peptide (PTHrP), which increases calcium without elevating PTH. Parathyroid hyperplasia or adenoma would raise PTH and hence calcium via PTH, which doesn’t fit a normal PTH level. Primary hyperthyroidism can cause some hypercalcemia but does not typically present with this clear PTH-independent pattern. Therefore, metastatic carcinoma best explains the finding.