From the Guidelines
The correct answer is C. Hypercalcemia, as it is the most common electrolyte abnormality associated with malignancy, particularly in lung cancer patients, occurring in approximately 10-25% of patients with lung cancer 1.
Key Points
- Hypercalcemia of malignancy is characterized by a suppressed intact parathyroid hormone (iPTH) level and a low or normal calcitriol level 1.
- The symptoms described in the case, such as confusion and constipation, are classic manifestations of hypercalcemia, which can also include nausea, vomiting, polyuria, polydipsia, and in severe cases, mental status changes, bradycardia, and hypotension 1.
- The diagnostic evaluation includes measuring serum concentrations of iPTH, PTHrP, 1,25-dihydroxyvitamin D, 25-hydroxyvitamin D, calcium, albumin, magnesium, and phosphorus 1.
- Treatment typically involves hydration, bisphosphonates, loop diuretics, and addressing the underlying malignancy, with additional therapeutic options such as glucocorticoids, gallium nitrate, and salmon calcitonin considered in certain cases 1.
Management Considerations
- Oral hydration may be effective in mild hypercalcemia, while moderate to severe hypercalcemia requires rehydrating with IV crystalloid fluids not containing calcium and giving loop diuretics as needed after correction of intravascular volume 1.
- Bisphosphonates, such as clodronate, pamidronate, and zoledronic acid, are usually effective in managing hypercalcemia of malignancy 1.
From the Research
Electrolyte Abnormalities in Malignancy
The question asks about the most common electrolyte abnormality associated with malignancy, particularly in the context of a 60-year-old male with a working diagnosis of lung cancer. The patient develops confusion and constipation, with laboratory results confirming an electrolyte imbalance.
Relevant Electrolyte Abnormalities
- Hypercalcemia: This is the most commonly associated electrolyte abnormality with malignancy, particularly in lung cancer patients 2, 3, 4.
- Hyponatremia: Although hyponatremia can occur in cancer patients, it is not as directly associated with malignancy as hypercalcemia 5, 6.
- Hypokalemia: This electrolyte abnormality can occur in cancer patients but is not the most common abnormality associated with malignancy 5, 6.
- Hypomagnesemia: While hypomagnesemia can occur in cancer patients, hypercalcemia is more directly linked to malignancy, especially in lung cancer 2, 3, 4.
Studies Supporting Hypercalcemia
Studies have shown that hypercalcemia is a common electrolyte abnormality in lung cancer patients, often caused by parathyroid hormone-related protein (PTHrP) 2, 3, 4. The presence of hypercalcemia in lung cancer patients can indicate a poor prognosis 2.
Conclusion Not Provided as per Request
However the answer to the question is
Answer
C. Hypercalcemia