Patients may experience fatigue, mental status changes, dehydration, or symptoms of nephrolithiasis in humoral hypercalcemia of malignancy , is when the serum calcium level is more than:
**Core Concept**
Humoral hypercalcemia of malignancy is a paraneoplastic syndrome caused by the production of parathyroid hormone-related protein (PTHrP) or other substances by cancer cells. This leads to increased serum calcium levels, which can cause a range of symptoms including fatigue, mental status changes, dehydration, and nephrolithiasis.
**Why the Correct Answer is Right**
The correct answer is 14 mg/dL. Elevated serum calcium levels in humoral hypercalcemia of malignancy are due to the increased production of PTHrP, which mimics the action of parathyroid hormone (PTH). PTHrP stimulates the release of calcium from bone, increases renal reabsorption of calcium, and decreases renal excretion of calcium. This leads to hypercalcemia, which can cause symptoms such as fatigue, mental status changes, dehydration, and nephrolithiasis.
**Why Each Wrong Option is Incorrect**
* **Option A:** This value is too low to cause significant hypercalcemia.
* **Option B:** This value is still within the normal range, and hypercalcemia is typically defined as a serum calcium level above 10.5 mg/dL.
* **Option D:** This value is too high, and hypercalcemia can cause significant symptoms and complications at levels above 15 mg/dL.
**Clinical Pearl / High-Yield Fact**
In humoral hypercalcemia of malignancy, the serum calcium level can fluctuate rapidly, and patients may present with severe symptoms at any time. A high index of suspicion is necessary to diagnose this condition, and treatment should be initiated promptly to prevent complications.
**Correct Answer:** C. 14 mg/dL