The Question is from neet-zoology chemical-coordincation-and-integration endocrine-glands-and-hormones, and it was created by the author Mr. BALACHANDRA.N

Question

A patient presents with persistent hypercalcemia, despite normal parathyroid hormone levels. Further investigation reveals elevated levels of a peptide hormone produced by a malignancy. Which hormone is MOST likely responsible for this patient's hypercalcemia?

Mr. BALACHANDRA.N · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Hypercalcemia causes and hormonal regulation of calcium metabolism.
 **Related Topics**: Parathyroid hormone (PTH), parathyroid hormone-related protein (PTHrP), malignancy-associated hypercalcemia, calcitonin.
 **Prerequisites**: Understanding of calcium homeostasis and the roles of PTH and calcitonin.
## SOLUTION PATHWAY
**Given Information**:
  - Persistent hypercalcemia (high blood calcium levels).
  - Normal parathyroid hormone (PTH) levels.
  - Elevated levels of a peptide hormone produced by a malignancy.
**Method & Steps**:
 1. Identify the cause of hypercalcemia.
  Reasoning:  Hypercalcemia can result from overproduction of PTH, increased bone resorption, or decreased calcium excretion by the kidneys.  Since PTH levels are normal, the cause is likely something other than PTH overproduction.
 2. Consider the role of malignancy.
  Working:  Malignancies can produce various hormones, leading to paraneoplastic syndromes. One such hormone is PTHrP, which mimics the effects of PTH, leading to increased bone resorption and hypercalcemia.
 3. Determine the most likely hormone.
  Result:  Parathyroid hormone-related protein (PTHrP) is the most likely cause of hypercalcemia in this patient, given the elevated levels of a peptide hormone produced by a malignancy and normal PTH levels.
  Verification:  The clinical presentation aligns perfectly with PTHrP-induced hypercalcemia. 
 ## OPTION ANALYSIS
A :x: Calcitonin lowers blood calcium levels, so it is not responsible for hypercalcemia.
B ✓: Parathyroid hormone-related protein (PTHrP) mimics the effects of PTH, leading to increased bone resorption and hypercalcemia. This is consistent with the given information.
C :x: Thyroxine (T4) is a thyroid hormone and is not directly involved in calcium regulation.
D :x: Adrenocorticotropic hormone (ACTH) is involved in the stress response and cortisol production; it does not directly affect calcium levels.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the roles of PTH and calcitonin: Remember that PTH increases blood calcium, while calcitonin decreases it.
  2.Overlooking paraneoplastic syndromes:  Malignancies can produce various hormones, leading to unexpected clinical presentations.
 **Quick Tips**:
  1.When faced with hypercalcemia and normal PTH, consider PTHrP-producing malignancies.
  2.Remember the mnemonic “PTHrP for Paraneoplastic Hypercalcemia”.

Mr. BALACHANDRA.N · Answer

Calcitonin

Mr. BALACHANDRA.N · Answer

The correct Option is "Parathyroid hormone-related protein (PTHrP)"

Mr. BALACHANDRA.N · Answer

Thyroxine (T4)

Mr. BALACHANDRA.N · Answer

Adrenocorticotropic hormone (ACTH)

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