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

Question

A patient presents with persistent hyponatremia, despite adequate fluid intake.  Further investigation reveals inappropriately high urine osmolality. Which pituitary hormone deficiency is MOST likely responsible for this condition?

Mr. BALACHANDRA.N · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Endocrine regulation of water balance
 **Related Topics**: Pituitary hormones, Hyponatremia, Urine osmolality, Vasopressin (ADH) function
 **Prerequisites**: Understanding of fluid balance, hormone function, and electrolyte homeostasis.
## SOLUTION PATHWAY
**Given Information**:
  * Persistent hyponatremia (low sodium in blood)
  * Adequate fluid intake
  * Inappropriately high urine osmolality (concentrated urine)
**Method & Steps**:
 1. Analyze the symptoms: Hyponatremia indicates low sodium levels in the blood.  Normally, the kidneys would excrete more dilute urine to compensate. However, the high urine osmolality suggests the kidneys are retaining water.
  Reasoning:  This paradox—low sodium with concentrated urine—points to a problem with water excretion.
  Formula/Rule: No specific formula, this is a clinical interpretation.
 2. Consider the role of vasopressin (ADH): Vasopressin (Antidiuretic Hormone) is crucial for regulating water reabsorption in the kidneys.  It increases water permeability in the collecting ducts, leading to more concentrated urine and decreased water excretion.
  Working: A deficiency in vasopressin would prevent the kidneys from concentrating urine appropriately.  Despite adequate fluid intake, the body would still retain water, diluting the sodium concentration in the blood and causing hyponatremia.
  Key Point:  The inappropriately high urine osmolality is a key indicator of ADH deficiency.  The kidneys are trying to conserve water, but they shouldn't be concentrating urine this much given the adequate fluid intake.
 3. Evaluate other options: Oxytocin, growth hormone, and prolactin are not directly involved in the regulation of water balance in this context.
  Result: Vasopressin (ADH) deficiency is the most likely cause.
  Verification: The symptoms (hyponatremia, high urine osmolality despite adequate fluid intake) align perfectly with the known effects of ADH deficiency (diabetes insipidus).
 ## OPTION ANALYSIS
A ✓: Vasopressin (ADH) deficiency leads to the inability to concentrate urine, resulting in excessive water loss and hyponatremia even with adequate fluid intake. The high urine osmolality is a paradoxical finding reflecting the body's attempt to compensate for the lack of ADH.
B :x: Oxytocin is primarily involved in uterine contractions and milk ejection; it doesn't directly regulate water balance.
C :x: Growth hormone affects growth and metabolism, but not directly involved in this specific fluid imbalance.
D :x: Prolactin is primarily involved in lactation; it doesn't directly regulate water balance.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the symptoms of SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion) with central diabetes insipidus. SIADH presents with hyponatremia and inappropriately *low* urine osmolality.
   How to avoid: Carefully analyze the urine osmolality; high osmolality points towards ADH deficiency.
  2.Overlooking the importance of the paradoxical finding of high urine osmolality in the context of hyponatremia and adequate fluid intake.
   How to avoid:  Understand the interplay between ADH, kidney function, and electrolyte balance.
 **Quick Tips**:
  1.Remember that ADH is responsible for water reabsorption in the kidneys.
  2.High urine osmolality in the presence of hyponatremia is a strong indicator of ADH deficiency.

Mr. BALACHANDRA.N · Answer

The correct Option is "Vasopressin (ADH)"

Mr. BALACHANDRA.N · Answer

Oxytocin

Mr. BALACHANDRA.N · Answer

Growth Hormone (GH)

Mr. BALACHANDRA.N · Answer

Prolactin

NEET Zoology Chemical Coordination and Integration The Pituitary Gland MCQs

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