Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): The primary cause of anemia in chronic kidney disease (CKD) is inadequate secretion of erythropoietin (EPO) by the kidneys.
Reason (R): The EPO is a glycoprotein hormone that is produced in the kidneys in response to decreased oxygen delivery.
In light of the above statements, choose the correct answer from the options given below:

• A. Both (A) and (R) are true and (R) is not correct explanation of (A).
• B. Both (A) and (R) are true and (R) is the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Remember that the kidneys produce about 90% of the body's erythropoietin. Consequently, chronic kidney failure directly leads to a deficiency in EPO, causing non-regenerative anemia.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Chronic kidney disease (CKD) is characterized by a progressive, irreversible loss of functioning nephrons, leading to uremia and systemic complications, including non-regenerative anemia.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A): In animals with CKD, the progressive destruction of renal parenchyma leads to a severe deficiency in the synthesis and secretion of erythropoietin (EPO). Because EPO is the primary hormone that stimulates red blood cell production in the bone marrow, its inadequate secretion is the direct and primary cause of the non-regenerative anemia observed in CKD patients. Thus, Assertion (A) is true.
- Reason (R): Erythropoietin (EPO) is indeed a glycoprotein hormone. It is primarily synthesized and released by specialized peritubular interstitial cells in the renal cortex. Its production is tightly regulated by tissue oxygen levels, increasing significantly in response to renal hypoxia (decreased oxygen delivery). Thus, Reason (R) is true.
- Causal Link: Because the kidneys are the primary site of EPO production in response to oxygen levels, the chronic loss of functioning renal tissue directly impairs the body's ability to secrete adequate EPO, resulting in anemia. Therefore, (R) is the correct physiological explanation of (A).
Note: On this exam paper, option (B) is designated as "is the correct explanation."

Step 3: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A), which corresponds to option (B).