Certified Dialysis Nurse (CDN) WITH CORRECT
ACTUAL QUESTIONS AND CORRECTLY WELL
DEFINED ANSWERS LATEST ALREADY GRADED A+
(2025/2026)
Question 1
What is the primary functional unit of the kidney
responsible for filtering blood?
A) Nephron
B) Glomerulus
C) Bowman capsule
D) Loop of Henle
Answer: A) Nephron
Rationale: The nephron is the structural and functional unit
of the kidney, consisting of the glomerulus, Bowman
capsule, proximal tubule, loop of Henle, distal tubule, and
collecting duct. While the glomerulus performs filtration,
the nephron as a whole performs all kidney functions.
1
,Question 2
A patient has a GFR of 25 mL/min. According to KDOQI
staging, which stage of CKD is this?
A) Stage 3a
B) Stage 3b
C) Stage 4
D) Stage 5
Answer: C) Stage 4
Rationale: Stage 4 CKD is defined by a GFR of 15–29
mL/min, indicating severe kidney dysfunction. Stage 5 is
<15 mL/min (kidney failure), Stage 3a is 45–59, and
Stage 3b is 30–44.
Question 3
Which hormone, produced by the kidneys, stimulates red
blood cell production in the bone marrow?
A) Renin
2
,B) Calcitriol
C) Erythropoietin
D) Aldosterone
Answer: C) Erythropoietin
Rationale: Erythropoietin (EPO) is produced by
peritubular fibroblasts in the kidney in response to
hypoxia. It stimulates erythropoiesis. Renin regulates
blood pressure, calcitriol regulates calcium absorption,
and aldosterone is produced by the adrenal cortex.
Question 4
In chronic kidney disease, which electrolyte imbalance is
most commonly associated with the development of
cardiac arrhythmias?
A) Hyponatremia
B) Hyperkalemia
C) Hypocalcemia
D) Hypermagnesemia
3
, Answer: B) Hyperkalemia
Rationale: Hyperkalemia (elevated serum potassium) is a
life-threatening complication of CKD due to decreased
renal excretion. It can cause peaked T waves, widened
QRS, and fatal ventricular arrhythmias. Other electrolyte
disturbances occur but are less acutely arrhythmogenic.
Question 5
What is the normal range for serum creatinine in an adult
with normal kidney function?
A) 0.2–0.5 mg/dL
B) 0.6–1.2 mg/dL
C) 1.5–2.0 mg/dL
D) 2.5–3.0 mg/dL
Answer: B) 0.6–1.2 mg/dL
Rationale: Normal serum creatinine ranges from
approximately 0.6 to 1.2 mg/dL, varying slightly by
4
ACTUAL QUESTIONS AND CORRECTLY WELL
DEFINED ANSWERS LATEST ALREADY GRADED A+
(2025/2026)
Question 1
What is the primary functional unit of the kidney
responsible for filtering blood?
A) Nephron
B) Glomerulus
C) Bowman capsule
D) Loop of Henle
Answer: A) Nephron
Rationale: The nephron is the structural and functional unit
of the kidney, consisting of the glomerulus, Bowman
capsule, proximal tubule, loop of Henle, distal tubule, and
collecting duct. While the glomerulus performs filtration,
the nephron as a whole performs all kidney functions.
1
,Question 2
A patient has a GFR of 25 mL/min. According to KDOQI
staging, which stage of CKD is this?
A) Stage 3a
B) Stage 3b
C) Stage 4
D) Stage 5
Answer: C) Stage 4
Rationale: Stage 4 CKD is defined by a GFR of 15–29
mL/min, indicating severe kidney dysfunction. Stage 5 is
<15 mL/min (kidney failure), Stage 3a is 45–59, and
Stage 3b is 30–44.
Question 3
Which hormone, produced by the kidneys, stimulates red
blood cell production in the bone marrow?
A) Renin
2
,B) Calcitriol
C) Erythropoietin
D) Aldosterone
Answer: C) Erythropoietin
Rationale: Erythropoietin (EPO) is produced by
peritubular fibroblasts in the kidney in response to
hypoxia. It stimulates erythropoiesis. Renin regulates
blood pressure, calcitriol regulates calcium absorption,
and aldosterone is produced by the adrenal cortex.
Question 4
In chronic kidney disease, which electrolyte imbalance is
most commonly associated with the development of
cardiac arrhythmias?
A) Hyponatremia
B) Hyperkalemia
C) Hypocalcemia
D) Hypermagnesemia
3
, Answer: B) Hyperkalemia
Rationale: Hyperkalemia (elevated serum potassium) is a
life-threatening complication of CKD due to decreased
renal excretion. It can cause peaked T waves, widened
QRS, and fatal ventricular arrhythmias. Other electrolyte
disturbances occur but are less acutely arrhythmogenic.
Question 5
What is the normal range for serum creatinine in an adult
with normal kidney function?
A) 0.2–0.5 mg/dL
B) 0.6–1.2 mg/dL
C) 1.5–2.0 mg/dL
D) 2.5–3.0 mg/dL
Answer: B) 0.6–1.2 mg/dL
Rationale: Normal serum creatinine ranges from
approximately 0.6 to 1.2 mg/dL, varying slightly by
4
