Basic Principle of Renal Replacement Therapy

Full text:click here

Function of The Kidney (A WET BED)

Full text: click here

Diffusion & Osmosis

Full text: click here

✅ MCQs – Diffusion & Osmosis (Set 1)

1. In hemodialysis, diffusion primarily helps in the removal of:
A. Excess fluid
B. Large proteins
C. Electrolytes and urea
D. Blood cells
Answer: C. Electrolytes and urea

---

2. Diffusion is best described as the movement of solutes:
A. Against the concentration gradient
B. From an area of lower to higher concentration
C. From an area of higher to lower concentration
D. Via active transport
Answer: C. From an area of higher to lower concentration

---

3. Osmosis involves the movement of:
A. Solutes across a semi-permeable membrane
B. Water from high solute to low solute concentration
C. Water across a semi-permeable membrane toward higher solute concentration
D. Gases through a membrane
Answer: C. Water across a semi-permeable membrane toward higher solute concentration

---

4. In dialysis, which process is responsible for water removal?
A. Diffusion
B. Active transport
C. Osmosis
D. Ultrafiltration
Answer: D. Ultrafiltration

---

5. The rate of diffusion in dialysis is affected by all EXCEPT:
A. Concentration gradient
B. Temperature
C. Molecular size
D. Blood pressure
Answer: D. Blood pressure

---

6. Which of the following best explains why urea moves from blood to dialysate in dialysis?
A. Dialysate has higher urea concentration
B. Active transport moves urea out
C. There is a urea concentration gradient across the membrane
D. Dialysate pumps out urea
Answer: C. There is a urea concentration gradient across the membrane

---

7. Osmosis can be prevented or reversed by applying:
A. Negative pressure
B. Hydrostatic pressure (osmotic pressure)
C. Dialysate flow
D. Heat
Answer: B. Hydrostatic pressure (osmotic pressure)

---

8. What characteristic of the dialysis membrane allows diffusion to occur?
A. It is completely impermeable
B. It contains pores that allow selective passage of solutes
C. It actively transports solutes
D. It dissolves waste products
Answer: B. It contains pores that allow selective passage of solutes

---

9. In peritoneal dialysis, diffusion and osmosis occur across the:
A. Hemodialyzer membrane
B. Abdominal wall
C. Peritoneal membrane
D. Urethral lining
Answer: C. Peritoneal membrane

---

10. A patient is overhydrated. Which dialysate property promotes water removal by osmosis?
A. Low potassium concentration
B. High bicarbonate concentration
C. Low sodium concentration
D. High glucose concentration
Answer: D. High glucose concentration
(Used in peritoneal dialysis to draw water via osmosis)

11. Which condition would decrease the rate of diffusion during dialysis?
A. Increased dialysate flow rate
B. Higher concentration gradient
C. Thicker dialysis membrane
D. Warmer dialysate
Answer: C. Thicker dialysis membrane

---

12. In osmosis, water moves toward which of the following?
A. Lower solute concentration
B. Higher solute concentration
C. Higher temperature
D. Higher pressure area
Answer: B. Higher solute concentration

---

13. What is the driving force for solute movement in diffusion?
A. Hydrostatic pressure
B. Electrical charge
C. Concentration gradient
D. ATP energy
Answer: C. Concentration gradient

---

14. In hemodialysis, which of the following substances primarily uses diffusion to move across the membrane?
A. Water
B. Sodium bicarbonate
C. Albumin
D. Urea
Answer: D. Urea

---

15. Osmotic pressure can be increased in dialysate by adding more:
A. Sodium
B. Glucose
C. Potassium
D. Urea
Answer: B. Glucose

---

16. A smaller molecular weight solute will diffuse:
A. Slower than a larger one
B. Faster than a larger one
C. At the same rate as a larger one
D. Not at all
Answer: B. Faster than a larger one

---

17. What happens to diffusion if there is no concentration gradient?
A. It increases
B. It stops
C. It reverses
D. It becomes active transport
Answer: B. It stops

---

18. The direction of water flow in osmosis depends on:
A. Temperature only
B. Solute concentration difference
C. Blood pressure
D. Electrical gradients
Answer: B. Solute concentration difference

---

19. Which of the following is a common example of osmosis in clinical dialysis?
A. Movement of potassium into blood
B. Removal of excess fluid via glucose dialysate in peritoneal dialysis
C. Urea clearance
D. Blood pressure monitoring
Answer: B. Removal of excess fluid via glucose dialysate in peritoneal dialysis

---

20. Which best describes the role of the semipermeable membrane in dialysis?
A. It prevents fluid movement
B. It allows all substances to pass
C. It blocks glucose movement
D. It allows selective diffusion of solutes and osmosis of water
Answer: D. It allows selective diffusion of solutes and osmosis of water

---

21. During hemodialysis, why are certain solutes like albumin not removed by diffusion?
A. They are not toxic
B. They have low molecular weight
C. They are too large to pass through the membrane pores
D. They bind to water molecules
Answer: C. They are too large to pass through the membrane pores

---

22. Which of the following best increases diffusion efficiency in hemodialysis?
A. Smaller surface area of membrane
B. Higher dialysate flow rate
C. Low blood flow rate
D. Low temperature dialysate
Answer: B. Higher dialysate flow rate

---

23. A higher concentration of sodium in dialysate compared to blood would cause sodium to:
A. Move into the blood
B. Be actively transported
C. Remain unchanged
D. Move from dialysate to blood via diffusion
Answer: D. Move from dialysate to blood via diffusion

---

24. In dialysis, when the concentration of a solute is the same on both sides of the membrane, diffusion will:
A. Continue at the same rate
B. Reverse direction
C. Stop
D. Turn into osmosis
Answer: C. Stop

---

25. The semipermeable membrane in a dialyzer allows passage of:
A. Blood cells and proteins only
B. Solutes and large proteins
C. Small solutes and water
D. All plasma components
Answer: C. Small solutes and water

---

26. Which clinical sign may suggest osmotic imbalance during dialysis?
A. Fever
B. Seizure
C. Edema
D. Hypertension
Answer: B. Seizure
(May result from rapid osmotic shifts e.g., in Dialysis Disequilibrium Syndrome)

---

27. A key distinction between diffusion and osmosis is that:
A. Osmosis requires ATP
B. Diffusion involves water only
C. Osmosis involves movement of water, diffusion involves solutes
D. Both require equal concentrations
Answer: C. Osmosis involves movement of water, diffusion involves solutes

---

28. What happens to osmosis if the solute concentration is equal on both sides?
A. Continues rapidly
B. Slows but continues
C. Reverses direction
D. Net movement of water stops
Answer: D. Net movement of water stops

---

29. Which of the following can reduce osmotic water removal in peritoneal dialysis?
A. Higher glucose in dialysate
B. Longer dwell time
C. Low glucose concentration in dialysate
D. Increasing solute in blood
Answer: C. Low glucose concentration in dialysate

---

30. In hemodialysis, the process that uses both diffusion and convection to enhance solute removal is called:
A. Osmosis
B. Filtration
C. Hemodiafiltration
D. Reverse osmosis
Answer: C. Hemodiafiltration

---

31. In hemodialysis, urea is removed primarily by:
A. Osmosis
B. Ultrafiltration
C. Convection
D. Diffusion
Answer: D. Diffusion

---

32. In peritoneal dialysis, what causes water to move into the peritoneal cavity?
A. Low dialysate volume
B. High blood pressure
C. High glucose concentration in dialysate
D. High protein concentration in blood
Answer: C. High glucose concentration in dialysate

---

33. Which membrane characteristic increases the rate of diffusion?
A. Small surface area
B. Low permeability
C. Increased thickness
D. Large surface area
Answer: D. Large surface area

---

34. In diffusion, which of the following does NOT affect the rate?
A. Membrane thickness
B. Solute size
C. Temperature
D. Patient's weight
Answer: D. Patient's weight

---

35. What term describes the movement of solutes along with water during convection?
A. Osmotic drag
B. Solute dragging
C. Solvent dragging
D. Solute diffusion
Answer: C. Solvent dragging

---

36. Dialysis disequilibrium syndrome can occur due to:
A. Slow removal of urea by osmosis
B. Rapid shift of urea due to diffusion
C. Excess glucose in dialysate
D. Decreased convection
Answer: B. Rapid shift of urea due to diffusion

---

37. When does back-diffusion occur in dialysis?
A. When blood pressure drops
B. When dialysate concentration is higher than blood
C. When membrane pores collapse
D. When dialysate purity is compromised
Answer: B. When dialysate concentration is higher than blood

---

38. Which dialysis mode best combines both convection and diffusion?
A. SLED
B. Peritoneal Dialysis
C. Hemodiafiltration (HDF)
D. CRRT
Answer: C. Hemodiafiltration (HDF)

---

39. Why is temperature important in diffusion during dialysis?
A. Higher temperature increases blood viscosity
B. Lower temperature increases solute clearance
C. Warmer solutions speed up molecular movement
D. Temperature does not affect diffusion
Answer: C. Warmer solutions speed up molecular movement

---

40. Which solute is least likely to pass by diffusion through the dialysis membrane?
A. Sodium
B. Urea
C. Bicarbonate
D. Albumin
Answer: D. Albumin
(Too large to pass through standard dialysis membranes)

41. What is the main difference between diffusion and convection in solute transport?
A. Diffusion requires energy, convection does not
B. Diffusion depends on pressure gradient, convection on concentration gradient
C. Diffusion is passive, convection uses pressure to drag solutes
D. Convection occurs only in peritoneal dialysis
Answer: C. Diffusion is passive, convection uses pressure to drag solutes

---

42. Which of the following changes would enhance osmosis in peritoneal dialysis?
A. Lower dialysate temperature
B. Decreasing glucose in dialysate
C. Increasing glucose in dialysate
D. Increasing protein in dialysate
Answer: C. Increasing glucose in dialysate

---

43. Which factor most affects the direction of solute diffusion during hemodialysis?
A. Blood pressure
B. Dialyzer type
C. Concentration gradient between blood and dialysate
D. Flow rate of the blood pump
Answer: C. Concentration gradient between blood and dialysate

---

44. What will happen if a patient’s dialysate sodium concentration is higher than their serum sodium?
A. Sodium will diffuse into the dialysate
B. Sodium will move into the blood
C. Water will follow sodium out of the blood
D. Water removal will decrease
Answer: B. Sodium will move into the blood

---

45. What causes diffusion to occur faster across the dialysis membrane?
A. Decreased temperature
B. Thicker membrane
C. Large surface area and high solute gradient
D. Reduced blood flow
Answer: C. Large surface area and high solute gradient

---

46. Which of the following molecules will not easily diffuse through a standard dialysis membrane?
A. Glucose
B. Potassium
C. Creatinine
D. Hemoglobin
Answer: D. Hemoglobin

---

47. What best describes the net movement of water during osmosis?
A. From high pressure to low pressure
B. From low to high solute concentration
C. From high solute to low solute concentration
D. From high protein to low protein content
Answer: B. From low to high solute concentration

---

48. Which statement is TRUE regarding osmosis in peritoneal dialysis?
A. It occurs from blood to dialysate due to protein gradients
B. Water moves into blood vessels due to sodium
C. It is independent of glucose concentration
D. It drives fluid removal using osmotic agents
Answer: D. It drives fluid removal using osmotic agents

---

49. Which factor is least likely to affect the rate of solute diffusion in dialysis?
A. Membrane surface area
B. Molecular size of solute
C. Patient's age
D. Temperature
Answer: C. Patient's age

---

50. Diffusion in dialysis always occurs:
A. Against the concentration gradient
B. Along the pressure gradient
C. From high solute concentration to low
D. With ATP assistance
Answer: C. From high solute concentration to low

51. In hemodialysis, which condition would reduce the effectiveness of diffusion?
A. High blood flow rate
B. Low dialysate flow rate
C. High concentration gradient
D. Thin membrane
Answer: B. Low dialysate flow rate

(Reduced dialysate flow decreases solute clearance due to slower exchange.)

---

52. What happens if the dialysate potassium concentration is set too low?
A. Potassium diffuses into the blood
B. Patient may develop hyperkalemia
C. Excess potassium is retained
D. Patient may develop hypokalemia
Answer: D. Patient may develop hypokalemia

---

53. Which process is responsible for removal of small, water-soluble molecules during standard HD?
A. Filtration
B. Absorption
C. Diffusion
D. Adsorption
Answer: C. Diffusion

---

54. What is a common risk of high osmotic gradient during peritoneal dialysis?
A. Low ultrafiltration
B. Excess water reabsorption
C. Dehydration
D. Increased potassium
Answer: C. Dehydration

(High glucose dialysate draws too much water out of blood.)

---

55. Which molecule is least influenced by changes in dialysate composition?
A. Potassium
B. Bicarbonate
C. Albumin
D. Urea
Answer: C. Albumin

(Albumin is too large to cross most dialysis membranes.)

---

How To Interpret Urea Kinetic Parameters (KT/V)

Full Text: Click here

Reverse Osmosis Water Treatment

Full text :Click here

✅ Reverse Osmosis in Hemodialysis – MCQ Set 5

41. Which type of RO membrane cleaning is typically required when scaling occurs?
A. Acid cleaning
B. Alkaline cleaning
C. Alcohol-based rinsing
D. UV disinfection
➡️ Answer: A. Acid cleaning

(Used to remove calcium and magnesium deposits.)

---

42. If an RO system’s rejection rate drops significantly, the first check should be:
A. RO membrane pH
B. Source water temperature
C. Conductivity of product and feed water
D. Dialysate temperature
➡️ Answer: C. Conductivity of product and feed water

(This helps assess membrane efficiency.)

43. A properly functioning RO system typically produces how much product water compared to feed water?
A. 90–95%
B. 75–80%
C. 50–70%
D. 10–20%
➡️ Answer: C. 50–70%

(The rest is waste/reject water.)

---

44. Which water treatment component protects the RO membrane from mechanical damage due to particles?
A. UV filter
B. Carbon tank
C. Micron prefilter (e.g. 5 or 1 micron)
D. Deionizer

➡️ Answer: C. Micron prefilter

45. According to AAMI, the action level for total viable bacteria in dialysis water is:
A. 50 CFU/mL
B. 100 CFU/mL
C. 200 CFU/mL
D. 500 CFU/mL
➡️ Answer: B. 50 CFU/mL

(Action level = initiate corrective action. Maximum allowable = 100 CFU/mL.)

---

46. What is the ideal temperature range for RO water entering the membrane?
A. 5–10°C
B. 10–15°C
C. 20–30°C
D. 40–60°C
➡️ Answer: C. 20–30°C

(High temperatures can damage membranes; cold water reduces efficiency.)

47. An RO system alarm indicates low pressure in the feed water line. The technician should first:
A. Replace the membrane
B. Check incoming water supply and booster pump
C. Call biomedical engineer
D. Ignore and restart the system
➡️ Answer: B. Check incoming water supply and booster pump

---

48. What is the AAMI maximum allowable level of nitrate (as nitrogen) in dialysis water?
A. 0.1 mg/L
B. 1.0 mg/L
C. 2.0 mg/L
D. 10.0 mg/L

➡️ Answer: C. 2.0 mg/L

49. What is the recommended location for collecting water samples for endotoxin testing in a dialysis unit?
A. Directly from the city water source
B. After carbon filter
C. After RO system, before entering dialysis machine
D. From drain line of RO unit
➡️ Answer: C. After RO system, before entering dialysis machine

(Sampling should represent the water patients are exposed to.)

---

50. According to best practice, how often should carbon tanks be tested for total chlorine/chloramine breakthrough?
A. Before each dialysis shift
B. Once per week
C. Only when patients report symptoms
D. After every water softener regeneration

➡️ Answer: A. Before each dialysis shift

51. What is the recommended pore size of an ultrafilter used after the RO system in dialysis?
A. 10 µm
B. 5 µm
C. 0.2 µm
D. 1.0 µm
➡️ Answer: C. 0.2 µm

(Used to remove bacteria and endotoxins post-RO.)

---

52. In a double-pass RO system, the second RO membrane receives water from:
A. City water directly
B. Final dialysate line
C. Product of the first RO pass
D. Reject line of first RO pass
➡️ Answer: C. Product of the first RO pass

(Double-pass improves purity by passing product water again.)

53. What is the most sensitive method for detecting endotoxins in dialysis water?
A. Total chlorine strip
B. Turbidity test
C. Limulus Amebocyte Lysate (LAL) assay
D. Dipstick urinalysis
➡️ Answer: C. Limulus Amebocyte Lysate (LAL) assay

---

54. Which condition can lead to increased bacterial contamination in RO systems?
A. Low water temperature
B. Daily disinfection
C. Continuous recirculation
D. Stagnant water in dead legs
➡️ Answer: D. Stagnant water in dead legs

(Dead legs allow biofilm growth.)

55. Which of the following would be a cause of high product water conductivity in the RO system?
A. Fresh carbon filter
B. Proper membrane rejection
C. Compromised RO membrane
D. Cold incoming water
➡️ Answer: C. Compromised RO membrane

---

56. Which one is a benefit of continuous loop distribution of RO water in dialysis units?
A. Reduces energy use
B. Eliminates bacteria completely
C. Minimizes stagnation and bacterial growth
D. Reduces flow rate

➡️ Answer: C. Minimizes stagnation and bacterial growth

57. According to AAMI, the minimum RO rejection percentage for proper performance is:
A. 70%
B. 75%
C. 80%
D. 90%
➡️ Answer: D. 90%

---

58. Which disinfection method is commonly used for heat-tolerant RO systems?
A. Citric acid flush
B. Chlorine flush
C. Heat disinfection (pasteurization)
D. UV light
➡️ Answer: C. Heat disinfection (pasteurization)

---

59. Which of the following is not removed effectively by RO and requires pretreatment?
A. Sodium
B. Lead
C. Chloramines
D. Fluoride

➡️ Answer: C. Chloramines

60. In dialysis centers, why is conductivity monitoring of RO product water performed continuously?
A. To ensure the correct dialysate temperature
B. To detect membrane failure in real time
C. To monitor bacterial count
D. To measure chlorine/chloramine

➡️ Answer: B. To detect membrane failure in real time