Chronic Kidney Disease Quiz

See Stages of Chronic Kidney Disease. Option C is correct: stage 4 (GFR category G4) is a GFR of 15 to 29 mL/min/1.73 m², which NICE describes as a severe reduction. The glomerular filtration rate (GFR) is the volume of blood the kidneys filter each minute (the 1.73 m² means it is adjusted to an average body surface area), and in practice it is estimated (eGFR) from the blood creatinine level. A healthy GFR is about 90 to 120, so at stage 4 only around a sixth to a quarter of normal filtration is left. Complications of CKD such as raised potassium, acidosis (too much acid in the blood), anaemia and mineral and bone disease become more of a concern as the GFR falls, and NICE advises measuring calcium, phosphate and parathyroid hormone when the GFR is below 30. The boundaries to know are:

• G3a: 45 to 59 (mild to moderate reduction)
• G3b: 30 to 44 (moderate to severe reduction)
• G4: 15 to 29 (severe reduction)
• G5: below 15 (kidney failure)

• Stage: stage 4, GFR category G4.
• Range: a GFR of 15 to 29.
• NICE description: a severe reduction.
• Filtration left: only around a sixth to a quarter of normal.