CKD Pathway - About CKD

Definition

Chronic Kidney Disease (CKD) is defined by:

eGFR < 60 mL/min/1.73m² that is present for ≥ 3 months
- or -
Markers of kidney damage present for ≥ 3 months:

Albuminuria ≥ 3 mg/mmol
Urine sediment abnormalities
Structural or pathological abnormalities

If eGFR is ≥ 60 mL/min/1.73m2 , and there are no markers of kidney damage, then CKD is not present

Classification

CKD is classified based on eGFR and albuminuria categories.

eGFR Categories:

Category	eGFR(mL/min/1.73 m²)	Description
G1	>90	Normal or high
G2	60-89	Mildly decreased
G3a	45–59	Mildly to moderately decreased (CKD)
G3b	30–44	Moderately to severely decreased (CKD)
G4	15–29	Severely decreased (CKD)
G5	<15	Kidney failure (CKD)

Albuminuria (ACR) Categories:

Category	ACR(mg/mmol)	Description
A1	<3 mg/mmol	Normal to mildly increased
A2	3-30 mg/mmol	Moderately increased (CKD)
A3	>30 mg/mmol	Severely increased (CKD)

General
information about random urine ACR

Random urine ACR:

Excess amounts of protein in urine are a marker of kidney damage and increase kidney disease and CVD risk.
Random urine ACR is preferred to detect proteinuria (ideally first morning void).
ACR has greater sensitivity than protein:creatinine ratio (PCR) for low levels of proteinuria.
ACR ≥3.0 mg/mmol for both men and women is clinically significant.

Approximate equivalent values of ACR, PCR and urinary protein excretion:

ACR (mg/mmol)	PCR (mg/mmol)	Urinary protein excretion (g/24h)
30	50	0.5
60	100	1

Factors affecting urinary ACR:

Factor	Examples of effect
Transient elevation in albuminuria	Menstrual blood contamination Symptomatic UTI Exercise Upright posture (orthostatic proteinuria) Other conditions increasing vascular permeability (e.g. septicemia)
Intraindividual variability	Intrinsic biological variability Genetic variability
Pre-analytical storage conditions	Degradation of albumin before analysis
Non-renal causes of variability in creatinine excretion	Age (lower in children and older people) Race (lower in Caucasian than black people) Muscle mass (e.g. lower in people with amputations, paraplegia, muscular dystrophy) Gender (lower in women)
Changes in creatinine excretion	Non-steady state for creatinine (AKI)

Prognosis and recommended frequency of testing per year

Early identification and management of CKD can reduce progression and cardiovascular risk. CKD prognosis for mortality, CVD and kidney function progression is determined by eGFR and albuminuria (ACR).

			Albuminuria (ACR) Categories
			A1	A2	A3
			<3 mg/mmol	3-30 mg/mmol	>30 mg/mmol
eGFR Categories	G1	≥90
	G2	60-89
	G3a	45-59
	G3b	30-44
	G4	15-29
	G5	<15

	Low risk

	Moderate risk Test annually		Very High risk Test 3 times per year

	High risk Test 2 times per year		Very high risk Test 4+ times per year

Learn more about the pathway

Learn more about who and how to test