Identifying patients with CKD stages G1 & G2
An eGFR of >90 ml/min/1.73m2 is considered normal kidney function. If these patients have evidence of kidney disease* (see below) these patients have CKD stage G1.
Patients with an eGFR of 60-90 ml/min/1.73m2 have mildly reduced kidney function which may be appropriate for their age. If these patients have other evidence of kidney disease* (see below) they have CKD stage G2.
*Evidence of kidney disease, required to diagnose CKD in patients with an eGFR >60 ml/min/1.7m2, may include:
- Haematuria (of presumed or proven renal origin)
- Structural abnormalities (e.g. reflux nephropathy, renal dysgenesis, medullary sponge kidney)
- A known diagnosis of a genetic kidney disease (e.g. polycystic kidney disease)
- Abnormalities detected by examination of renal histology
- Electrolyte abnormalities due to renal tubular disorders
- History of kidney transplantation
Remember that eGFR is only an estimate of kidney function (more info on eGFR). Ensure any corrections to the eGFR value for race have been made if appropriate.
Creatinine and eGFR values, for an individual patient, are usually fairly stable over time. Patients with deteriorating renal function require rapid assessment.
Initial assessment of CKD stages G1 and G2
The initial assessment of these patients should be undertaken in the primary care setting for the majority of patients. The aim of the initial assessment is to determine which patients are at risk of progressive renal disease.
- All patients should undergo reagent strip (“dipstick”) analysis of their urine to look for blood and / or protein. Additionally, all patients should have a urine specimen sent for measurement of the albumin:creatinine ratio (ACR). These specimens should be sent in plain / universal containers, not the specimen containers used for microbiological analysis which include a preservative.
- If assessment is precipitated by a first discovery of an elevated serum creatinine level it is important to ensure that the renal function is stable. Previous blood tests, if available, will give you the answer. If no previous blood tests are available and the patient is well with no other worrying features (e.g. high potassium, symptoms of bladder outflow tract obstruction, severe hypertension), repeat the test within 14 days. Patients with deteriorating renal function require rapid assessment.
- Measure blood pressure. CKD can be a consequence of hypertension and CKD of any aetiology can be associated with hypertension. An elevated serum creatinine level may be the first clue that a patient is hypertensive.
Management of CKD stages G1 and G2
This applies to patients with stable stages G1 and G2 CKD. To diagnose CKD, two or more blood tests are required at least 90 days apart. The CKD staging and management outlined below is predicated on stable renal function.
Almost all patients with stages G1 and G2 CKD can be appropriately managed in primary care. The principle aim is to identify individuals at risk of progressive renal disease.
Some patients need further investigation where there are indications that progression to end stage renal failure (Stage G5) may be a possibility. These patients should usually be referred to the local nephrology service. Pointers to progression of renal disease include:
- Proteinuria – the risk is graded but a common cut-off for further investigation in patients without diabetes is ACR>70 mg/mmol or PCR>100 mg/mmol
- Haematuria of renal origin
- Rapidly deteriorating renal function
- Young age – the referral threshold should be much lower for younger patients in whom the lifetime risk of developing progressive kidney disease is higher.
- Family history of renal failure
- Hypertension which is difficult to control
Risk of cardiovascular events and death is substantially increased by the presence of CKD and or proteinuria and the risks of these two are additive. Patients with stages G1 and G2 CKD are much more likely to suffer a cardiovascular event than they are to require renal replacement therapy (dialysis or a transplant) in their lifetime. Patients should be offered lifestyle advice including recommendations for regular exercise, smoking cessation and attainment and maintenance of a healthy weight.
Long term monitoring of renal function, proteinuria and blood pressure should be performed for all patients. The principle aim of long term monitoring is to identify the minority of patients with stage G1 and G2 CKD who will go on to develop progressive renal disease.
- Renal function and proteinuria – patients with a urine ACR >3 mg/mmol (i.e. A2 and A3) should undergo annual monitoring of renal function and proteinuria. Patients with ACR<3 mg/mmol may be monitored less frequently (see more on stages of CKD).
Patients with evidence of rapidly progressive renal impairment or who have worrying features (e.g. difficult to control hypertension, anaemia, hyperkalaemia, features of a systemic disease) should be considered for referral to renal services.
- Worsening proteinuria is an adverse prognostic sign. In patients with worsening proteinuria which exceeds ACR>70mg/mmol consider referral / discussion with nephrology unless it is known to be caused by diabetes and is appropriately treated. (see Referral Guidelines).
- Blood pressure – Aim to keep the BP <140/90. In patients with CKD and diabetes or an ACR>70 mg/mmol aim to keep BP<130/80. More on hypertension.
- Cardiovascular disease – Offer advice on smoking cessation, exercise and lifestyle. More on cardiovascular disease.
Patient information – CKD G1 and G2
CKD stage G1 is kidney disease with normal renal function. Patients with CKD stage G2 have mild impairment of kidney function. Most patients with CKD stages G1 and G2 just need occasional testing to ensure things are stable. A small minority of patients need further investigations to see if they have a disease which may benefit from treatment or could lead to more serious kidney damage.