early identification of CKD in primary care

Last edited 09/2021 and last reviewed 09/2021

Identification of risk groups:

• testing for CKD should be offered if people have any of the following risk factors:
  • diabetes
  • hypertension
  • cardiovascular disease (ischaemic heart disease, chronic heart failure, peripheral vascular disease and cerebral vascular disease)
  • structural renal tract disease, renal calculi or prostatic hypertrophy
  • multisystem diseases with potential kidney involvement - for example, systemic lupus erythematosus
  • family history of stage 5 CKD or hereditary kidney disease
  • incidental detection of haematuria or proteinuria
• do not use any of the following as risk factors indicating testing for CKD in adults, children and young people:
  • age
  • gender
  • ethnicity
  • obesity in the absence of metabolic syndrome, diabetes or hypertension.
• monitor adults, children and young people for the development or progression of CKD for at least 3 years after acute kidney injury (longer for people with acute kidney injury stage 3) even if eGFR has returned to baseline
• monitor GFR in people prescribed drugs known to be nephrotoxic such as calcineurin inhibitors and lithium. Check GFR at least annually in people receiving long-term systemic non-steroidal anti-inflammatory drug (NSAID) treatment

Testing for CKD: eGFR and albumin:creatinine ratio

• clinicians should use urine albumin:creatinine ratio (ACR) in preference to protein:creatinine ration (PCR) in order to detect proteinuria
  • ACR has greater sensitivity than protein:creatinine ratio (PCR) for low levels of proteinuria. For quantification and monitoring of proteinuria, PCR can be used as an alternative. ACR is the recommended method for people with diabetes
• for the initial detection of proteinuria, if the ACR is between 3 mg/mmol and 70 mg/mmol, this should be confirmed by a subsequent early morning sample. If the initial ACR is 70 mg/mmol or more, a repeat sample need not be tested
• regard a confirmed ACR of 3 mg/mmol or more as clinically important proteinuria

  Quantify urinary albumin or urinary protein loss as in recommendation

  • all people with diabetes, and people without diabetes with a GFR less than 60 ml/min/1.73 m^2, should have their urinary albumin/protein excretion quantified. The first abnormal result should be confirmed on an early morning sample (if not previously obtained)
• quantify by laboratory testing the urinary albumin/protein excretion of people with an eGFR 60 ml/min/1.73 m^2 or more if there is a strong suspicion of CKD
  
  

Frequency of monitoring - Frequency of monitoring of GFR (number of times per year, by GFR and ACR category) for people with, or at risk of, CKD

• use table below to guide the frequency of GFR monitoring (per year) for people with, or at risk of, CKD, but tailor it to the person according to:
  • the underlying cause of CKD
  • past patterns of eGFR and ACR (but be aware that CKD progression is often nonlinear)
  • comorbidities, especially heart failure
  • changes to their treatment (such as renin-angiotensin-aldosterone system [RAAS] antagonists, NSAIDs and diuretics)
  • intercurrent illness whether they have chosen conservative management of CKD

GFR ( ml/min/1.73 m^2) and ACR categories and risk of adverse outcomes		A1 < 3 mg/mol (normal to mildly increased)	A2 3 -30 mg/mol (moderately increased)	A3 > 30mg/mol (severely increased)
G1	>= 90 ml/min/1.73 m^2 (Normal and High)	check eGFR <=1 time per year	check eGFR 1 time per year	check eGFR >=1 time per year
G2	60-89 ml/min/1.73 m^2 (Mild reduction related to normal range for young adult)	check eGFR <=1time per year	check eGFR 1 time per year	check eGFR >=1time per year
G3a	45-59 ml/min/1.73 m^2 (mild-moderate reduction)	check eGFR 1time per year	check eGFR 1 time per year	check eGFR 2 times per year
G3b	30-44 ml/min/1.73 m^2 (moderate-severe reduction)	check eGFR <=2 times per year	check eGFR 2 times per year	check eGFR >=2 times per year
G4	15-29 ml/min/1.73 m^2 (severe reduction)	check eGFR 2 times per year	check eGFR 2 times per year	check eGFR 3 times per year
G5	< 15 ml/min/1.73 m^2 (kidney failure)	check eGFR 4 times per year	check eGFR >=4 times per year	check eGFR >=4 times per year

ACR (albumin creatinine ratio) category	ACR (mg/mmol)
A1	<3
A2	3-30*
A3	>30**

Using the Table - some examples:

• CKD G3a A1 - CKD stage 3 A with an ACR less than 3 mg/mmol has a suggested requirement of x1 GFR measurement per year i.e. yearly monitoring
  
  
• CKD G3a A3 - CKD stage 3A with an ACR > 30mg/mmol has a suggested requirement of x2 GFR measurements per year i.e. 6 monthly monitoring
  
  
• CKD G5 A2- CKD stage 5 with an ACR between 3 and 30 mg/mmol has suggested requirement of >=4 GFR measurements per year

* Relative to young adult level

** Including nephrotic syndrome (ACR usually >220 mg/mmol)

Abbreviations: ACR, albumin:creatinine ratio; CKD, chronic kidney disease

Monitor people for the development or progression of CKD for at least 2-3 years after acute kidney injury, even if serum creatinine has returned to baseline

• where a highly accurate measure of GFR is required - for example, during monitoring of chemotherapy and in the evaluation of renal function in potential living donors - consider a gold standard measure (inulin, 51Cr-EDTA, 125I-iothalamate or iohexol)

• Defining progression
  • define accelerated progression of CKD as:
    • a sustained decrease in GFR of 25% or more and a change in GFR category within 12 months
    • or a sustained decrease in GFR of 15 ml/min/1.73 m2 per year
      
      
  • take the following steps to identify the rate of progression of CKD:
    • obtain a minimum of 3 GFR estimations over a period of not less than 90 days
    • in people with a new finding of reduced GFR, repeat the GFR within 2 weeks to exclude causes of acute deterioration of GFR- for example, acute kidney injury or starting renin-angiotensin system antagonist therapy
      
      
  • be aware that people with CKD are at increased risk of progression to endstage kidney disease if they have either of the following:
    • a sustained decrease in GFR of 25% or more over 12 months or
    • a sustained decrease in GFR of 15 ml/min/1.73 m^2 or more over 12 months
      
      
  
  

Reference:

• (1) The Renal Association (May 2006).UK CKD Guidelines
• (2) NICE (August 2021). Chronic Kidney Disease - assessment and management