Definition and classification

Intention of important international and national guidelines

Based on our commitment for excellence and continuous improvement, we at NephroCare acknowledge existing international and European national guidelines for the implementation into our working procedures and daily routines.

Specifically we base our work on the following guidelines:

KDIGO - International guideline1

The Kidney Disease: Improving Global Outcomes (KDIGO) 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (CKD) serves to update the 2002 KDOQI Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification following a decade of focused research and clinical practice in CKD.

The document aims to provide state-of-the-art guidance on the evaluation, management and treatment of all patients with CKD. Specifically, the guideline retains the definition of CKD but presents an enhanced classification framework for CKD; elaborates on the identification and prognosis of CKD; discusses the management of progression and complications of CKD; and expands on the continuum of CKD care: timing of specialist referral, ongoing management of people with progressive CKD, timing of the initiation of dialysis, and finally the implementation of a treatment programme which includes comprehensive conservative management.1

It is important to keep in mind that there is a close connection and collaboration between KDIGO and the Advisory Board of European Renal Best Practice (ERBP) as many members of the Advisory Board of ERBP also play an active role in KDIGO.2

Consensus document for the detection and management of chronic kidney disease - a European national guideline from Spain3

The executive consensus document of ten scientific societies involved in the care of the renal patient is an update of the consensus document published in 2007. This consensus document arises from the need to revise and update the previous document developed in 2007 by S.E.N.-SEMFyC (Spanish Society of Family and Community Medicine) on CKD, after an extensive review of the most recent literature and the latest clinical practice recommendations.

The document includes aspects like concept, epidemiology and risk factors for CKD; diagnostic criteria, evaluation and stages of CKD, albuminuria and glomerular filtration rate estimation; progression factors for renal damage; patient remission criteria; follow-up and objectives of each speciality control; nephrotoxicity prevention; cardiovascular damage detection; diet, life-style and treatment attitudes (hypertension, dyslipidemia, hyperglycaemia, smoking, obesity, hyperuricemia, anaemia, mineral and bone disorders); multidisciplinary management for Primary Care, other specialities and Nephrology; integrated management of the CKD patient in haemodialysis, peritoneal dialysis and renal transplant patients; management of the uraemic patient in palliative care.3

The NICE clinical guideline on Chronic Kidney Disease - early identification and management of chronic kidney disease in adults in primary and secondary Care - a European national guideline from the UK4

The guideline updates and replaces NICE clinical guideline 73. It was developed by the National Clinical Guideline Centre, which is based at the Royal College of Physicians. The Centre worked with a Guideline Development Group, comprising healthcare professionals (including consultants, GPs and nurses), patients and carers, and technical staff, which reviewed the evidence and drafted the recommendations. The recommendations were finalised after public consultation.4

Further national guidelines do exist and within our network we will foster the best practices. 

Definition and stages of CKD

Humans have approximately 2 million nephrons, each of which filters 60 ml/minute on average, and consequently an overall glomerular filtration rate (GFR) of 120 ml/minute is reached. Renal failure starts when the GFR falls below 60 ml/min/1.73m2.

The determination of creatinine is not considered to be a good measure of renal function, since creatinine depends on muscle mass, age, sex and tubular secretion among other factors. It is very important to emphasise the physiological reduction of the kidney function of around 10% for each decade of life. The kidney is able to lose up to 50% of its function without reflecting an increase in serum creatinine.

 The nephrological community defines CKD as abnormalities of kidney structure or function, present for >3 months, with implications for health.

Abnormalities of kidney function: Decreased GFR1

  • Decreased GFR (<60 ml/min/1.73 m2, GFR categories G3a-G5)

Chronic renal failure is defined as a decrease in the glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m2 or the presence of kidney damage over at least three months.

The kidney has many functions, including excretory, endocrine and metabolic functions. Excretory, endocrine and metabolic functions decline together in most chronic kidney diseases. The GFR is one component of excretory function, but is widely accepted as the best overall index of kidney function. GFR is generally accepted as the best overall index of kidney function.1 

The nephrological community chose a threshold of GFR <60 ml/min/1.73 m2 (GFR categories G3a-G5) for >3 months to indicate CKD. A GFR <60 ml/min/1.73 m2 is less than half the normal value in young adult men and women of approximately 125 ml/min/1.73 m2.1

Abnormality of kidney structure/ markers for kidney damage:

  • Albuminuria (AER ≥30 mg/24 hours; ACR ≥30 mg/g (≥3 mg/mmol)
  • Urine sediment abnormalities
  • Electrolyte and other abnormalities due to tubular disorders
  • Abnormalities detected by histology
  • Structural abnormalities detected by imaging
  • History of kidney transplantation1


Albuminuria refers to abnormal loss of albumin in the urine. Albumin is one type of plasma protein found in the urine of normal subjects and in larger quantities in patients with kidney disease. For a number of reasons, clinical terminology is changing to focus on albuminuria rather than proteinuria. Albuminuria is a common but not uniform finding in CKD. It is the earliest marker of glomerular diseases, including diabetic glomerulosclerosis, where it generally appears before the reduction in GFR. It is a marker of hypertensive nephrosclerosis but may not appear until after the reduction in GFR. It is often associated with underlying hypertension, obesity, and vascular disease, where the underlying renal pathology is not known.1

The nephrological community chose a threshold for urinary Albumin Excretion Rate (AER) of >30 mg/ 24 hours sustained for >3 months to indicate CKD.1

Chronic renal failure (CRF) is classified into 5 levels of increasing severity. Its complications are related to each stage and treatment recommendations must be adapted according to each stage.1