4th July 2024

Chronic kidney disease

Background

Chronic kidney disease (CKD) is defined by abnormalities in the function or structure of the kidney which is present for more than 3 months. This can also be defined as a glomerular filtration rate (GFR) of <60mL/minute/1.73m² or abnormal kidney structure or albuminuria. GFR and albuminuria are used to stage CKD. The former is based on age, sex, height and serum creatinine and cystatin C.  The most common causes of CKD are diabetes, hypertension, and glomerulonephritis. Complications are progressive, based on the level of CKD, and can include hypertension, anaemia, electrolyte disturbance, and end-stage renal failure.

Diagnosis

CKD is often asymptomatic, particularly in the early stages. Symptoms tend to occur in association with complications.  The most common of those are hormonal and metabolic complications such as anaemia, hyperparathyroidism and risks associated with systemic drug toxicity, cardiovascular disease, and infection. End-stage renal failure (ESRF) generally refers to CKD requiring dialysis or transplantation.

Staging

Staging is used to guide management and predict the risk of progression to complications. This is then used as a guide to inform appropriate monitoring and treatment strategy. GFR is divided into 6 categories for the purpose of staging, as highlighted in Table 1. G3 has been divided into 3a and 3b owing to evidence which demonstrated increasing mortality and adverse kidney outcomes associated with a continuous decrease in GFR. Albuminuria is also used in staging. This is again divided into stages, with none, microalbuminuria, (now referred to as ‘moderately increased’) and macroalbuminuria, (now referred to as severely increased/nephrotic range). Albuminuria is significant due to a correlated risk of progression to ESRF and mortality independent of GFR.

Management

Most patients with evidence of CKD are managed by a nephrologist, with referral once GFR is sustained below 30 mL/minute/1.73 m². In addition, evidence of the sequelae of CKD should also prompt referral, for instance, refractory hypertension, persistent electrolyte abnormalities, as well as consistent evidence of albuminuria. Management is often focused on slowing the progression of disease. Hypertension management tends to be more robust in those with CKD and tends to include the use of an ACEi or ARB. Diabetic management focuses on reducing HbA1c, whilst lipid management is also important. Avoidance of nephrotoxic medications also plays a part. Renal replacement therapy is considered for appropriate patients once GFR is 5-10 mL/minute/1.73 m²

References

• Denker B, Aird W. Overview of Chronic Kidney Disease in Adults. In DynaMed, EBSCO Information Services. Accessed September 27, 2023. https://www.dynamed.com/condition/overview-of-chronic-kidney-disease-ckd-in-adults/about
• Levey A, Inker L, Curhan G, Forman J. Definition and staging of chronic kidney disease in adults. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Accessed September 27, 2023. https://pro.uptodatefree.ir/show/16406