An important function of the kidney is to excrete waste products by (glomerular) filtration and / or secretion. The kidney function is estimated by calculating the glomerular filtration rate (eGFR). The eGFR is calculated with the CKD-EPI formula which includes sex, age, body size and the level of circulating creatinine. The renal function shows a physiologic decline with increasing age. Chronic renal failure (CRF) is defined by a persisting (more than three months) decrease of the glomerular filtration rate (eGFR <60 ml/min/1,73m2) and / or albuminuria (albumin / creatinine ratio >3 mg/mmol) and / or abnormalities in the urinary sediment (e.g. dysmorphic erythrocytes or erythrocyte cylinders).
Clinical symptoms of chronic renal failure may occur in more severe cases of renal failure and are not frequently seen in general practice. In CRF with an eGFR below 30 ml/min/1,73m2 patients may present with metabolic complications such as anaemia, itch, gout, acidosis and gastrointestinal symptoms (e.g. nausea, decreased appetite).
Common causes of CRF are hypertension, type 2 diabetes mellitus, and atherosclerotic vascular disease. Specific (familiar) renal diseases may also cause CRF.
A decreased eGFR and increased albuminuria are independent risk factors and predictors in themselves of (cardiovascular) mortality, the (acute) progression of CRF and of end stage renal failure (eGFR <15 ml/min/1,73m2).
In the diagnosing and staging of CRF, the GP assesses the eGFR, the albumin-creatinine ratio in the urine, and the cardiovascular risk profile. Treatment consists of optimising the cardiovascular risk profile and reducing the risk of progression of CRF. RAS-inhibitors are the preferred antihypertensives in the case of albuminuria. Nephrotoxic medication is best avoided. To support safe prescribing in patients with CRF, an alert should be created in the Electronic Health Record that CRF is present, so that medication monitoring systems can warn for nephrotoxic medication or when medication dosage needs to be adjusted.