Chronic kidney disease (CKD) is a dreaded disease for which medical science has no remedy. CKD is increasing at an alarming rate all over the world. One in ten persons has some form of chronic kidney disease. Rising prevalence of diabetes, hypertension, obesity, smoking, and high cholesterol is major reason for increasing incidences of CKD.
CKD occurs when the kidneys become damaged and gradually unable to perform their functions. With treatment, the kidney function may remain stable, but if not, the damage becomes worse over months to years. The serum creatinine levels rise gradually and the level of kidney function (also called the glomerular filtration rate or GFR) can be calculated from this blood test. The stage CKD can thus be graded as mild, moderate or severe. The presence of albumin in the urine also indicates that kidney damage is present (see tables stage of chronic kidney disease). CKD was previously called Chronic Renal Failure (CRF) but the word failure gives a wrong impression. In early CKD, there is still some degree of renal function and only in the late stages where kidney failure truly occur.
End-stage kidney disease (ESKD) or end-stage renal disease (ESRD) refers to the time when CKD reaches an advanced stage (less than 10% of normal function). The kidneys may even fail completely and the condition is irreversible.
At this point, conservative management (i.e. medications, diet, lifestyle modifications) is not sufficient to maintain life and renal replacement therapy (dialysis or kidney transplantation) is required.
In chronic kidney disease (CKD), kidney function gradually declines over months to years. In the early stages of CKD, most patients remain relatively without symptoms as their bodies compensate and get used to the metabolic derangements that develop over time. When the kidney function becomes severely impaired, symptoms due to the accumulation of toxins and fluids start to develop.
Symptoms of CKD vary depending on the severity of the kidney damage. CKD is divided into five stages based on the level of kidney function or glomerular filtration rate (GFR). GFR can be estimated from blood levels of creatinine and is normally greater than 90 ml/min.
In Stage 1 CKD, the GFR is greater than 90 ml/min/1.73m2 but there are laboratory abnormalities like protein in the urine; evidence of structural damage to the kidneys on x-ray, ultrasound, MRI, or CT scan; or a family history of polycystic kidney disease. Patients are usually asymptomatic.
In Stage 2 or mild CKD, the GFR is 60 – 89 ml/min/1.73m2 . Patients are usually asymptomatic but some may complain of frequent urination especially at night, high BP, urine abnormalities on urinalysis with normal or slightly high serum creatinine.
In Stage 3 or moderate CKD, the GFR is 30-59 ml/min/1.73m2. The patient may still be asymptomatic or start having mild symptoms. There may be urinary abnormalities present and serum creatinine is elevated.
In Stage 4 CKD, GFR is 15-29 ml/min/1.73m2. Symptoms may be mild, vague and nonspecific, or very severe, depending on the underlying cause of kidney failure and associated illnesses.
Stage 5 is very severe CKD with GFR of < 15 ml/min/1.73m2. Also called End Stage Kidney Disease, most patients will need dialysis or kidney transplantation at this stage. Symptoms may vary from moderate to severe, with life-threatening complications.
In persons with high blood pressure (hypertension) suspect CKD if:
Potential complications of advanced CKD are:
CKD is commonly asymptomatic in early stages. Usually, CKD is initially diagnosed when hypertension is detected, a blood test showing elevated serum creatinine is requested or urine tests positive for albumin. A person must be screened for CKD if he is at high risk for developing kidney damage (diabetic, hypertensive, older age, family history of CKD).
Haemoglobin levels are usually low. Anaemia is due to decreased erythropoietin production by the kidney.
Albumin or Protein in the urine (called albuminuria or proteinuria) is an early sign of CKD. Even small amounts of albumin in the urine, called microalbuminuria, may be the earliest sign of CKD. Since proteinuria can be also due to fever or heavy exercise, it is best to exclude other causes of proteinuria before diagnosing CKD.
An easy and inexpensive way to measure kidney function is a blood level of creatinine. Together with age and sex, the serum creatinine is used in many formulas to estimate kidney function or glomerular filtration rate (eGFR). Regular monitoring of creatinine helps to assess progression and treatment response in CKD. On the basis of eGFR, CKD is divided into five stages. This staging is useful to recommend additional testing and suggestions for proper management.
The ultrasound is a simple, effective and inexpensive test in the diagnosis of CKD. Shrunken kidneys are diagnostic of chronic kidney disease. However, normal or even large kidneys are seen in CKD caused by adult polycystic kidney disease, diabetic nephropathy and amyloidosis. Ultrasound is also helpful to diagnose CKD due to urinary obstruction or kidney stones.
CKD causes disturbances in different functions of the kidneys. To evaluate these disturbances different tests are performed such as: tests for electrolyte and acid-base balance (sodium, potassium, magnesium, bicarbonate), tests for anaemia (haematocrit, ferritin, transferrin saturation, peripheral smear), tests for bone disease (calcium, phosphorus, alkaline phosphatase, parathyroid hormone), other general tests (serum albumin, cholesterol, triglycerides, blood glucose and haemoglobin A1c) and ECG and echocardiography.
Patients with CKD should contact the doctor immediately, if he or she develops: