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Chronic Renal Disease (CRD), Chronic Kidney Disease (CKD) Print E-mail

Dr. Kennedy Chronic renal disease (CRD), also known as chronic kidney disease (CKD), is a progressive loss of renal function over a period of months or years and is tracked by doctors in five stages. Each stage progresses through declining glomerular filtration rate (GFR), which is usually determined indirectly by the creatinine level in blood serum or more specifically by the 24 hour urine output of creatinine.

Initially CRD is asymptomatic and is detected as an increase in serum creatinine or protein in the urine. As the kidney function decreases:

  • Blood pressure is increased due to fluid overload and production of vasoactive hormones leading to hypertension and congestive heart failure
  • Urea accumulates, leading to azotemia and ultimately uremia (symptoms ranging from lethargy to pericarditis and encephalopathy). Urea is excreted by sweating and crystallizes on skin ("uremic frost").
  • Potassium accumulates in the blood (known as hyperkalemia with symptoms ranging from malaise to fatal cardiac arrhythmias)
  • Erythropoietin synthesis is decreased (leading to anemia causing fatigue)
  • Fluid volume overload - symptoms may range from mild edema to life-threatening pulmonary edema
  • Hyperphosphatemia - due to reduced phosphate excretion, associated with hypocalcemia (due to vitamin D3 deficiency). Later this progresses to tertiary hyperparathyroidism, with hypercalcaemia, renal osteodystrophy and vascular calcification
  • Metabolic acidosis, due to decreased excretion of acid by the kidney. This may causes altered enzyme activity by excess acid acting on enzymes and also increased excitability of cardiac and neuronal membranes by the promotion of hyperkalemia due to excess acid (acidemia) [2]
  • Onset of acelerated atherosclerosis with higher incidence of cardiovascular disease and a worse prognosis than those who do not have CRD.

The size of the kidneys are measured using abdominal ultrasound and in CRD the Kidneys are usually smaller (less than 9 cm) than normal kidneys. There are exceptions such as in diabetic nephropathy and polycystic kidney disease in which the kidneys may be normal in size. A diagnostic clue that helps differentiate CRD from acute renal failure (ARF) is a gradual rise in serum creatinine (over several months or years) as opposed to a sudden increase in the serum creatinine (several days to weeks). If these levels are unavailable (because the patient has been well and has had no blood tests) it is occasionally necessary to treat a patient briefly as having ARF until it has been established that the renal impairment is irreversible.

Numerous uremic toxins accumulate in chronic renal failure when it is treated with standard dialysis. These toxic protein bound substances are of interest to medical scientists interested in improving the standard chronic dialysis procedures used today.

All individuals with a Glomerular filtration rate (GFR) <60 mL/min/1.73 m2 for 3 months are classified as having chronic kidney disease, irrespective of the presence or absence of kidney damage. Reduction in kidney function to this level or lower represents loss of at least one-half the adult level of normal kidney function, and may be associated with a number of complications.

All individuals with kidney damage are classified as having chronic kidney disease, regardless of the level of GFR. The reason for including individuals with and adequate GFR 60 mL/min/1.73 m2, but who have actual damage, is that GFR may be sustained at normal or increased levels despite substantial kidney damage and that patients with kidney damage are at increased risk of the two major outcomes of chronic kidney disease: loss of kidney function and development of cardiovascular disease.

Stages of Chronic Renal Disease

  • Stage 1: Slightly diminished function; Kidney damage with normal or increased GFR (>90 mL/min/1.73 m2). Kidney damage is defined as pathologic abnormalities or markers of damage, including abnormalities in blood or urine test or imaging studies.[5]
  • Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m2) with kidney damage. Kidney damage is defined as pathologic abnormalities or markers of damage, including abnormalities in blood or urine test or imaging studies.
  • Stage 3: Moderate reduction in GFR (30-59 mL/min/1.73 m2)
  • Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m2)
  • Stage 5: Established kidney failure (GFR <15 mL/min/1.73 m2, or permanent renal replacement therapy (RRT)

    The most common causes of CKD are diabetic nephropathy, hypertension, and glomerulonephritis. Together, these cause approximately 75% of all adult cases. Certain geographic areas have a high incidence of HIV nephropathy.


  • The goal of therapy is to slow down or halt the otherwise relentless progression of CRD to stage 5. Control of blood pressure and treatment of the original disease, whenever possible, are the broad principles of management. Generally, angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II receptor antagonists (ARBs) are used, as they have been found to slow the progression of CRD to stage 5.
  • Replacement of erythropoietin and vitamin D3, two hormones processed by the kidney, is usually necessary, as is calcium. Phosphate binders are used to control the serum phosphate levels, which are usually elevated in chronic kidney disease.
  • When one reaches stage 5 CKD, renal replacement therapy is required, in the form of either dialysis or a transplant.

  • The information in this article is not meant to be medical advice.�Treatment for a medical condition should come at the recommendation of your personal physician.

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