Renal failure, or when the kidneys fail to function properly, can be physiologically described as a decrease in the rate at which the glomerulus, a tiny structure in the kidney, filters blood to form urine. Kidney failure can generally be classified as chronic, acute, and acute on chronic renal failure.
The type of renal failure is determined by the trend in the serum creatinine, a widely used blood-chemistry test to assess renal function. Deficient filtration by the kidneys causes the levels of creatinine, a metabolic waste found in blood and muscles, to rise. Serum creatinine levels, however, are also affected by a patient’s existing muscle mass, which varies with age, race, and sex, potentially leading to inaccurate diagnoses. Better tests are available, but they are significantly costlier and not as widely applicable.
Other factors that may help differentiate acute and chronic renal failure include the kidney size and the presence of anemia. Chronic renal failure generally leads to a small kidney size detected on ultrasound and anemia.
According to the Centers for Disease Control and Prevention’s (CDC) National Center for Chronic Disease Prevention and Health Promotion, the US incidence of chronic kidney disease in people ages 20 or older has risen 16.8 percent from 1999 to 2004. But not only is the incidence of chronic kidney disease increasing, the rate of increase itself appears to be rising over time. The prevalence of chronic kidney disease is greater among older people, Mexican-Americans, non-Hispanic blacks and among those with diabetes, hypertension, and cardiovascular disease.
Chronic renal failure develops slowly and displays few initial symptoms. It can result as a complication of a number of kidney diseases including:
- IgA nephritis, Berger’s disease, or synpharyngitic glomerulonephritis – inflammation of the glomeruli (small blood vessels) of the kidney characterized by deposition of the IgA antibody in the glomerulus
- Glomerulonephritis – primary or secondary immune-mediated renal disease characterized by inflammation of the glomeruli
- Chronic pyelonephritis – inflammation of the kidney and upper urinary tract that most often results from a non-contagious bacterial infection of the bladder
- Urinary retention
The ultimate consequence of chronic renal failure is end-stage renal failure (ESRF). Those with ESRF usually require a dialysis until a renal transplant donor is found. Both patients with ESRF and their physicians also need to be aware that Magnetic Resonance Imaging (MRI) and/or Magnetic Resonance Angiography (MRA) scans with a gadolinium-based contrast agent may put the patient at risk for developing Nephrogenic Systemic Fibrosis (NSF/NFD), a serious condition in which the skin hardens and thickens at times to the point where it becomes difficult to move.
Acute renal failure is a rapid loss of renal function characterized by a decrease in urine production, body fluid disturbances, and electrolyte derangement. Dialysis may be necessary until the underlying cause is identified so it can be treated. Symptoms to look out for include:
- Dark urine
- Weight gain
- Joint pain
- Kidney pain
One potential cause of acute renal failure is rhabdomyolysis, a breakdown of muscle fibers that releases some of the fibers into the blood stream, some of which are toxic. A group of medications known as statins, which include Crestor and Baycol, have been shown in some cases to cause rhabdomyolysis. Another group of drugs known as COX-2 inhibitors is also associated with kidney damage. COX-2 inhibitor drugs include Vioxx, Celebrex and Bextra.
People already with chronic renal failure can also develop acute renal failure. This condition is known as acute-on-chronic renal failure (AoCRF). The aim of treatment is to reverse the acute part of the condition, thereby returning the patient to his or her baseline renal function. Distinguishing AoCRF from chronic renal failure is particularly difficult in patients that were not previously monitored and for which no baseline blood work is available to their physician.