General | June 21, 2015 | Author: The Super Pharmacist
One major distinction among people with kidney disease is determining if the illness is acute or chronic. Acute renal failure is a kidney disturbance, either rising creatinine levels in the blood, markedly decreased urine output, or an abnormal urinalysis, that occurs over a short period (e.g. less than 48 hours). Chronic renal disease is a slow, progressive deterioration in kidney function lasting for at least three months. The causes of acute and chronic renal disease are largely separate from one another. Likewise, many causes of acute renal failure are reversible while chronic renal disease can rarely be stopped. At best, most people with chronic renal disease can hope to slow the progression of the illness (or avoid it before it starts). The “stages of renal disease” refer to chronic kidney disease rather than acute causes.
The healthy kidney filters 20% of the blood volume at any given moment. Nutrients such as glucose are retained in the bloodstream, while wastes such as urea are excreted. Physicians can determine the health of the kidney by measuring how well the kidney is doing this job. Kidney function (and consequently the health of the kidney) is estimated in two ways:
1. Glomerular filtration rate: The kidney’s ability to filter the blood of creatinine
2. Albuminuria: The amount of the protein, albumin, in the urine
If creatinine levels rise in the blood, it indicates that the kidney is not working properly. The higher the creatinine levels, the worse the renal disease, for the most part. Under normal circumstances there should be very little or no albumin in the urine. As kidney disease progresses, the amount of albumin in the urine will increase.
Based on these two simple tests, a blood test and a urine test, physicians can classify patients with chronic kidney disease into one of several stages. Physicians use of these stages to guide treatment decisions and evaluate risk and prognosis. These stages can be used to determine how many clinical appointments with kidney function monitoring are required per year. On average, the greater the number of visits required per year, the higher the risk of kidney and cardiovascular complications.
While physicians have 18 separate categories in which to place people with chronic renal disease, the system is far from perfect. For example, someone with a GFR of 16 has far worse kidney function than someone with a GFR of 29, yet they are both the GFR stage 4. Therefore, it is important to consider these classifications in the context of the patient's primary kidney disease. Moreover, complications of chronic renal disease can occur at any time and within any of these GFR or albumin stages (though the they become more likely as the disease progresses at later stages).
The main complications of chronic renal disease affect the kidney itself, the cardiovascular system, and endocrine/metabolic function. The risk of these complications (all-cause mortality, cardiovascular mortality, and kidney failure) increases as the stage of renal disease increases.
Over time, kidney function generally worsens until the patient with chronic kidney disease eventually enters end-stage renal disease and kidney failure. At this point, dialysis or kidney transplantation are the only viable options. But before this point, the kidney may experience increasing levels of damage to its filtration mechanism. This progression can be slowed to some degree by controlling blood pressure, avoiding aggressive treatment of diabetes mellitus, and the use of ACE inhibitors or angiotensin-receptor blockers (ARBs) are limited. There is also some evidence to suggest that protein restriction, smoking cessation, statins therapy, and supplemental treatment with bicarbonate may help protect the kidneys.
High blood pressure is extremely common in people with chronic renal disease. Destructive changes in the kidney also may make it more difficult to control high blood pressure. As the disease progresses to stages G4 and G5, the balance of fluid and sodium in the blood is compromised. Potassium also increases substantially as the renal disease progresses. In fact, elevated potassium can cause serious, sometimes fatal, rhythm disturbances in the heart. Abnormal cholesterol levels and anemia are quite common, especially as the disease progresses.
Patients with chronic kidney disease have multiple problems with hormones and metabolism. Phosphate levels tend to increase as kidney function decreases. Phosphate and calcium levels are working to counterbalance each other. Therefore, as phosphate levels begin to rise, more calcium is extracted from the bones, which leads to osteoporosis and other calcium related issues. Increasing calcium consumption to counteract this effect is not always the best treatment option. While increased calcium will reduce phosphate levels, it will also cause too much calcium to circulate in the blood, which can cause its own problems. Thus, drugs that bind phosphate may be the better treatment option. A healthy kidney plays an important role in thyroid metabolism. Consequently, when the kidney becomes dysfunctional in chronic renal disease, circulating thyroid hormone levels are disrupted. Hypothyroidism, specifically, occurs with high frequency among people with chronic kidney disease. Hypothyroidism can be treated with synthetic thyroid hormones. Many people with late stage chronic kidney disease experience malnutrition. This may be due to a decrease desire to eat, less nutrition being absorbed by the gastrointestinal tract, and metabolic acidosis. Malnutrition can lead to a whole host of problems, especially in people with chronic renal disease. Therefore, affected individuals must work closely with healthcare professionals to prevent or promptly treat nutritional deficits.
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