I wish that saints would cling to Christ half as earnestly as sinners cling to the devil. If we were as willing to suffer for God as some are willing to suffer for their lusts, what perseverance and zeal would be seen on all sides!
C.H. Spurgeon

Kidney Failure

Kidney Failure

KIDNEY FAILURE

The term kidney failure is very broad, and refers to the loss of those functions which are necessary for normal existence. As a rule there is ample reserve capacity present in the kidneys such that even removal of one entire kidney and part of the other will cause no demonstrable abnormality in metabolism, except in specially designed tests. Thus for imbalances to occur, there is usually some disorder affecting both kidneys at the same time.

A condensed description of the function of the kidneys is that they are responsible for the regulation of certain chemicals in the body fluids; by selectively secreting or keeping varying amount of these substances in the urine, a very delicate and complex balance is maintained. The substances in question include water, sodium, potassium, acid byproducts of metabolism, drugs, calcium, magnesium, uric acid, and hundreds of others. The blood carries the ingested and metabolically produced substances to the kidneys, which then filters them and “chooses” how much of each should remain or be secreted into the urine. Hormones, concentration gradients, blood flow, and other factors all play a role in this elegant scheme.

Kidney failure may be either acute or chronic. It is a general rule that chronic renal (kidney) failure is irreversible in most cases, whereas acute failure may be sometimes reversible, and other times lead to chronic kidney failure.

CAUSES OF ACUTE KIDNEY FAILURE

Loss of blood supply to the kidneys through bleeding, drop in the blood pressure from shock of any cause, congestive heart failure, or other factors.

Toxins including carbon tetrachloride, certain mushrooms, illicit drugs, antifreeze,
medications, allergic reactions.

Sudden breakdown in muscle tissue as after marathon running or injury, releasing a chemical myoglobin which can damage kidneys.

This list is not comprehensive, but attests to the wide variety of potential damaging factors which are commonly seen.

CAUSES OF CHRONIC KIDNEY FAILURE High Blood Pressure

Chronic kidney infection.

Diabetes, where the small blood vessels of the kidney are damaged.

Lupus and other immune diseases where the kidneys are involved.

Certain drugs and toxins.

Glomerulonephritis (see nephritis section).

The list is not comprehensive, and many cases of chronic renal failure are never found to have a clear cause. It seems that in the end stage, the various causes yield the same basic abnormalities, and the final approach is quite similar.

SYMPTOMS AND MECHANISMS

The first symptoms of kidney failure are due to accumulation in the blood of excess amounts of certain chemicals, often urea. Fatigue, nausea or vomiting, weight loss, muscle cramps are common. Irregular heart rhythms may result from imbalances in potassium and other chemicals. The formation of red blood cells and the function of platelets are dependent on certain kidney functions, and anemia and abnormal blood clotting are sometimes seen. Virtually any symptom and organ system can be affected, given the widespread duties of the kidneys. Once the abnormalities become profound, death may occur from excessive fluid retention, chemical imbalance which the heart cannot tolerate, or coma due to the toxic effects of accumulated metabolic byproducts on the brain.

DIAGNOSIS

Due to the diffuse nature of the symptoms of kidney failure, the precise diagnosis depends upon the laboratory data, which is done when symptoms persist in the appropriate setting. A typical combination of common laboratory abnormalities would include an abnormal urinalysis, elevated blood potassium, decreased calcium, low blood count, and elevation of two chemicals called creatinine and urea nitrogen. The last two are considered to be the most closely related to actual kidney function. Precise estimates are further obtained by analyzing 24 hour urine specimens.

TREATMENT

The therapy of specific underlying diseases is beyond the scope of this discussion, but clearly the reversible elements must be actively sought and addressed. Therapy specific to the kidney failure are divided into dialysis and other forms of treatment.

NON-DIALYSIS TREATMENT

Dietary restriction of such things as protein, salt, total fluid, and potassium. A very precise and highly regulated regimen must be worked out for each patient individually, and rigid adherence may improve symptoms and delay or even prevent the need for further measures. Many drugs are excreted through the kidneys, and all medications should be carefully assessed as dosage adjustments are often necessary. Vitamin D can sometimes be useful to reduce the bone weakening which sometimes accompanies kidney failure. High blood pressure either as a pre-disposing disease or secondary to the kidney failure (through excessive fluid retention or hormone imbalances) should be carefully treated. Specific drugs for nausea or itching can be quite helpful. Diuretics used selectively can help to increase fluid excretion when this is a problem.

DIALYSIS

Dialysis refers to the artificial filtering of blood in the hopes of replacing the filtering functions of the kidneys. It is an expensive and complex undertaking, requiring total patient commitment, family involvement, and an intense patient-physician relationship. Patients must be carefully chosen both from those standpoints, as well as from a medical perspective; those with underlying diseases which carry a poor prognosis may not benefit from dialysis, since the underlying disease may prove fatal at any rate.

There are two major forms of dialysis in common use at this time, hemodialysis and peritoneal dialysis. Hemodialysis–this procedure requires that a small artificial shunt be surgically inserted between an artery and a vein through a small operation. Then, several times a week, the patient’s blood is pumped from the shunt through an artificial kidney machine which uses certain filtering techniques to bring the vital chemicals back into balance. This may take many hours, and obviously presents a major burden on the patient and family. For this reason there has been increasing emphasis on providing this service in clinics and even at home, when the patient, family, and supporting medical resources can all be arranged.

The patient on dialysis is not free of disease or complications, and these include infection, neurologic, and cardiac problems. Psychologic reactions to the sort of existence this requires can be major. Very close medical follow-up remains necessary. The mortality of patients on chronic hemodialysis range from 2 to 10% yearly; it must be recalled that these are patients who would likely have died imminently of their kidney failure without treatment.

PERITONEAL DIALYSIS

The lining of the abdominal cavity has been found to have many of the filtering properties for blood that are performed in the normal kidneys. If fluid containing carefully calculated amounts of chemicals is present on one side of the lining, the blood which circulates in and around the lining (peritoneum) will equilibrate its chemical balance with that of the fluid. This process is called peritoneal dialysis.

After the surgical insertion of a special tube through the abdominal wall, dialysis fluid is instilled into the abdomen and allowed to remain there for several hours. It is then drained out and replaced with fresh fluid. By choosing the type of fluid, the blood chemicals can be regulated in this manner. While the fluid is waiting to equilibrate the patient is free to go about normal activities. Exchanges are made 4 or 5 times daily in many cases.

Not all patients can do well with peritoneal dialysis, and complications such as intra- abdominal infections are common. It does provide freedom from the “machine” of hemodialysis, is largely manageable by the patient with careful medical supervision, and is quite suitable for many patients.

KIDNEY TRANSPLANT SURGERY

It is clear that dialysis is not an easy treatment even at best. For this reason, many patients on dialysis are considered for receipt of transplanted kidneys from either a live donor, or a recently deceased donor whose kidneys have been carefully preserved.

Aside from the surgical problems involved, the transplanted kidneys may fail for reasons of rejection by the body. In the case of identical twin donors, up to 90% of transplants succeed after three years. With other related donors, up to 3/4 are functioning at three years, and in cadaver transplants, about 60% remain. Successful transplantation requires the institution of anti-rejection drugs, and complicated follow-up programs. Immunosuppressive drugs such as prednisone, azothioprine and others leave the patient vulnerable to infections of many varieties. The newer drug cyclosporine has improved this picture, and active research may bring even further progress in this important area. Many patients have to revert to dialysis after a transplant fails, but still others undergo second or even third transplants.

SUMMARY

Kidney failure is a major national health problem against which major progress has been made in the past 10 years. The financial, medical, psychological, and societal problems associated with it are profound, and patients are generally under virtually constant medical supervision. The most promising areas of future progress seem to be in the areas of prevention of transplant rejection and newer programs of maintenance dialysis.