Renal failure vying for No. 1 killer spot

by Dr. I.W.M. Upul Bandara Ilangasingha

Chronic renal failure is a condition in which the kidney function gradually declines until the kidneys are unable to filter wastes from the body; maintain the proper balance of water and chemicals such as sodium and potassium in the blood stream or produce urine.

Chronic kidney disease (CRF) can occur in anyone with an illness or injury that affects the kidneys. Diabetes mellitus is one of the commonest causes of chronic renal failure.

As a complication of uncontrolled diabetes mellitus (insulin dependant or non-insulin dependant) for a longer period may affect the microvasculature of the kidney leading to persistent proteinuria. This condition is known as diabetic nephropathy.

Virtually all the diabetic nephropathy patients' eyes too get affected for which if not treated promptly, may lead to blindness. In advanced renal disease, retinopathy is usually severe with new vessel formations. As the renal failure progresses, the development of uraemia in diabetic patients is associated with number of other complications.

Fluid retention and oedema (collection of fluid, specially in the ankles; face;) occur relatively early in the development of renal failure. As the disease progresses further, fluids starts to get collected in the lungs.

This is known as pulmonary oedema and prognosis at this stage is poor. Peripheral neuropathy is another complication of long standing diabetics with renal involvement.

Numbness of the toes is a early sign of this condition. They are more prone to get foot infections leading to amputations as a result of a combination of neuropathy and arterial blood vessels.

Disturbances of lipid metabolism of diabetes and kidney disease together with hypertension may contribute to the formation of sclerotic changes of the blood vessels. Coronary artery disease is one of the major cause of death in these patients.

Renal vascular disease or uncontrolled hypertension is anther common cause of renal failure. Many primary kidney diseases lead to the development of hypertension. When kidneys being affected due to some reason, and if the blood pressure is not controlled, it will act in favour of damaging the microvasculature of the kidney in various means helping to progress in to renal failure.

For a patient with a history of renal disease the ideal blood pressure is accepted as 110/70 - 120/70 mm Hg. Blood pressures beyond this level, accelerate of decline of renal functions.

Toxic nephropathy is another common cause which causes renal failure. Long-term consumption of pain killers is a recognized cause for this. Specially the middle aged and elderly age groups are at a higher risk. Aluminium toxicity has been identified as another major contributory factor for renal failure. By using aluminium vessels for cooking purposes, the risk of aluminium particles getting in to the body remains at a higher level.

Other causes of renal failure includes polycystic kidney disease; renal stones; cancers and autoimmune disorders such as systemic lupus erythematosus (SLE).

Chronic renal failure is a condition which will progress gradually over a long period. Therefore patients will not notice any acute symptoms. As the time passes, when the glomerule filtration rate (GFR) declines, waste products and fluids starts to get collected in the blood stream.

This excess fluid causes swelling of the body; specially in the feet, face and abdomen. In parallel the blood pressure starts to increase. As the GFR drops, urine output will start to decrease and patients will start feeling nausea/ fatigue and itching of the body. As the disease progresses, foul smelling breath, confusion and seizures can occur due to uraemic toxicity.

Cardio-vascular disease accounts for more than 50% of overall mortality and morbidity of patients with end stage renal disease. When diabetes mellitus is present, the mortality rate is three fold higher than that in patients with other causes of end stage renal disease.

Increased total serum cholesterol, high blood pressure; and smoking are major risk factors for coronary artery disease. Lowering of total and low density lipoprotein cholesterol reduces the risk of coronary artery disease.

Myocardial infarction is the cause of death in many patients with renal failure.

If coronary heart disease is already present, a particular effort should be made to prevent overhydration as this will reduce the dilatation of heart chambers and parallely the demand for oxygen by the heart muscles also will reduce.

As a result, the ischemic attacks which may present as chest pain due to an imbalance between the oxygen demand of the heart muscles and oxygen supply may reduce. This imbalance can be either due to an absolute reduction in the blood flow to the heart muscles as a result of occlusions in the blood vessels; due to an increase in the oxygen requirement by the heart muscles or due to an inadequate oxygen carrying capacity of the blood, which is known as anaemia.

Anaemia is another complication of renal failure. Majority of patients with renal failure develop anaemia which increases in severity as renal function deteriorates. For the normal production of red blood cells requires a number of essential factors, including iron; folate; (Folic acid), vitamin B 12 and a hormone called erythropoietin; which is secreted by the kidneys.

Any damage to the kidneys will cause a reduction in the synthesis of the hormone. This is a major reason for anaemia in renal failure. With the introduction of recombinant human erythropoietin, the necessity of blood transfusions has become less.

After the commencement of haemodialysis, for such patients when erythropoietin injection is given, the severity of anaemia improves. Nevertheless, a minority of patients become blood transfusion dependent and require intermittent blood transfusions. As the renal failure progresses; due to the toxic effects of uraemia; platelet dysfunctions can occur causing bleeding disorders.

Early initiation of haemodialysis prevents the development of transfusion dependence. Frequent blood transfusions can cause suppression of the activity of red cell production. Therefore red cell transfusion should be reserved for symptomatic anaemia.

Also frequent blood transfusions increases the risk of iron overload and blood borne infections, such as Hepatitis-B; HIV, and Malaria. Specially, blood transfusions should be avoided in patients who are awaiting a kidney transplant, as there is a risk of antibody production to the HLA antigens and hence reducing the changes of receiving a successful transplantation.

Sudden decline in renal factions in chronic renal failure patients can occur mainly due to 3 reasons.

1. Volume depletion: Which can be due to dehydration as a result of poor fluid intake or infections which cause diarrhoea and vomiting. Ideally, patients with chronic renal failure should be volume expanded as suggested by the presence of a small amount of pedal oedema.

2. Depression of cardiac output such as congestive heart failure: over control of blood pressure. Therefore treatment that increases cardiac output may improve renal functions.

3. Drugs which cause direct toxicity to renal structure of decrease renal perfusion. This is very important when using pain-killers. CRF patients should not use NSAIDS as pain killers, as they decreases the renal perfusion.

Proper conservative medical treatment may postpone the need for dialysis. As a conservative management of end stage renal disease; dietary modifications are very important for slowing progression of renal failure. The diet should be a low protein diet with high biologic value proteins. That is animal proteins.

The purpose of reducing protein intake is to minimise the accumulation of nitrogenous waste products. No salt-added diet should be adequate. Daily salt intake should be 8g/day. High potassium food such as banana/king coconut/avocado/dried fruits such as nuts, prunes, sulthana/komadu/greeneries and citrus fruits should be avoided.

So ideally a CRF diet should be a low calorie (35-50 Cal/Kg). Low protein (0.6-0.7 g/Kg) low fat; low salt; low potassium diet. High cholesterol, hypertension and anaemia should be corrected promptly with medication. To avoid renal borne disease (Renal osteodystrophy) the serum calcium and phosphorus levels must be checked and corrected.

All patients with kidney failure should be monitored for intake and output of fluids, so treatment and medication can be adjusted as necessary. In severe cases; patients, will need dialysis, a procedure in which waste products are filtered from the blood with the help of a machine or will need a kidney transplant.