Diseases of Kidney and Urinary Tract (4 Diseases)

The following points highlight the four main diseases of kidney and urinary tract. The diseases are: 1. Acute Glomerulonephritis 2. Nephrotic Syndrome 3. Acute Renal Failure 4. Chronic Renal Failure (Uremia).

Disease # 1. Acute Glomerulonephritis:

This is characterized by acute inflammation of the glomeruli with congestion. Renal blood flow and glomerular filtration rate are reduced by 50 per cent. The urine volume falls and sodium excretion is greatly reduced. The urine contains moderate amounts of protein, red and white cells in abun­dance and casts of the renal tubules formed by pre­cipitation of protein and red cells in the tubular system.

When the patient continues to ingest normal quantities of sodium and water, oedema develops and the blood pressure rises leading to headaches and swelling of the face and hands in the morning and of the ankles at night.

Treatment:

Fluid intake should be restricted to 500 ml daily. During the first few days of treatment, the fluid given should be less. Sodium intake can be relaxed when oedema resolves and the blood pressure falls. Protein is restricted only when the blood urea is raised.

Disease # 2. Nephrotic Syndrome:

This is characterised by heavy proteinuria, hypoalbuminaemia and peripheral oedema. It oc­curs when glomerular capillaries are damaged re­sulting in the increased losses of plasma proteins from the body into the urine. This syndrome can arise in diabetes mellitus, amyloidosis, multiple myeloma.

Treatment:

Salt should not be added at table and only small quantities should be added during cooking. Fresh meat and fish can be used to supplement the pro­tein intake. Egg can be used freely but cheese should be reserved for special occasions.

Disease # 3. Acute Renal Failure:

This is a catastrophic event.

The causes are:

(a) Loss of blood from any cause including complications of pregnancy, trauma or gastrointestinal bleeding.

(b) Loss of plasma as in burns and crush inju­ries.

(c) Loss of fluid from severe vomiting, diar­rhoea, acute intestinal obstruction.

(d) Serious infections especially septicaemia.

(e) Acute haemolytic disorders.

Treatment:

Protein intake should be reduced. A daily intake of 100 grams of sugar has a marked protein-sparing effect. If the patient is vomiting, dextrose in water has to be given intravenously. The diet should con­tain potassium chloride by mouth.

Disease # 4. Chronic Renal Failure (Uremia):

Uremia is a term used to describe general renal fail­ure from any cause. As a result, many complex bio­chemical changes occur which are more responsi­ble for the clinical features than the elevation of blood urea. These changes include disturbances in hydrogen ion concentration and abnormalities in water and electrolyte balance.

Clinical Features:

(a) The failing kidney is unable to compen­sate for large fluctuations in salt intake and for other increased metabolic de­mands.

(b) Uncompensated losses of water and so­dium result in dehydration and salt deple­tion, with a fall in plasma volume, arterial blood pressure, renal blood flow and glomerular filtration rate.

(c) Renal function is lost and mild renal fail­ure progresses to severe uremia.

(d) Tiredness, breathlessness on exertion may arise from anemia. A tendency to bleed due to abnormal platelet function.

(e) Anorexia, nausea and vomiting may re­sult from the accumulation of urea, creati­nine or an unknown uremic toxin. When GFR falls below 5 ml/min the kidneys may be unable to excrete even normal quanti­ties of sodium and water. Many patients at this stage develop hypertension, oedema and features of water intoxication.

(f) The execution of hydrogen ions is im­paired, the plasma bicarbonate concentra­tion falls and an observer may notice com­pensatory hyperventilation of which the patient is often unaware.

(g) In the final stages death can result from hypertension, uremic coma, pulmonary oedema, gastrointestinal haemorrhage, hyperkalemia or severe infection.

Treatment:

(a) In mild cases, active steps should be taken to control hypertension, to correct salt and water imbalance and to treat active uri­nary tract infection. Fluids and electrolytes should be given intravenously. A high protein diet is usually indicated in neph­rotic patients with excessive losses of pro­tein in the urine.

Sodium restriction may be necessary in some patients, but others may need extra salt to compensate for uri­nary losses. Sodium bicarbonate may be needed for treatment of acidosis.

(b) Vitamin D can be used for the treatment and prevention of metabolic bone disease. Increase in plasma calcium may damage the kidney and accelerate loss of renal function.

(c) As renal failure progresses and the patient develops symptoms of uremia, more ac­tive measures are necessary to compen­sate for the loss of renal function. Patients may be treated by dietetic measures alone, by regular hemodialysis or by renal trans­plantation.

Stones in the Urinary Tract:

Stones may form in the bladder (vesical calculi) or the kidney (renal calculi) 95 per cent of stones are made up of calcium salts. About 3 per cent are uric acid salts and about 1 per cent are cystine. Most stones are a mixture of calcium oxalate, calcium phosphate and magnesium ammonium phosphate, but about one-third are pure calcium oxalate.

Stones form more readily infected urine in which bacteria have converted urea into ammonia so making the urine more alkaline.

Vesical Calculus:

Blood stones usually occur either in boys, in young men or in old men (in whom it is generally associ­ated with prostatic obstruction or other cause of urinary stagnation).

Renal Calculus:

Renal colic, the severe pain caused by the passage of stone down the urinary tract. It stops when the stone is passed naturally or removed by a surgeon. Most stones remain in the kidney and they pro­duce no symptoms (silent stones). They may grow there sometimes to a very large size. Infection may lead to pyelonephritis, the commonest cause of chronic renal failure.

Prevention:

(a) Fluid Intake:

A good flow of urine washes out particles of gravel. So water should be drunk before going to bed as urine flow is lowest at night. All patients who have suf­fered from stones should drink sufficient water to produce 2.5 litres of urine daily.

(b) Diet:

The patient should drink only mod­erate amounts of milk and tea and eat only moderate amounts of milk products, meat and fish. Vegetables and fruits may be of benefit by increasing fibre intake.

(c) Drugs:

Bendrofluazide reduces urinary calcium by about 30 per cent. Pyridoxine may be given to patients who form oxalate stones in the hope of diverting glycine metabolism towards serine and away from oxalate. Penicillamine given by mouth is useful in cystinuria, as it combines with cystine which is then excreted in a more soluble form.