RENAL FAILURE - ACUTE AND CHRONIC
Causes, symptoms and dietary management
Acute renal failure
There is
sudden shutdown of renal function following injury to the normal kidney. This
is a condition in which the kidneys are no longer able to maintain the normal
composition of the blood.
Causes
1.
Loss of blood due to accidents and internal
hemorrhage. Ulcers can cause acute renal failure as the blood flow to the
kidneys decreases.
2.
Loss of plasma as in burns.
3.
Inhalation or ingestion of poisons such as
carbon tetrachloride or mercury
4.
Shock from surgery
5.
Nephritis and Nephrosis can result in acute
renal failure.
a.
Symptoms
6.
Uremia - There is retention of urea and others
urinary constituents in the kidney.
7.
Azotemia - accumulation of nitrogenous
constituents in the blood.
8.
Oliguria - a scanty output of urine (less than
500 ml)
9.
Anuria - minimal production or absence of urine
(less than 100 ml per day).
10.
Serum potassium levels are high when tissue
proteins are broken down to provide calories.
11.
There is increased phosphate and sulphate with
decreased sodium, calcium and base bicarbonate.
12.
Patients are lethargic, anorexic, have nausea
and vomiting.
Dietary Management
Energy
A minimum
of 600-1000 kcal is necessary. In the initial period when oral intake is less
due to vomiting and diarrhoea, 100 g per 24 hours intravenous glucose is given
to reduce protein catabolism.
Proteins
Initially a protein free diet is used in the non-dialysed patients. In
the diuretic phase 20-40 g protein is given. The protein content of the diet
varies depending on the urea content of the blood.
Carbohydrates
A minimum of 100g per day is essential to minimize tissue protein
breakdown.
Fluid
Fluid allowance is regulated in accordance with
urinary output. The total fluid permitted is 500 ml + losses through urine and
gastro intestinal tract. With visible perspiration an additional 500 ml may be
given.
Sodium
Sodium restriction is judged based on the sodium loss in the urine. For
the non-dialysed patient 500 to 1000 mg per day is given. Patients on dialysis
are permitted 1500 to 2000 mg per day.
Potassium
Potassium allowance is based on serum levels.
Hyperkalemia (potassium intoxication) has deleterious effects on the heart.
Potassium sources like tomato juice, coffee, tea, cocoa are avoided.
Chronic Renal failure
It is also known as uraemia as the level of urea in blood is very high.
This occurs when 90 per cent of the functioning renal tissue is destroyed. It
may be the end result of acute glomerulonephritis and nephrotic syndrome.
Causes
1.
Progression of acute nephritis or nephrosis
2.
Chronic infection of the urinary tract.
3.
Kidney stones
4.
High blood pressure
5.
Exposure to toxic substances.
Once chronic renal failure occurs, the normal functions of the kidneys
like regulation of body fluids, electrolytes, pH and excretion of
metabolites are disrupted.
Symptoms
In chronic renal failure symptoms appear when the glomerular filtration
rate (GFR) is inadequate to excrete nitrogenous wastes. When the GFR is less
than 10 ml per minute (normal 120 ml per minute) and the serum urea nitrogen
(SUN) is more than 90 mg per day (normal 8 to 18 mg per day) dietary
modification brings about improvement. As GFR falls, daily protein intake is
restricted.
1.
The symptoms of the gastrointestinal tract are
nausea or vomiting. The breath has an ammoniacal odour. Ulcerations of the
mouth and hiccups interfere with food intake.
2.
The nervous system - Patients are drowsy,
irritable and sink to coma.
3.
If there is hypertension, headache, dizziness,
muscular twitchings and failing vision occur.
4.
The functioning of the heart is seriously
disturbed
5.
Death results when hyperkalemia (elevated serum
potassium) block the contraction of the heart.
Dehydration,
sodium depletion, high serum potassium, acidosis, increased susceptibility to
infection are the most general manifestations.
Dietary Management
The objectives of treatment are
1.
To maintain optimal nutritional status
2.
To minimize uremic toxicity
3.
To prevent protein catabolism
4.
To improve the patients well-being
5.
To delay the progression of renal failure
6.
To delay the need for dialysis
Energy
Adequate kilocalories are essential to spare
protein for tissue protein synthesis. Without adequate calorie intake body
tissues will be rapidly catabolized thus increasing the blood urea and
potassium levels. For adults calorie needs range from 35 - 45 kcal per kg of
ideal body weight or 2000 to 3000 kcal per day.
Protein
Failing kidneys need to be given rest. Protein intake can be reduced to
0.5 g/kg body weight per day. Haemodialysis patients need 1.0g protein per kg
body weight daily to compensate for losses of amino acids in the dialysate. The
aim is to provide half of the protein allowance as high biological value
protein.
Carbohydrate and Fat
Elevated serum triglycerides common in chronic renal disease can be
lowered by controlling carbohydrate intake, dietary cholesterol and
polyunsaturated fat.
Potassium
This is
restricted to 1m mol / kg body weight. Potassium allowance is in accordance
with the patients blood levels, urinary output and amount of potassium in the
dialysate.
Sodium
Dietary sodium intake depends on the amount of sodium in serum and
urine. Restriction is necessary if edema, hypertension and threat of congestive
heart failure is present.
Vitamins
Losses of ascorbic acid and many B vitamins occur during dialysis.
Intake is likely to be low as raw fruits and vegetables are restricted. Folic
acid and pyridoxine requirements are increased. Due to impaired vitamin D
metabolism supplements are needed.
Fluids
Intake of fluids needs to be monitored. 500 ml over the normal urinary
output is allowed if there is no oedema and hypertension.
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