MYTHS AND FACTS ABOUT KIDNEY DISEASE

Myth : All kidney diseases are serious and incurable

Fact : Most kidney diseases are treatable. Some are self-limiting and occur only once in a lifetime. Some progress towards renal failure but this progression can be slowed down if the disease is detected early. Even in late cases, treatment may help in reversing or slowing down the loss of kidney function.

Myth : only one kidney is affected by kidney diseases.

Fact : All medical diseases (high BP, diabetes, glomerulonephritis, nephrotic syndrome, poisonings, infections of urinary tract etc) affect both kidneys.

Some structural diseases like tumours, stones, abscesses, renal artery or vein clots, ureteral narrowings, may affect only one kidney.

Myth : I am passing enough urine. Hence my kidneys are not obstructed.

Facts : Most obstructions of the bladder and partial obstructions of the ureter  (stones or accidental ligation during surgery) cause more urine to be formed and passed. Only bilateral total obstruction or obstruction below bladder neck cause reduced urine output.

Myth : I am passing enough urine. Hence my kidneys are healthy and I do not require treatment or dialysis.

Fact : Some kidney disease cause decreased urine output or oliguria (< 400 ml urine/day). Most, however, are nonoliguric or Polyuric (urine output > 3000 ml/day). Even with normal or large urine production, waste material like acids, potassium, urea, creatinine and many more may not be excreted. A person then may require treatment at times dialysis as well.

Myth : Drinking more water will keep my kidneys healthy. This is the treatment for kidney diseases.

Fact : Usual water intake is well managed by thirst in healthy people. Drinking 2-3 litres of fluid may avoid some stone formations and urinary tract infections. Continuing to drink fluids when kidneys are failing or have failed may cause fluid in the lungs (pulmonary edema) or poor control of hypertension. The consequences may be deadly. Follow your doctors’ advice.

Myth : Dialysis once started is required life long.

Fact : In temporary or reversible renal failure, dialysis is required till kidney recovers. In CKD or ESRD with no reversibility, dialysis is required for emergency treatment of high potassium or fluid in the lungs. Maintainance dialysis for uremic symptoms, neuropathy, encephalopathy, pericarditis etc usually means either lifelong dialysis or renal transplant.

Water Balance

Water Balance

Life on earth began in water. Water is the largest molecular constituent of the body. It makes up for about 60% of the total body weight in males and 55% in females.

It provides a medium for metabolic functions in the body. Enzymatic reactions occur in aqueous media. It maintains the form of cells, tissues and organs, helps in digestion, evacuation of body wastes, maintenance of body temperature, lubrication in joints, prevention of infections and many more such functions.

Water Distribution in the body

Of the total body water, 2/3 is in the cells and 1/3 is extracellular. Of the extracellular water, 2/3 is outside the vascular system and 1/3 is in blood.

Regulation of water balance

The osmolality( a measure of solute concentration in water) is held in a very narrow limit in the human body. This typically is 280 to 295 mosm/kg. If the osmolality increases in the body fluids, a hormone called ADH is produced at the base of the brain. This hormone increases thirst and decreases water excretion in the urine thus restoring osmolality.

If excess water is taken, in healthy humans, it is promptly excreted in urine. Even an intake of 8-10 liters in healthy persons may be tolerated.

Water quantities for balance in the body

Body losses of  water

Water is required for cooling down of the body by formation and evaporation of sweat. About 1 ml of sweat is required for losing .58 ml kcal of body heat. Thus about 400-500 ml of water is used in this way depending on environmental temperature, wind velocity, dryness of air etc. 100 -200 ml may be lost in the formation of stools. Small amounts are also lost in vapour form during breathing.

Kidneys excrete about 800 mosm of daily solutes in salt and electrolytes, urea etc. Since maximum urine concentration in healthy adults is about 1200 mosm, 2/3 litre of water is lost in this way daily.

Gains of water from outside

Apart from water ingested directly in fluids and beverages, water is also contained in food. Some fruits may have almost 100% water while most will have 50 to 60% water content. Thus 500 ml to 600 ml of water is ingested in foods. Water in similar quantity is produced by metabolism of proteins and carbohydrates in the body.

Thus to maintain a balance a minimum of about 600-800 ml of water is required to be ingested in the liquid form. An intake of 1.5 to 3 l is sufficient for most cases for healthy living. In old people a litre more water results in better function of the kidney and bladder.

Kidney Biopsy

Kidney Biopsy

Kidney Biopsy is a procedure in which a very tiny piece of the kidney is removed for examination under a microscope for diagnosis of the kidney disease. It may also inform us about prognosis (future course ) of the disease, severity of disease and suggest ways of treatment. The information given below is relevant for cases of native kidney biopsy.

Indications for kidney biopsy:

When urine shows high levels of protein, RBCs or other abnormalities like casts.

Unexplained acute kidney injury

Some cases of chronic kidney disease

renal transplant dysfunction

The procedure of kidney biopsy:

Patients consent is taken.

Blood group is checked.

Tests are done to see that the bleeding and clotting is normal

Ultrasonography to confirm that both kidneys are

present ,

normal or large,

more or less symmetrical,

there is no stone disease, tumour or cyst etc.

The person is made to lie down on his abdomen with the back facing up. After cleaning the area with antiseptics, the site of biopsy is injected with local anesthetic drugs. After a few minutes, a biopsy needle is gradually inserted till it is lying very close to the cortex of the kidney and the site is confirmed by  USG. Then the trigger is pressed. This inserts the needle for a distance of 10-15 mm in the kidney and a piece of tissue (16 to 18 gauge in core diameter ) is trapped in the needle. The needle is then withdrawn and the site dressed in clean sterile gauze. It is pressed for a few minutes with compression of about 1to 2 kgs and patient then turned to lie on his back. His USG is checked for any bleeding after biopsy and shifted to the ward.

He is kept under observation for 24 hrs (sometimes only 6 hrs) for any complications. If none, he or she is discharged and called to attend the hospital with biopsy report.

Processing and transport of biopsy:

The tissue is sent in formalin/ glutaraldehyde or cold saline for different tests. It is usually seen by light microscope and immunofluorescent staining and if available, electron microscopy.

Risks of kidney biopsy:

The common risk is bleeding. It occurs in most cases but usually is insignificant. If a large amount of blood is lost, patient may require blood transfusion and rarely if bleeding is not controlled, the kidney may have to even be removed. Nowadays such occurrences are rare.

The biopsy site or kidney may get infected, lacerated and even deaths after biopsy have been reported. The risk of death is about 1in 1000 to 1 in 10000 at various centers.

Drugs and Kidney

Drugs and Kidney

Medicines are thrown out of the body either by the liver or the kidneys. These medicines may undergo alteration in the body called drug metabolism. The resulting products are drug metabolites. Water soluble drugs or metabolites often get excreted by kidneys.

Mechanism of drug toxicity:

As the concentration in kidneys is high, kidney tissues can be damaged by these drugs. Drugs can be absorbed by kidney cells when these are filtered. If the drug then is neither absorbed back in blood or metabolised by these cells, it can accumulate to toxic levels.

Some drugs can cause an allergy like reaction in the kidneys (antibiotics specially of cephalosporin group) and cause acute kidney injury.

Other drugs eg aminoglycosides, contrast material used in X Ray and CT Studies, anti fungal and anticancer drugs, almost always cause kidney damage if used for long periods or in heavier dosage.

The damage is more severe in already diseased kidneys.

Heavy metals are often used in alternative medical systems. Arsenic, lead, copper, gold and many others can cause various varieties of kidney damage.

This damage caused by drugs may at times be irreversible and lead to CKD requiring life long dialysis or renal transplant.

Prevention :

Drug induced damage can be prevented by avoiding unnecessary drugs, using drugs in correct doses and measuring kidney function regularly to stop the drug if the damage is detected.

For analgesic related kidney injury : See previous posts.

Diet – Kidney Disease

Calories:

A normal person requires 35 kcal/kg body weight /day. If undernourished about 500 more calories and if obese 500 less calories are adjusted from the daily requirement.

Proteins:

Usual adult requirement is 1g/kg /day. In case of chronic kidney disease about .8 gm/kg/day is recommended. Patients on dialysis require about 1.2 to 1.5 g/kg/day.

Proteins from animal sources are absorbed better. However there is uncertainty whether animal proteins i.e. milk, eggs, fish , meat etc are better for preserving the residual renal function in CKD patients.

In nephrotic syndrome the proteins recommended are .8g/kg/day. However daily urine losses in g/day are added to this calculation.

In case proteins are low in the blood, atherosclerosis of arteries is hastened. Cardiovascular and cerebrovascular complications are more common and life expectancy is reduced if S alb is < 3.5gm/dl. Hence if proteins are curtailed, care should be taken that the protein level in blood remains in normal range. Severe protein restriction can also lower body immunity and make a person prone to infections. These are no longer recommended. Fats: These should not form > 40 % of the caloric requirement in the body. Very low intake reduces essential fatty acids and fat soluble vitamins. Each gm of fat provides 9 kcal. Hence in 2000 kcal diet about 60-100 gm of fats /day should not be exceeded. Fats having high levels of polyunsaturated fatty acids are preferred. Sunflolwer and safflower seeds are good sources of PUFA.

Carbohydrates:

Rest of the calories are made of carbohydrates. Complex carbohydrates are better than simple sugars. Simple sugars are avoided in diabetics. These increase triglyceride levels and make a person prone to obesity as well.

Vitamins & Minerals:

Salt restriction is necessary in nearly all hypertensives, patients with edema due to nephrosis , dialysis and fluid overload situations. A watch is kept over salt and water status to prevent both dehydration and  overhydration. In some cases kidneys can lose excessive salt (salt losing states). Your doctor can advise you better in these situations.

In dialysis patients , water soluble vitamins may be lost during dialysis. Supplements of these are then required to replenish body resources.