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


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.


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.


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.

Our Kidneys

Our Kidneys

Common Questions

  • Are both my kidneys affected?

Ans. Most diseases involve both kidney diseases simultaneously. Exceptions are obstructions in one kidney or ureter, the tumor of one kidney, injury to one kidney or ureter, infections confined to one kidney etc.

However, some people may be born with only one kidney!

  • Have both my kidneys failed?

Ans. If the urea and creatinine are high, it means both kidneys are functioning less. If one kidney function is normal, urea and creatinine are usually not elevated.

  • Will the kidney function recover with dialysis?

Ans:     Dialysis does not improve kidney function. It is a substitute for some of the kidney functions. In acute kidney injuries, dialysis may buy time and allow the kidneys to start functioning again. In Chronic kidney disease, unless there are some reversible elements, the kidney function will not only not recover but the residual function will also decrease with time.

  • Do kidney donors lead a normal life? Can they do heavy work?

Ans:     After the nephrectomy operation, recovery takes about 2 to 3 months. Once the muscle scars have healed well, the donors can lead a normal life.

Stone Disease of the Kidneys

Stone Disease of the Kidneys.

Stone formation in the kidneys is a common disease. About 1in 8 men and 1 in 20 women suffer from the symptomatic stone disease. Stone formation without symptoms is even more common.

About ¾ of the stones contain calcium and 10% have uric acid. Rest are due to combinations and rare diseases.

Calcium Stones

These contain calcium oxalate or calcium phosphate. Former is more common.

The risk factors for stone formation are

In Urine 

Low volume , High calcium in urine, high acid concentration and low citrate levels.

In Diet

Water and fluid intake is low, fruits are seldom eaten, food has high oxalate level or if calcium content of the diet is on the lower side.

Other diseases with high risk for stone formation are overweight, gout, diabetes, recurrent urinary tract infection etc. Bariatric surgery is a very significant risk factor.

If kidneys have certain diseases like the inability to excrete acid, a stone formation may occur.

Symptoms: Stones if they are in the urinary path (ureters or urethra) pain colicky in nature often radiating from back to lower abdomen or upto urine passage opening (urethra) may occur. This pain is at times very severe necessitating urgent consultation.

Urine may be passed in drops and is often red in colour due to blood.

If the passage of urine is blocked due to stone at any site, high pressure develops upstream of the blockage. If not treated early this may permanently damage the kidney.

In India, an untreated stone disease is a common cause of permanent renal failure.

Stone analysis, various urine tests aid in finding the underlying cause of stone formation. A cause is found in about ½ of the cases.


Stone disease can usually be prevented by adequate water intake, fruits or fruit product ingestion, enough calcium and lower salt in the diet and early complete treatment of urinary tract infection.

Eating lower oxalates in the diet is of questionable value.

Small stones pass spontaneously with more fluid ingestion and alpha blockers. Large stones need to be removed by surgery.

Prevent Swine Flu

How to prevent Swine flu:

Take vaccines. These vaccines keep undergoing changes depending on the current viruses. Since it takes 6 months to produce a vaccine, the vaccine available now is based on the likely viral types as seems most likely from last influenza season.

Children > 6 months of age, older adults >65 yrs, pregnant woman, asthmatics, Chronic liver, heart and kidney disease patients, those suffering from neurological illnesses should certainly take vaccines.

Treatment with antiviral drugs are recommended in all these cases as they suffer more complications.

Health care workers are more likely to come in contact with flu patients and should be vaccinated.

Personal protective measures:

Stay away from people suffering from infectious respiratory illness.

Wash hands often with soap and water or if not available alcohol based solutions.

Do not touch eyes, mouth or nose often.

Use a handkerchief or tissue during sneezing or coughing. Disposable tissues are better.

After an episode of fever do not go to school or work place till the temperature is normal for > 1 day without antipyretics.