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Acute Kidney Injury

Acute kidney injury (AKI) is a condition where our kidneys suddenly lose their function. Various causes like severe infections, dehydration, renal toxic drugs/envenomation (snake bite, wasp sting), blood clots in renal artery and autoimmune diseases can cause AKI

What are the symptoms of kidney disease?How can we find out this problem?Is it safe to undergo renal biopsy in children?Can we cure the disease?Can the children also have high blood pressure?How do you measure the kidney function? Do you have any grading?Do they need any diet restriction?How do you treat?Can you explain about various RRT measures?Is it possible to do kidney transplant in children?

What are the symptoms of kidney disease?

Poor appetite, nausea, vomiting, breathlessness, body swelling, headache, seizures, reduced urine output will be the presenting manifestations at the end stage of renal failure as well as in acute kidney injury. Apart from these symptoms children with CKD can present with increased water intake secondary to thirst, poor growth, bony abnormalities (wrist widening, bowing of knees).

How can we find out this problem?

With the above said problems your doctor will decide about few essential blood/ urine tests and also imaging like ultrasound depending upon the suspicion.

Urine examination may show protein/ red blood cells in the urine.
Blood tests may show increased levels of toxic products like urea, creatinine. In renal diseases we can also find electrolyte abnormalities, anemia, high/low blood levels of calcium, high phosphorous and parathyroid hormone levels, low vitamin D levels.
Ultrasound may give us a clue about kidney sizes, structural malformations and renal stones.
In case of suspected glomerular disease renal biopsy will be very helpful to know the underlying pathology and chronicity of the disease.

Is it safe to undergo renal biopsy in children?

To know the cause of renal failure we do renal biopsy. Before the biopsy your doctor will do some blood tests to look for the normal blood clotting mechanisms of the child. It is mandatory to keep the child nil per oral for 6 hours before the biopsy. Child is asked to lie in prone position so that the doctor will be facing the back. Procedure will be done under ultra sound guidance. Child will not feel the pain as we use intravenous and local anaesthesia. Two tiny pieces of renal tissues will be taken from the left kidney by using the renal biopsy gun and the same will be sent to studies like light microscopy, immune fluorescent and electron microscopy studies. The wound site will be closed with a gauze and band aid. The pediatric nephrologist will do the procedure. After the biopsy child is advised to take strict bed rest for 24 hours. Following the biopsy, child may pass blood stained urine which is usually benign and settle with subsequent urination. The child can take food/drink after 4 hours of the procedure.

Can we cure the disease?

Acute kidney injury is curable if the cause is reversible like infection or a drug causing AKI. Consult the doctor early and start the treatment. Obstruction like PUV, pelviureteric junction obstruction can be corrected surgically. Any AKI can progress to CKD. So it is advisable to be under regular follow up with a pediatric nephrologist/urologist. We cannot cure chronic kidney diseases. We can keep the disease under control with supportive treatment. But once a critical fraction of function has been lost, renal function progressively worsens independent of the underlying disorder. Childhood nephrotic syndrome is treated with steroids. In case of recurrent relapses, alternative drugs will be tried with serial monitoring for drug adverse reactions. Immuno suppressive therapy may be needed for some glomerular diseases like SLE, vasculitis. Control of proteinuria and hypertension plays a major role in controlling the CKD progression. Some children will have loss of some acids, potassium, chloride in the urine which are essential for the growth of the child. Hence the doctor will give medicines for the same depending upon the underlying disease. Even after surgical intervention for PUV, PUJ problems, children should be under follow up to look for growth, BP and renal functions monitoring. Whenever they get stressed like any infection/ during the growth spurt of adolescence where muscle mass increases, the work load to the kidney also may increase. So it is advisable to be under regular follow up.

Can the children also have high blood pressure?

Yes. Renal problems are the most common cause of hypertension in children. Optimized BP control has a protective effect on the kidneys.

How do you measure the kidney function? Do you have any grading?

We calculate the estimated GFR(eGFR) by using serum creatinine levels. We also do 24 hours urine creatinine clearance in older children. With the either one of the formula CKD is graded as stage 1 to 5. AKI also has grading like risk, injury, failure, loss and end stage renal failure depending on the level of creatinine and urine output.

Do they need any diet restriction?

Your doctor will give careful dietary advice as the children should not be compromised on their growth but at the same time symptoms due to accumulation of waste products also have to be minimized. Nutrtion is important in various phases of growth in children especially during infancy, early childhood as the growth velocity is very high at this age. Depending upon the disease stage and associated blood chemistry alteration they may need restriction. Balanced diet in the form of food containing carbohydrate 60%, fat 30% and 10% protein is advisable. In childhood nephrotic syndrome, it is advised to avoid extra salts like pappad, chips and pickles. Salt restriction is needed in children with hypertension. Food with high biological value protein like egg and milk can be given. In CKD stage 3, 4 & 5, risk of getting the elevated potassium is high. Hence it is advisable to restrict fruit juices, high potassium containing foods. In case of swelling and increase in intra dialytic weight, they may need fluid restriction. Children on RRT may need vitamin supplement to compensate for dialysate loss.

How do you treat?

AKI not responding to conservative measures may need renal replacement therapy(RRT) in the form of peritoneal dialysis(PD), hemodialysis(HD) or continuous renal replacement therapy(CRRT). In HUS, therapeutic plasma exchange is done. CKD children may need RRT usually at stage 4/ 5 and earlier in case of growth retardation, electrolyte imbalance. All the RRT measures are the bridge between the disease stage and kidney transplantation which is the final treatment for any form of CKD ESRD.

Can you explain about various RRT measures?

Peritoneal dialysis During the acute illness it can be done. By using a PD catheter, fluid will be sent inside the abdominal cavity. The peritoneal membrane will act as a kidney and toxins will be replaced with good fluid. All the excessive salt will be drained out. It will go throughout day and night. In children with CKD, the same will be done by continous ambulatory peritoneal dialysis(CAPD). The catheter will be placed surgically inside the abdomen by the pediatric urologist. After a week of procedure, dialysis can be started. Parents/care taker will be taught about the technique of doing CAPD at home by a trained CAPD staff. Hemodialysis During the acute illness, your doctor will secure the central venous line with the catheter on the side of the neck/ thigh region. The blood will be pumped out from the body through the tubing which is already connected to the HD machine. The artificial kidney in the machine will purify the blood and will be sent back to the patient. Usually the duration will be 4 hours. In case of CKD, fistula will be created by connecting the vein and artery in one of the hands. It will take 4 to 6 weeks to mature. Then the fistula site will be pierced by the needle, blood will be pumped out and HD is done. Usually 3 sessions of HD in a week will be enough to remove the waste products. The fistula is usually created in the non dominant hand. That hand should not be used for taking blood samples/ BP checking. CRRT It is done in AKI only, will be done over 24 hours with the CRRT machine. In children with heart compromise and AKI this will be very useful.

Is it possible to do kidney transplant in children?

Yes. Same like adults children also can undergo transplantation. Few criteria are there to select the donor. The work up will be done by the pediatric nephrologist. If everything matches, they will proceed with transplant. However even after transplant child should be on immunosuppressive therapy for long period to prevent rejection.