expert type icon EXPERT

Guido Filler

Nephrologist (Pediatric)

Dr. Filler is Professor of Paediatrics with cross-appointments to Medicine and Pathology & Laboratory Medicine. He served as Chair of the Department of Paediatrics at Western University and Chief of Paediatrics at the Children's Hospital, London Health Sciences Centre from 2006 to 2016. Born in Germany, Dr. Filler sought international experience early in his life and spent a year in Phoenix, Arizona, where he completed High School. He earned his undergraduate and medical degrees from Hannover Medical School in Germany and completed his specialty training in Paeadiatrics at the same institution. In 1988 he won a prestigious scholarship of the "Deutsche Forschungsgemeinschaft" and spent two years of the subspecialty and research training at the Hospital for Sick Children at Great Ormond Street in London, UK. After his return to Germany in 1990, he became a consult paediatric nephrologist and worked in Hannover and Berlin. He completed a PhD in clinical pharmacology at the Charité Hospital, Humboldt University at Berlin, and promoted to Associate Professor. In 1997, Dr. Filler became acting head of the Division of Paediatric Nephrology at the Charité, where he was able to serve as the principal investigator of the first published randomized controlled clinical trial in paediatric transplantation, comparing Cyclosporine Microemulsion and Tacrolimus. In 1999, Dr. Filler assumed the role as Chief of the Division of Nephrology at the Children's Hospital of Eastern Ontario (CHEO) in Ottawa and was promoted to Professor in 1999. He was also appointed to the Department of Pathology and Laboratory Medicine. Dr. Filler developed the paediatric nephrology unit in Ottawa and established together with Dr. Hutchison, a paediatric continuous renal replacement program at CHEO. He also established a new, superior method for the measurement of renal function in children using a single blood test and the measurement of Cystatin C, a low molecular weight protein. In 2006, he became Chair of the Department of Paediatrics, University of Western Ontario and Paediatrician in Chief. He was renewed for a second term in 2011. Dr. Filler has authored over 300 peer-reviewed publications and is an active participant in a large array of administrative committees within this academic health sciences centre. Apart from his nephrological research (especially cardiorenal syndrome type IV and improving outcomes of children with CKD), he focused on the optimization of paediatric drug dosing by studying parmacokinetic/pharmaco¬dynamic relationships of various drugs in children. Another major field of research is population health and paediatrician workforce based. He is the deputy editor of the journal "Pediatric Transplantation" and he is on the editorial board of paediatric nephrology, transplantation, pharmacology and paediatric journals. He has also been recognized for his postgraduate teaching.
Guido Filler
  • London, Ontario
  • Hannover Medical School
  • Accepting new patients

My daughter is not passing enough urine. Is this an emergency?

Dear Concerned Parent: I understand that you are worried. A decrease in urine output is the most visible sign of acute kidney injury (AKI) in all age groups, particularly younger READ MORE
Dear Concerned Parent:

I understand that you are worried. A decrease in urine output is the most visible sign of acute kidney injury (AKI) in all age groups, particularly younger children. Oliguria occurs when the urine output in an infant is less than 0.5 mL/kg per hour for 24 hours or is less than 500 mL/1.73 m2 per day in older children. Anuria is defined as absence of any urine output.

However, the first thing is to determine whether it is real. Sometimes children hold their urine. It has happened several times that a parent brought the child to the emergency room for decreased urine output, and then the child had a large void while in the emergency room. The most common reason for decreased urine output is dehydration. Dehydration takes place when your body loses more fluid than you drink. The most common cause of water loss from the body is excessive sweating. There are numerous other reasons why you can dehydrated. These include fever (which increases insensible losses), diarrhea, vomiting, a stomach flu, food poisoning, and rarer conditions. There are a number of other conditions that can cause an AKI. These can only be identified with additional tests.

If you are really worried, I would recommend that you consult a physician.

Kind regards,

Guido Filler, MD, PhD, FRCPC

After a kidney transplant, what would my child's life be like?

Dear Concerned Parent, Kidney transplantation is the therapy of choice for end-stage chronic kidney disease (also known as end-stage renal failure). A successful renal transplant READ MORE
Dear Concerned Parent,

Kidney transplantation is the therapy of choice for end-stage chronic kidney disease (also known as end-stage renal failure). A successful renal transplant offers the best metabolic control, the lowest long-term cardiovascular risk, the best longevity, and a better quality of life despite the need for life-long immunosuppression. It is also the cheapest treatment, even though this should not be a factor.
After transplantation, the child will go from the operating room to the paediatric critical care unit for a couple of days. Physicians may push the fluids to maintain high urine output, which improves the monitoring of the kidney function after transplantation. The team will frequently assess the electrolytes and other factors in the blood to make sure that the transplant will work well. You son will have to take antirejection drugs, which may be highly variable from person to person, and may need a lot of adjustments. There will also be repeated imaging of the transplant. Another potential problem is related to viral illnesses that the donor may have had and your son may not yet have acquired, such as cytomegalovirus and the virus that causes mononucleosis (also known as mono). Prophylaxis against pneumocystis pneumonia infection is also needed, possibly life long. It may be necessary to give prophylactic medications. Rarely the transplant may be slow with picking up function, and the patient may have to continue on dialysis for a while.
Once the patient is more stable, he will return to a regular ward and should be discharged soon thereafter. It is not unusual to have high blood pressure after the transplantation. There may be 3 antirejection medications (typically tacrolimus, mycophenolate mofetil and corticosteroids), infection prophylaxis, blood pressure medications and others. It is not uncommon that a magnesium supplement is needed as tacrolimus can induce magnesium wasting. This usually gets better.
After the discharge home, you will have to come to the hospital frequently to check kidney function and medication levels. Due to a lot of drug interactions especially with tacrolimus, this is of high importance. You may be asked to avoid any grapefruit juice. In some cases, there may also be urinary tract infections. All of this is done to prevent acute rejection of the transplant and to minimize infectious complications.
Over time, the frequency of these visits will drop as the issues diminish. In the long run, it may only be necessary to be seen every 3 months. It will be of the highest importance that the antirejection medications are being taken with absolute adherence to the recommendations as rejection of the transplant still remains a major problem. When your son becomes an adolescent, there will be additional challenges with adherence. It may be very wise to educate him about his new condition as much as possible and to develop habits and routines that help to avoid any non-adherence. Non-adherence may lead to donor-specific antibodies and premature graft loss. Your nephrologist may also treat similar issues as with the chronic kidney disease, for instance the blood pressure, or vitamin D therapy, growth hormone therapy if there is insufficient growth despite of good graft function, etc. . These factors are just as important after the transplant as before.
You may notice a big growth spurt in the first year. You may also notice substantial improvements in the school performance, and in the development. Poor kidney function unfortunately affects school performance and cognitive development. It may take a while before some of the toxins of chronic kidney disease are getting out of the body.
Unfortunately, a transplant is not a cure, and there will be underdosing of nephrons which leads to slow deterioration of graft function. If everything goes well, the transplant may work for 15 or 20 years or longer. Ideally, a second transplant is pursued before the patient needs to go back on dialysis. Antirejection medications, especially tacrolimus, may have to be continued even after graft failure to prevent sensitization, which might make retransplantation very difficult. However, with retransplantation, a very respectable life expectancy can be achieved. Most important is the adherence to the antirejection drugs, which have to be finetuned by your nephrologist to avoid too much of too little of it. Therefore, transplantation is a therapy, not a cure. We are fortunate to have this treatment.

My son needs to have a kidney ultrasound. What should we expect?

The most important thing for an ultrasound of the kidneys and the urinary tract is a full bladder. I therefore recommend to drink a lot of water. There is sometimes confusion because READ MORE
The most important thing for an ultrasound of the kidneys and the urinary tract is a full bladder. I therefore recommend to drink a lot of water. There is sometimes confusion because of issues with gas in the bowel and visibility of the kidneys from the side. Indeed, gas reflects the ultrasound waves and makes it more difficult to see especially the lower urinary tract. Sometimes, the radiology centre therefore asks that the patient be fasting, however, this is in contradiction to the need for a full bladder. It is fine to drink water for a kidney ultrasound. I would recommend to avoid foods like beans, lentils, asparagus, broccoli, brussel sprouts, cabbage, and other vegetables as well as foods containing fructose, a natural sugar found in artichokes, onions, pears, wheat, and some soft drinks. Also, avoid lactose, the natural sugar found in milk and milk products. Avoid these foods that make you gassy for the entire day before the scan.
Ultrasound does not hurt. Most kids are quite curious to see into their own belly and do not need anything special. Based on your question, I suspect that your son may have some difficulties or may be anxious. You should explain that some gel needs to be put on his tummy and his back so that there is no air between the ultrasound transducer and the skin. A good radiology centre that does ultrasound in children regularly will have the gel heated so that it does not feel cold. Explain to him that this gel is harmless. Explain that this procedure will not hurt and that he can look inside his tummy. He will likely also have to be prone to see the kidneys from the back. If he does not want to watch his own organs on the screen, you may want to bring a game on a mobile device for distraction. He will have to lie still and cooperate, otherwise it will be very difficult to perform the procedure. Make sure that you bring a bottle of water and let him drink while you are driving to the appointment. Try to avoid that he pees before the appointment. Hope this helps,

Guido Filler, MD, PhD, FRCPC

My daughter's urine output throughout the day is quite low. Could this be caused by a kidney issue?

Dear Concerned Parent: I understand that you are worried. A decrease in urine output is the most visible sign of acute kidney injury (AKI) in all age groups, particularly younger READ MORE
Dear Concerned Parent:

I understand that you are worried. A decrease in urine output is the most visible sign of acute kidney injury (AKI) in all age groups, particularly younger children. Oliguria occurs when the urine output in an infant is less than 0.5 mL/kg per hour for 24 hours or is less than 500 mL/1.73 m2 per day in older children. Anuria is defined as absence of any urine output.

However, the first thing is to determine whether it is real. Sometimes children hold their urine. It has happened several times that a parent brought the child to the emergency room for decreased urine output, and then the child had a large void while in the emergency room. The most common reason for decreased urine output is dehydration. Dehydration takes place when your body loses more fluid than you drink. The most common cause of water loss from the body is excessive sweating. There are numerous other reasons why you can dehydrated. These include fever (which increases insensible losses), diarrhea, vomiting, a stomach flu, food poisoning, and rarer conditions. There are a number of other conditions that can cause an AKI. These can only be identified with additional tests.

If you are really worried, I would recommend that you consult a physician.

Kind regards,

Guido Filler, MD, PhD, FRCPC

Can my son survive on one kidney?

Sorry to hear about your son's chronic kidney disease. Renal transplantation is the therapy of choice for end-stage chronic kidney disease. Pre-emptive transplantation would be READ MORE
Sorry to hear about your son's chronic kidney disease. Renal transplantation is the therapy of choice for end-stage chronic kidney disease. Pre-emptive transplantation would be preferable. If no kidney is available, there is peritoneal dialysis and haemodialysis available for children in most countries. The treatment should be considered a bridging therapy until a transplant becomes available. Peritoneal dialysis may provide more gentle, continuous treatment, but parents have to perform this treatment at home, and there is a risk for infections (peritonitis and exit-site infections). For this, a peritoneal dialysis catheter should be surgically placed into the abdominal cavity, preferably as a swan-neck catheter with two cuffs. For haemodialysis, vascular access is required. Home haemodialysis is not widely available, but provides excellent clearance if done daily, for instance, as slow overnight treatment. In centre haemodialysis is often restricted to thrice weekly and demanding, because all the fluid has to be removed in a short time period. You need to speak with your local paediatric nephrologist to discuss the options. Survival for many years on both dialysis options have been reported in children and adolescents. If no dialysis or transplantation is offered and the chronic kidney disease becomes end-stage, chances for survival are guarded.

My 15 year old son has been diagnosed with kidney stones. How can this be treated?

Your son should be referred to a paediatric urologist for the management of the stones and to a paediatric urologist for the workup for treatable causes. Owing to the poor diet READ MORE
Your son should be referred to a paediatric urologist for the management of the stones and to a paediatric urologist for the workup for treatable causes. Owing to the poor diet and high salt intake, 56% of patients in the paediatric age group now have kidney stones because there is not enough citrate for a given amount of calcium in the urine. The second most common reason is hypercalciuria. Often this is caused by eating too much salt, which leads to calcium wasting. There are rare other causes such as hyperoxaluria and cystinuria or hypomagnesuria that can cause kidney stones and may need very specific treatment. Your paediatric nephrologist can counsel you. For sure, you should start immediately with a high water intake to dilute the urine, and reduce the salt intake to less than 1500 mg per day. This is not easy as 75% or more of the salt in the diet of our children and adolescents comes from processed food. Home cooked meals from scratch are preferable. Read the sodium label. More than 97% of Americans eat more than 1500 mg of salt per day. The salt intake of children and adolescents has increased 10-fold over the past 25 years. There also is insufficient intake of vegetables, which provide the vitally important citrate and potassium. Another source of citrate is lemon juice concentrate. You can encourage the intake of lemon juice, there are even studies with lemonade in the adult literature. Citrate and potassium, apart from high water intake, are the two main minerals that reduce new stone formation. However, while smaller stones may pass, larger stones may require the assistance of paediatric urologists to remove the stone. For sure, pain and blood urine should prompt a visit to the emergency room. Passing stones may be the most painful event known to man. The paediatric urology team has multiple methods to deal with large stones, including lithotrypsy, percutaneous lithotomy, and others. Your paediatric urologist will guide you to the most effective and least traumatic option.

Should I be concerned about kidney conditions in my son?

There are many hereditary kidney conditions that run in families. The most common condition would be autosomal dominant polycystic kidney disease. This is characterized by cyst READ MORE
There are many hereditary kidney conditions that run in families. The most common condition would be autosomal dominant polycystic kidney disease. This is characterized by cyst formation in both kidneys which slowly lead to kidney failure, typically in the 4th to 6th decade of life. This is inherited with a 50% chance from generation to generation and could be diagnosed in your 7-year old son with a kidney ultrasound. It would be helpful to make the diagnosis early because there are now treatments available that may slow progression of chronic kidney disease, including treatment of high blood pressure and tolvaptan. Polycystin I and II gene mutations have been associated with this disorder.
There are other hereditary kidney diseases to consider, for instance, Alport syndrome. This disorder is variable and different genes are implied, which can be tested through a tertiary paediatric nephrology centre. Sometimes patients have hearing loss as well, and occasionally the cornea of the eye may be involved. While there is no specific treatment for this disorder, early treatment may be helpful to slow progression of renal disease.
Certain anomalies of the kidneys and urinary tract may also be hereditary. You will likely have undergone antenatal ultrasounds, and if they were normal, there is probably no concern about this.
There are a number of other conditions that are also genetic, and it would be too long to list them all. Your local paediatric nephrologist can counsel you. Many can be diagnosed early. However, knowledge about the kidney problems in your family will be extremely helpful. By far the most common reason for kidney failure is diabetes mellitus which is poorly controlled. If that is the reason for your family history, and your son does not have diabetes mellitus, then there is nothing to worry about.

My baby is 10 months old and has water retention in her legs. Should we be worried?

Water retention in the legs (or other parts of the body) is called edema. It is not very common. Many conditions are associated with edema, which means that there are many causes, READ MORE
Water retention in the legs (or other parts of the body) is called edema. It is not very common. Many conditions are associated with edema, which means that there are many causes, too. Here are some ways that conditions could cause edema:

Liver disease:

A healthy liver helps to regulate the level of fluid in the body. If the liver is damaged, it may not be able to do this, leading to fluid build-up. Often, this is in the abdomen though, not in the legs. Your pediatrician probably checked the albumin level and liver enzymes. Liver disease in toddlers should be treated by a pediatric gastroenterologist/hepatologist.

Kidney disease:

The kidneys may not be able to eliminate enough fluid from your child’s body. Another possible reason is a low albumin level in the blood because the kidneys are oozing albumin and other plasma proteins. In children of this age, one must test whether there is protein or albumin in the urine and the level of total protein and albumin in the blood. Your child could have nephrotic syndrome. Any kidney disease should be treated by a pediatric nephrologist.

Heart disease:

Edema related to heart disease can be associated with:

* congestive heart failure
* cardiomyopathy
* congenital heart defect

Since your child’s body depends on her heart to pump blood to her organs, poor cardiac function can cause edema in several ways:

* If your child’s heart, for whatever reason, isn’t pumping blood efficiently, blood can build up in the parts of her body furthest from the heart, such as the legs, ankles, and feet.
* This puts increased pressure on the tiny blood vessels called capillaries, which may begin to leak blood into the surrounding tissues, causing swelling.
* Because of the poor heart function, the kidneys sense less blood fluid available and begin to conserve water and sodium.
* Also, without sufficient blood supply, the kidneys have a harder time doing their job of ridding the body of excess fluid.
* Eventually, this excess fluid builds up in the lungs.

What are the other symptoms of edema?

Aside from the actual swelling, you or your child may notice your child:

* feeling tired after minimal physical exertion, like climbing stairs
* gaining weight
* having trouble breathing
* with a cough that gets worse at night or when she is lying down. This may be a sign of acute pulmonary edema, or excessive fluid in the lungs, which requires emergency treatment.

There are also some other reasons which are very rare. Your pediatrician will screen for liver, kidney, and heart disease and make appropriate referrals to subspecialists. The cause of the edema must be identified and treated.

Kind regards,

Guido Filler, MD, PhD, FRCPC

My child has frequent UTIs -- What's wrong?

Dear troubled mother: There is something about a 7-year old girl having frequent urinary tract infections. Whereas we see more boys in almost all age groups, girls in that age READ MORE
Dear troubled mother:

There is something about a 7-year old girl having frequent urinary tract infections. Whereas we see more boys in almost all age groups, girls in that age frequently present with recurrent bladder infections. There are multiple reasons. However, this is the first thing to answer:

1. Were these really urinary tract infections (UTIs). What were the symptoms? Sometimes crystals in the urine can give you the exact same symptoms such as frequency, urgency, accidents, painful urination. Unfortunately, the average child consumes a high salt, high protein and no vegetable diet. This leads to many problems, including calcium wasting due to a high sodium load in the distal tubule, low urine pH because of the acid load from animal protein and sugary food, and a loss of urinary citrate as well as a low potassium intake for which vegetables are the most important source. Also, the children don't drink enough. As a result, you get a concentrated, acidic urine with a high calcium and sodium content and a low urinary citrate: The perfect storm for crystals in the urine or even stones in the urinary tract.
Every 5-10 years, we see a doubling of the incidence of kidney stones in children. The biggest factor is the salt, and it is not from what you add when cooking. Prepared food are full of sodium. The average 7-year old consumes 2,944 mg of sodium per day (National Health and Nutrition Examination Survey, United States, 2007-2008), whereas an adult should take in less than 2,300 mg/day and you have to scale this down to maybe half for a 7-year old. If that is the problem, avoid all processed food, cook yourself from scratch, and add a lot more vegetables to the diet. A simple test checking for urinary sodium, potassium, calcium and creatinine may be very telling.

2. Assuming there were bacteria. The definition of a UTI is not bacteria in the urinary tract, but rather inflammation BECAUSE of bacteria tract. You want to see a significant colony count on the culture together with either white blood cells and/or nitrates on a urinary dipstick. Blood may have different reasons. A vulvitis (Inflammation of the external genital organs of the female (the vulva) can lead to abnormal urine findings. Is she sometimes red in her privates? Then treat that rather than UTIs. Little girls are more prone to external infections in their privates than adults. In an adult woman, the pH in the privates is low, whereas a little girl has the same mild pH barrier in her groin as on her skin: pH 5.85. Bubble bath and alkali can destroy the pH barrier and cause a vulvitis. You may have to switch to showers, unscented pH-balanced body wash agents, and blow dry the inflamed area after a shower with cold air to get rid of the problem. The symptoms can be very similar to a urinary tract infection. Sometimes, there are yeast infections and the antibiotics commonly prescribed for UTIs may make it worse.

3. Let us say, it was a UTI. There were nitrates and leukocytes on dipstick and a significant colony count in the urine culture. There can be two reasons: high pressure or backwash (reflux) from the bladder into the ureters, the tubes that connect the kidneys with the bladder.
Let us start with high pressure. The most common reason is constipation. Owing to low vegetable (and thus soluble fibre) intake, many children are constipated. Sometimes, it may be so bad that you get fecal impaction. A fecal impaction is a solid, immobile bulk of human feces that can develop in the rectum as a result of chronic constipation. A related term is fecal loading which refers to a large volume of stool in the rectum of any consistency. There can even be fecal incontinence and paradoxical or overflow diarrhea (encopresis) as liquid stool passes around the obstruction (blockage). The distal colon is supposed to be a narrow tube and the bowel movement should be once a day and look like thin snakes (see Bristol Stool chart type IV). Typically a 7-year old passes stool after supper. Think of a large freight train. You push one car in, and then the last car needs to be pushed out. It is supposed to work the same. You have two valves, the inner (I gotta go) valve and the outer (not now) valve. When a child is chronically constipated, the bowel is wide and the inner valve is always open and the normal reflex with a bowel movement 20 minutes after supper does not work. To fix this, you need to give PEG3350 (Restorelax), and enough of it to prevent the stool from being hard, and long enough to make the bowel shrink again. This may take 3 months, and even thereafter you should wean the PEG3350 slowly to get rid of the problem once and for all. Sometimes it is easy to diagnose constipation using the Bristol stool chart. Occasionally, you may need an X-ray to see a large stool mass.

4. It should be noted that holding the pee also can lead to high pressure. Is your daughter a busy bee that is too busy to go to the washroom? She is so involved in playing or whatever she is doing that she is holding her pee? In that case, remind her to go during every recess and every 2 hours at home. She also should be reminded to take her time with peeing, perhaps even count to 20 when she thinks she is done and then pee again to make sure that the bladder is always empty. Sometimes the bladder gets so distended with holding the urine that it is impossible to empty it completely, hence the recommendation to "double void".

The steps to double voiding are as follows:

* sitting comfortably on the toilet and leaning slightly forward
* resting the hands on the knees or thighs, which optimizes the position of the bladder for voiding
* urinating as normal, focusing on emptying the bladder as much as possible
* remaining on the toilet, waiting anywhere from 20 to 30 seconds
* leaning slightly further forward and urinating again

5. Let us say there is no constipation and it were true UTIs. Were they with fever? If they were with fever, you have to assume that the kidneys were involved. We call this a pyelonephritis. This should be worked up and an ultrasound of the kidneys and possibly a test for backwash (reflux) from the bladder (VCUG) into the ureters should be considered. The ultrasound is harmless, and it will be very reassuring if it is normal. The VCUG should be considered if the ultrasound is not normal. It is not the nicest test because it requires a bladder catheter to put the dye into the bladder. Careful, playful explanation is important to reduce the trauma of this test. However, it will be very helpful to assess for reflux and any bladder abnormality. In that case, you may want to ask your doctor for a referral to a specialist (paediatric nephrologists and paediatric urologists). There are not many of them and they are typically only in the large children's hospitals or the university hospitals. If the UTIs were without fever, a little girl is allowed to have three before more tests should be considered.

Hope this is helpful and you can resolve the issue.


Kind regards,
Guido Filler, MD, PhD, FRCPC