Most kidney problems in children show up through changes you can spot at home: unusual urine color, unexplained swelling, fatigue, or shifts in how often your child uses the bathroom. Some signs are subtle, like slow growth or new bedwetting in a child who was previously dry at night. Others are hard to miss, like puffy eyes first thing in the morning or urine that looks pink or foamy. Knowing what to watch for can help you catch a problem early, when treatment works best.
Changes in Urine
Your child’s urine is one of the most reliable early indicators of kidney trouble. Healthy urine ranges from pale yellow to slightly darker yellow depending on hydration. When the kidneys aren’t filtering properly, you may notice several distinct changes.
Pink or cola-colored urine signals blood in the urine, a condition called hematuria. It doesn’t always mean something serious, but it always warrants a call to your pediatrician. Foamy urine, the kind that looks like it could sit in the toilet bowl for a while without dissolving, suggests excess protein leaking through the kidneys. This happens when the kidney’s filtering units are damaged and can’t hold protein back the way they should.
Pay attention to how often your child goes to the bathroom, too. Children typically urinate four to seven times a day. Urinating eight or more times a day, or going only two to three times, falls outside the normal range. A child who suddenly starts wetting the bed again after being dry at night (most kids are reliably dry by age five or six) may be producing more urine than usual because the kidneys aren’t concentrating it properly.
For babies and toddlers who can’t tell you how they feel, wet diapers are your main clue. No wet diaper for three hours or longer, combined with crankiness or low energy, can point to a kidney or dehydration issue that needs attention.
Swelling, Especially Around the Eyes
Swelling that doesn’t go away is one of the hallmark signs of kidney dysfunction in children. When the kidneys leak too much protein into the urine, protein levels in the blood drop. Since blood proteins help keep fluid inside blood vessels, low levels let fluid seep into surrounding tissue and collect there.
In children, this swelling (called edema) shows up in characteristic places. Puffiness around the eyes, particularly in the morning, is the most common early sign of nephrotic syndrome, one of the more frequent kidney conditions in kids. Swelling can also appear in the lower legs, feet, hands, abdomen, and face. Some parents initially mistake this for allergies or a rough night of sleep, but kidney-related puffiness tends to persist day after day rather than coming and going.
Slow Growth or Falling Off the Growth Chart
Chronic kidney problems can quietly interfere with a child’s growth long before other symptoms become obvious. When the kidneys don’t filter waste effectively, those waste products build up in the blood and block the body’s ability to use growth hormone normally. The hormone is still being produced, but the body can’t respond to it the way it should.
Pediatricians track growth on percentile charts at well-child visits. If your child’s height or weight starts dropping to a lower percentile over time, or if they seem noticeably shorter than peers of the same age and sex, it’s worth asking whether kidney function should be checked. Growth failure doesn’t always mean kidney disease (many things affect growth), but it is one of the recognized consequences of chronic kidney dysfunction in children.
Fatigue and Low Energy
Children with kidney problems often seem unusually tired. Part of this comes from the kidneys’ role in producing a hormone that tells the body to make red blood cells. When kidney function declines, fewer red blood cells get made, leading to anemia. With fewer red blood cells carrying oxygen around the body, your child may seem pale, sluggish, or uninterested in activities they normally enjoy. They may have trouble concentrating at school or seem irritable without a clear reason.
This kind of fatigue is different from the tiredness you see after a busy day or a growth spurt. It tends to be persistent, showing up day after day regardless of how much sleep your child gets.
High Blood Pressure
Most people don’t associate high blood pressure with children, but it’s one of the more common findings in pediatric kidney disease. The kidneys play a central role in regulating blood pressure, so when they’re not working properly, blood pressure can creep up. In children, high blood pressure is defined as readings at or above the 95th percentile for their age, sex, and height on three or more separate occasions.
The tricky part is that high blood pressure in children rarely causes symptoms you can see. Unlike in adults, kids don’t typically complain of headaches or dizziness until the numbers are very high. Research has found that children with elevated blood pressure also tend to score lower on cognitive tests compared to children with normal readings, so subtle changes in school performance could be a clue. Your child’s blood pressure is checked at routine well visits, which is one reason those appointments matter even when your child seems perfectly healthy.
Loss of Appetite and Nausea
As kidney function declines, waste products that should be filtered out of the blood start to accumulate. This buildup can make a child feel nauseated, reduce their appetite, or cause vomiting. Young children may simply refuse food or eat much less than usual without being able to explain why. In older kids, you might hear complaints about feeling sick to their stomach, especially in the morning.
Who’s at Higher Risk
Some children are more likely to develop kidney problems because of how their kidneys or urinary tract formed before birth. Congenital anomalies of the kidney and urinary tract account for 20 to 50 percent of all birth defects, with a collective prevalence of 4 to 60 per 10,000 live births. The most common upper urinary tract conditions include multicystic dysplastic kidneys (occurring in roughly 1 in 2,200 to 4,300 births), kidneys that didn’t fully develop, or a missing kidney on one side (about 1 in 1,000 to 2,000 births).
Many of these conditions are picked up on prenatal ultrasounds, but not all. Children with a family history of kidney disease, those who had frequent urinary tract infections as infants, or those born prematurely may also carry higher risk. If any of these apply to your child, mention it to your pediatrician so they can keep a closer eye on kidney function over time.
What Testing Looks Like
If your pediatrician suspects a kidney problem, the first steps are straightforward and not painful. A simple urine test can detect protein or blood that shouldn’t be there. A blood test measures how well the kidneys are filtering waste by estimating something called the glomerular filtration rate, or GFR. Normal GFR values are lower in babies and toddlers than in older children. In infants under about five weeks old, the average is around 52, rising gradually to about 104 in children older than two. Because of these age-related differences, the same number can be normal for a baby but concerning for a school-age child.
An ultrasound of the kidneys and urinary tract gives the doctor a picture of the kidney’s size, shape, and structure without any radiation. Depending on results, further testing might include more specialized imaging or, in some cases, a small tissue sample from the kidney to look at under a microscope.
Signs That Need Prompt Attention
Some combinations of symptoms deserve a same-day call to your pediatrician or a trip to urgent care: sudden, significant swelling in the face or legs along with dark or foamy urine; visible blood in the urine that doesn’t resolve after one bathroom trip; a sharp drop in urine output over 24 hours; or persistent vomiting with fatigue and swelling. None of these necessarily mean something catastrophic, but they all require evaluation sooner rather than later.
Trust what you observe. Parents are often the first to notice that something is off, whether it’s a change in energy, a new pattern at the toilet, or puffiness that wasn’t there last week. Kidney problems in children are highly treatable when caught early, and most initial testing is quick and noninvasive.