When your child’s urine looks like cola, it may signal chronic kidney disease

When a child repeatedly passes dark brown or cola-colored urine, there is a condition that should be suspected.

It is IgA nephropathy, a disease where the immune substance IgA accumulates in the glomeruli -- the clusters of capillaries in the kidneys that filter water and waste -- damaging the kidneys. IgA nephropathy can affect anyone, regardless of age or gender.

“When we see pediatric patients with IgA nephropathy, the most common scenario is that they come in within a week of having a cold or experiencing flank pain, and they notice blood in their urine,” said Professor Lee Yeon-hee of the Department of Pediatrics at the Catholic University of Korea Seoul St. Mary's Hospital on the Korean Society of Nephrology's YouTube channel. “Particularly, IgA nephropathy patients often present with urine that is dark brown or cola-colored rather than bright red.”

IgA nephropathy is a disease where long-term treatment and management are crucial, similar to chronic conditions like hypertension or diabetes, rather than infectious diseases such as the common cold.

“When this disease was first recognized, it was thought to have a favorable prognosis. However, with the recent availability of long-term follow-up, it has been reported that a significant number of patients ultimately progress to chronic kidney disease,” Professor Lee explained. “It is a disease where long-term treatment is critical.”

IgA nephropathy is not as common as hypertension or diabetes, but it accounts for a significant proportion of glomerular diseases affecting the kidneys.

“It is quite prevalent, with 20-40 percent of all glomerular disease patients in Korea, both adults and children, diagnosed with IgA nephropathy. It can occur across all age groups, but primarily develops in the teens and twenties.”

The most representative symptom is gross hematuria, appearing as reddish-brown or cola-colored urine. However, it can also manifest as “microscopic hematuria” (visible only through urine tests), proteinuria, nephrotic syndrome, acute nephritis, hypertension, and other diverse symptoms. “The most typical symptom is actually recurrent gross hematuria,” Lee said, stressing that gross hematuria is the overwhelmingly dominant symptom of IgA nephropathy.

Another time to suspect IgA nephropathy in a child is when an abnormality is detected in their school health screening urine test.

“In patients with severe proteinuria detected in school urine tests, renal biopsy results showed that IgA nephropathy was diagnosed in 54 percent of cases. Half of the patients who underwent biopsy due to significant proteinuria had IgA nephropathy,” Lee noted, emphasizing that “school screenings are extremely important.”

When IgA nephropathy is suspected, a kidney ultrasound may be performed in addition to blood and urine tests. The definitive test for confirming IgA nephropathy is a kidney biopsy. “Approximately half of patients are reported to have elevated IgA levels in blood tests. However, the most accurate diagnosis comes from a kidney biopsy,” Lee said, adding, “The diagnosis is made by observing IgA deposits in the kidneys.”

IgA nephropathy is not a curable disease like urinary tract infections or pneumonia. If proteinuria occurs due to this disease, kidney function declines, necessitating consistent treatment.

"To prevent the decline in kidney function, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are primarily used. These are commonly known as antihypertensive drugs, but they are also used to reduce proteinuria in other glomerular diseases," Lee explained.

When proteinuria cannot be suppressed with drugs like ACE inhibitors or ARBs, additional medications are needed. The primary drug is steroids. Professor Lee said, “If proteinuria remains high despite using drugs to reduce it, unfortunately, steroid treatment is necessary. Other secondary drugs, such as different types of immunosuppressants, may also be considered.”

IgA nephropathy can follow various courses, but pediatric patients are known to have a better prognosis compared to adults. “Unlike adults, it is relatively uncommon for pediatric patients to rapidly lose kidney function. Instead, they tend to show a relatively favorable course,” Professor Lee said, adding, “This might be due to earlier diagnosis.”

Typically, the prognosis may be slightly worse if high blood pressure, acute kidney injury, or other complications are present at the time of IgA nephropathy diagnosis. “However, in children, especially with rapid diagnosis and treatment, recovery is often good even in cases with complications. According to reports so far, children progressing to dialysis during childhood or adolescence are extremely rare,” she said.

A truly poor prognosis is characterized by specific findings.

Lee remarked, “Similar to adults, if systolic blood pressure is 140 or higher, or if significant proteinuria persists despite continuous steroid or other medication use, or if kidney function is severely impaired at diagnosis to the point where drug concentration adjustment is necessary, a kidney biopsy often reveals massive IgA deposition in the glomeruli.”

Parents often worry that IgA nephropathy might hinder their child's growth, but the condition itself does not directly cause growth problems. However, if IgA nephropathy worsens, leading to severe proteinuria or progression to chronic kidney disease, it can then impact growth. Long-term steroid use can also threaten height growth, but medical professionals adjust medication regimens considering this risk.

Professor Lee explained, “In most cases where IgA nephropathy is diagnosed during childhood or adolescence, acute progression is rare, so situations causing growth problems are uncommon.” She further stated, “If a child grows more than four centimeters per year before puberty, they are growing within the normal range, so there is no need for excessive worry (when showing this level of height growth).”

The most crucial point in pediatric IgA nephropathy is not to neglect treatment and management simply because the prognosis is not poor. Professor Lee emphasized, "It is reported that among pediatric IgA nephropathy patients diagnosed before age 18, 9.8 percent progress to chronic kidney disease after 10 years, and 24.4 percent after 20 years. To avoid being among those who progress to chronic kidney disease, regular follow-up monitoring is paramount."

Regular follow-up monitoring is crucial in pediatric IgA nephropathy to quickly detect signs of deterioration into chronic kidney disease and to proactively initiate treatment and management.

“It is important to prevent secondary and tertiary kidney damage in advance, adjust medications according to the current condition, and control blood pressure if it becomes elevated,” Professor Lee advised.