Understanding the Causes of Glomerulonephritis in Children
What Is Glomerulonephritis in Kids?
Glomerulonephritis refers to a group of kidney disorders that involve inflammation of the glomeruli—the tiny filtering units in the kidneys responsible for removing waste and excess fluids from the blood. When these structures become damaged, it can lead to problems like proteinuria (protein in urine), hematuria (blood in urine), swelling, high blood pressure, and even impaired kidney function. In children, this condition can develop suddenly or progress slowly over time, depending on the underlying cause.
Types of Pediatric Glomerulonephritis
Glomerulonephritis in children is generally categorized based on the duration and progression of symptoms: acute, persistent (or prolonged), and chronic forms. Acute glomerulonephritis often appears after an infection and may resolve within weeks to months. Persistent cases last longer than six months but don't meet full criteria for chronic disease, while chronic glomerulonephritis involves long-term kidney damage that may eventually lead to renal failure if untreated.
Post-Infectious Glomerulonephritis: A Common Trigger
The most frequent cause of acute glomerulonephritis in children is a post-infectious immune response, particularly following a streptococcal infection such as strep throat or impetigo. This specific type is known as post-streptococcal glomerulonephritis (PSGN). Although the initial infection may have cleared, the body's immune system mistakenly attacks the kidney filters, causing inflammation. Other pathogens—including certain viruses, Mycoplasma pneumoniae, and less commonly, bacterial endocarditis—can also trigger similar immune-mediated kidney injury in pediatric patients.
Primary vs. Secondary Glomerular Diseases
Beyond infections, childhood glomerulonephritis falls into two broad categories: primary and secondary. Primary glomerulonephritis occurs when no clear systemic illness is identified. Instead, it's believed to result from a combination of genetic predisposition, immune dysregulation, and environmental triggers. Conditions like minimal change disease, focal segmental glomerulosclerosis (FSGS), and IgA nephropathy are common examples seen in this category.
Systemic Illnesses Leading to Secondary Glomerulonephritis
Secondary glomerulonephritis arises due to well-known systemic diseases affecting multiple organs, including the kidneys. Among the most prevalent types in children are:
- Henoch-Schönlein purpura (HSP) nephritis – an autoimmune condition triggered by abnormal immune complex deposition, often following a viral illness, leading to skin rash, joint pain, abdominal symptoms, and kidney involvement.
- Lupus nephritis – a complication of systemic lupus erythematosus (SLE), where the immune system attacks various tissues, including the kidneys. While more common in older children and adolescents, especially girls, early diagnosis is critical to prevent irreversible damage.
- Hepatitis B-associated glomerulonephritis – particularly observed in endemic regions, this form results from immune complexes formed by hepatitis B virus antigens depositing in the glomeruli, mainly affecting younger boys.
Genetic and Hereditary Kidney Disorders
A smaller yet significant number of pediatric glomerulonephritis cases stem from inherited genetic mutations. These conditions often run in families and may present with isolated microscopic hematuria or progressive protein loss in urine. Examples include Alport syndrome, congenital nephrotic syndrome, and thin basement membrane disease. In such cases, abnormal genes affect the structure and function of the glomerular basement membrane, compromising the kidney's filtration ability from birth or early childhood.
Recognizing Risk Factors and Family History
Children with a family history of kidney disease, unexplained hematuria, or early-onset proteinuria should be closely monitored. Genetic testing and counseling may be recommended when hereditary causes are suspected. Early detection allows for timely interventions that can slow disease progression and preserve kidney health.
Conclusion: Importance of Early Diagnosis and Management
While the origins of glomerulonephritis in children vary widely—from infections and immune disorders to genetic factors—early recognition of symptoms like foamy urine, facial swelling, or reduced urine output is crucial. With proper medical evaluation, including urinalysis, blood tests, imaging, and sometimes kidney biopsy, many forms of pediatric glomerulonephritis can be effectively managed. Parents and caregivers play a key role in observing changes and seeking prompt care, helping ensure the best possible outcomes for affected children.