Causes of Nephrotic Syndrome in Children: Understanding the Underlying Factors
Nephrotic syndrome in children is a complex medical condition characterized by excessive protein in the urine, low levels of protein in the blood, high cholesterol, and swelling (edema), especially around the eyes, feet, and abdomen. While it may appear suddenly, the underlying causes are often multifaceted. Understanding these root factors can help parents, caregivers, and healthcare providers manage and treat the condition more effectively.
Primary Nephrotic Syndrome: Immune System Triggers
The most common form of nephrotic syndrome in children is known as primary nephrotic syndrome. Although the exact cause remains unclear, medical experts believe it is closely linked to abnormalities in the body's immune system. In this type, the immune system mistakenly attacks the kidneys' filtering units—called glomeruli—leading to increased permeability and protein leakage into the urine.
Role of Infections as Precipitating Factors
In many cases, an infection acts as a trigger. Common culprits include viral infections (such as measles or influenza), bacterial illnesses (like strep throat), or even parasitic infestations. These infections can disrupt immune regulation, setting off a cascade that damages kidney function. While the infection itself may be mild or already resolved, the immune response continues to affect the kidneys, resulting in nephrotic syndrome.
Genetic Causes: Inherited and Spontaneous Mutations
Another significant cause is genetic or hereditary nephrotic syndrome. This form is less common but tends to appear earlier in life, sometimes even in infancy. It occurs when a child inherits a mutated gene from one or both parents that affects kidney development or function. In other instances, the genetic mutation arises spontaneously in the child, with no family history involved.
Recognizing Hereditary Patterns
Conditions like congenital nephrotic syndrome of the Finnish type or mutations in genes such as NPHS1, NPHS2, or WT1 are known to play a role. Genetic testing is often recommended for very young patients or those who don't respond to standard treatments, helping guide long-term management and family counseling.
Secondary Nephrotic Syndrome: Linked to Other Diseases
Secondary nephrotic syndrome develops as a complication of another systemic illness. Unlike primary forms, the kidney damage here is part of a broader disease process affecting multiple organs.
Common Underlying Conditions
Diseases such as systemic lupus erythematosus (SLE)—an autoimmune disorder where the body attacks its own tissues—can directly impact the kidneys, leading to what's known as lupus nephritis. Similarly, Henoch-Schönlein purpura (HSP), a type of blood vessel inflammation often following an infection, can also result in nephrotic-range proteinuria. Other secondary causes include diabetes, certain cancers, and infections like hepatitis B or HIV.
Identifying and treating the primary disease is crucial in managing secondary nephrotic syndrome. Once the underlying condition is under control, kidney function may stabilize or improve significantly.
In summary, while nephrotic syndrome in children presents with similar symptoms regardless of cause, the origins can vary widely—from immune dysregulation and infections to genetic defects and systemic diseases. Early diagnosis, thorough evaluation, and personalized treatment plans are essential for improving outcomes and supporting long-term kidney health in pediatric patients.