Symptoms of Henoch-Schönlein Purpura Nephritis in Children

Henoch-Schönlein purpura nephritis (HSPN) is a form of kidney injury that develops as a complication of Henoch-Schönlein purpura (HSP), an immune-mediated small-vessel vasculitis commonly seen in children. This condition primarily affects the skin, joints, gastrointestinal tract, and kidneys, with renal involvement being one of the most critical factors influencing long-term outcomes.

Understanding Henoch-Schönlein Purpura: The Starting Point

HSP typically begins acutely, often triggered by preceding infections—especially upper respiratory tract infections—or exposure to certain allergens such as shellfish or crab. One of the hallmark signs is a distinctive skin rash that usually appears after these triggers. The rash is petechial or purpuric in nature, meaning it results from bleeding under the skin and does not fade when pressed—a key diagnostic clue.

This rash most commonly manifests on the lower extremities, particularly both legs, and tends to be symmetrically distributed. Unlike typical allergic rashes, it's often non-pruritic (not itchy) and may appear raised above the skin surface. While the rash can be alarming for parents, it's usually not painful and resolves without scarring in most cases.

Systemic Involvement Beyond the Skin

While skin lesions are the most visible symptom, HSP is a systemic disease and can affect multiple organ systems. Gastrointestinal involvement occurs in up to 60% of pediatric cases. Children may experience abdominal pain, which can range from mild discomfort to severe cramping. In more serious instances, gastrointestinal bleeding may occur, leading to bloody stools. Rarely, complications like intussusception—a condition where part of the intestine folds into itself—may develop, requiring urgent medical or surgical intervention.

Joint Manifestations: Arthralgia and Arthritis

Another common feature is joint involvement, known as arthralgia or arthritis. Children may suddenly develop swelling and pain in large joints, especially the knees and ankles. This can limit mobility and cause significant discomfort, though it typically resolves without permanent damage. These symptoms often coincide with the appearance of the rash and generally subside within days to weeks.

Kidney Involvement: The Most Critical Complication

The most concerning aspect of HSP is its potential to progress to Henoch-Schönlein purpura nephritis, which affects approximately 20–50% of children with HSP. Renal involvement can vary widely in severity—from isolated microscopic hematuria (blood in the urine detectable only under a microscope) to more severe presentations including proteinuria, nephrotic-range protein loss, or even acute kidney injury.

In milder cases, children may only show persistent blood in the urine, while more severe forms involve significant protein leakage, leading to swelling (edema), low blood protein levels, and high cholesterol—classic features of nephrotic syndrome. In rare but critical situations, some children may present with acute renal failure at onset, necessitating dialysis and intensive management.

When Does Kidney Damage Occur?

One of the most frequently asked questions among parents is: "When should we worry about kidney problems?" Research shows that over 90% of children who develop nephritis do so within four weeks of the initial rash. However, delayed onset of renal symptoms has been documented, sometimes appearing several months later.

Because of this variability, medical guidelines recommend close monitoring of urine parameters—including routine urinalysis for blood and protein—for at least six months following the diagnosis of HSP. If no signs of kidney involvement emerge during this period, the likelihood of future renal complications becomes extremely low.

Diagnosing and Assessing Severity

To accurately assess the extent of kidney damage, a renal biopsy may be necessary, especially in cases with heavy proteinuria or impaired kidney function. This procedure allows doctors to evaluate the degree of inflammation and scarring in the glomeruli—the filtering units of the kidneys—and helps guide treatment decisions.

Early detection and appropriate management are crucial. Treatments may include corticosteroids, immunosuppressive agents, or supportive therapies depending on the severity. With timely intervention, many children recover fully, although a small percentage may experience chronic kidney issues into adulthood.

In summary, while Henoch-Schönlein purpura is often a self-limiting illness, its renal complications require vigilant follow-up. Awareness of the signs—skin rash, abdominal pain, joint swelling, and especially changes in urination—can lead to earlier diagnosis and better outcomes for affected children.