Henoch-Schonlein purpura nephritis is kidney damage secondary to allergic purpura and the most common secondary nephritis in children. The reported incidence of kidney involvement in allergic purpura varies, with domestic data showing 25-60% of pediatric patients having urinary abnormalities during the course of the disease. If kidney biopsy is used as the criterion, over 90% of children with allergic purpura exhibit varying degrees of kidney involvement. Kidney involvement directly affects prognosis. During the acute phase of allergic purpura, aside from rare fatalities due to gastrointestinal involvement or complications, the prognosis mainly depends on the type and severity of kidney involvement. In the acute phase, death may occur due to rapidly progressive nephritis or progression to chronic renal insufficiency, or the condition may slowly advance to chronic renal insufficiency.

bubble_chart Etiology

Pathological changes

The manifestations of lesions are diverse. The main manifestation is mesangial proliferative glomerulonephritis, with segmental exacerbation visible. Sometimes segmental fibrinoid necrosis of capillary loops is observed, often accompanied by crescent formation. Currently, the Meadow classification is commonly referenced, dividing it into the following six types: Type I: Minimal changes. Type II: Simple mesangial proliferative changes. Type III: Focal (IIIa) and diffuse (IIIb) mesangial proliferation, with crescent formation (less than 50% of glomeruli involved). Type IV: Focal (IVa) and diffuse (IVb) mesangial proliferation, with crescent formation (50-75% of glomeruli involved). Type V: Focal (Va) and diffuse (Vb) mesangial proliferation, with crescent formation (more than 75% of glomeruli involved). Type VI: Mesangial capillary nephritis. Immunofluorescence shows diffuse granular IgA fluorescence in the mesangial area, accompanied by complement C3 and properdin deposition.

bubble_chart Diagnosis

Clinical Diagnosis

The diagnosis can be made when a child presents with both the clinical manifestations of Henoch-Schönlein purpura (HSP) and nephritis. HSP can occur in all age groups but is most common in school-aged children, featuring skin lesions of allergic purpura. Two-thirds of cases present with gastrointestinal symptoms (abdominal pain, varying degrees of hematochezia) and joint swelling or pain. Renal involvement typically occurs within the first month of onset, with most cases presenting as hematuria, often accompanied by proteinuria. The severity of renal involvement varies. Mild cases may only show hematuria without significant edema or hypertension, and normal renal function. Some patients present similarly to acute nephritis, with hematuria, edema, and hypertension, after which the edema and hypertension gradually subside, but urinary abnormalities persist for a longer duration. The third presentation is secondary nephrotic syndrome. The fourth manifests as rapidly progressive nephritis, progressing to renal failure within months. Additionally, some cases may follow a chronic nephritis course.

﹝Treatment﹞

(1) Rest: Bed rest is advisable during the acute phase, which helps alleviate skin purpura and relieve joint symptoms. (2) Removal of disease cause: Identify and eliminate allergens as much as possible, such as administering antibiotics for infection foci and discontinuing food or drugs for those with a history of allergies. (3) Symptomatic treatment: Provide antispasmodic and analgesic measures for gastrointestinal symptoms (e.g., intramuscular or intravenous injection of 654-2), and consider fasting and fluid therapy if necessary. Closely monitor for potential surgical complications (e.g., intussusception, intestinal necrosis, perforation, etc.). (4) Dipyridamole or other anticoagulant therapy: May help reduce or mitigate renal involvement. (5) Adrenal corticosteroids: Effective in relieving acute-phase gastrointestinal symptoms and arthralgia. Commonly used prednisone at 1–2 mg/(kg·d), administered orally in divided doses, can be tapered and discontinued once symptoms are controlled. Most scholars observe that this treatment does not appear to aid in preventing renal involvement. For rapidly progressive nephritis, methylprednisolone pulse therapy may be administered (see rapidly progressive nephritis). For nephrotic syndrome, hormone therapy similar to that for primary nephrotic syndrome may be applied, with dose reduction after 8 weeks and switching to alternate-day oral prednisone maintenance for an extended period. Other immunosuppressants (e.g., cyclophosphamide) may also be added. (6) Replacement therapy: For chronic renal failure unresponsive to conservative treatment, replacement therapies such as dialysis or kidney transplantation may sometimes be necessary.

bubble_chart Differentiation

The diagnosis of typical cases is not difficult, but sometimes it needs to be differentiated from acute post-streptococcal glomerulonephritis, vasculitis syndromes (including polyarteritis nodosa, Wegener's granulomatosis, allergic vasculitis, etc.), lupus nephritis, and others.