Understanding Kidney Impacts of Henoch-Schönlein Purpura

Henoch-Schönlein purpura (HSP) is an IgA-mediated vasculitis causing a rash, joint pain and possible kidney disease. While typically self-limiting, persistent renal inflammation called HSP nephritis can threaten long term function. This article details kidney risks and the role of monitoring to prevent complications.

Introduction to Kidney Involvement in Henoch-Schönlein Purpura

First described in 1837 by physician Eduard Heinrich Henoch, HSP predominantly affects children, manifesting as the classic tetrad of palpable purpura on the lower legs, arthralgias, abdominal pain and kidney abnormalities. The peak age is 4-6 years.

Up to 50% of pediatric HSP cases develop some degree of acute kidney inflammation or nephritis, ranging from microscopic blood and protein to hypertension, acute nephritis or nephrotic syndrome. While transient at onset for many, a subset suffer progressive loss of kidney function over months to years if the immune-mediated injury recurs unchecked.

Tight surveillance and prompt treatment of flares aims to safeguard nephrons and ultimate wellbeing. Understanding risk factors and patterns of progression guides prevention in this complex disorder with varied outcomes.

Pathophysiology of HSP Nephritis

The primary underlying trigger for HSP remains unclear. Various infectious agents and other stimuli are hypothesized to provoke abnormal glycosylation of IgA antibodies, causing IgA-containing immune complexes to deposit extensively in tissues rather than clearing normally. These complexes activate complement and inflammatory cascades upon binding small blood vessel walls, including the renal glomerular capillaries which filter blood to form urine.

Specifically in the kidney, the deposited complexes elicit cellular proliferation and scarring reactions from mesangial cells and podocytes constituting the glomerular tuft. Protein-rich fluid and red blood cells then leak into the urine. Cytokines released further recruit white cells and fibroblasts laying fibrous tissue, progressively impairing filtration. This sclerotic process mediated by continuing or recurrent IgA deposition drives chronic kidney dysfunction termed HSP nephritis.

Incidence and Risk Factors for HSP Kidney Disease

Reported frequencies of nephritis complicating HSP vary widely in literature from 20-80% across pediatric cohorts. Multiple large case series indicate boys have modestly higher incidence than girls. Children under age 6 years tend to experience more renal involvement likely related to immature immunity provoking exaggerated inflammation.

Ethnic patterns emerge as well – Asian children have documented lower nephritis rates around 35%, contrasting with Caucasians approaching 60% in some analyses. Family history may indicate genetic contributions. Recurrent flares also heighten susceptibility to cumulative kidney damage, especially within the first 6 months.

Presentation and Nature of HSP Kidney Abnormalities

Hematuria and Proteinuria

Microscopic or visible blood alongside excess protein in the urine represents the most common renal presentation. This leakage of cells and serum components indicates disruption of the glomerular filter. Dipstick testing readily identifies both. May be intermittent initially but tends to persist in nephritis.

Nephrotic Syndrome

Heavy proteinuria exceeding 40 mg/m2/hour or clinical edema signals severe glomerular inflammation akin to primary nephrotic disorders. Hypoalbuminemia and dyslipidemia accompany protein wasting. Requires prompt treatment to avoid rapid deterioration.

Acute Nephritis

Gross hematuria, hypertension and acute kidney injury with rising creatinine marks severe inflammation with extensive crescent formation damaging filtration capacity. Hospitalization for intensive multi-modal therapy is standard to limit permanent loss.

Chronic Kidney Disease

Despite treatment, ongoing immunologic injury can silently replace functional renal tissue with scar tissue gradually over years. Hypertension and uremia then eventually emerge once a critical mass of nephrons is lost. Dialysis and transplant may become necessary despite initial subtle presentation.

Outcomes of HSP Renal Involvement

With appropriate therapy guided by vigilant monitoring for relapse, studies estimate over 90% of children have favorable long term kidney prognosis after HSP. Proteinuria and hematuria generally resolve within 4-6 weeks of treatment, paralleling improvements in other disease manifestations.

However, up to 5% still progress to chronic kidney disease or end-stage renal failure over varied intervals, occasionally abrupt following a devastating crescentic presentation. In one cohort with baseline nephrotic-range proteinuria, over 50% developed chronic renal sequelae. Once severe kidney dysfunction occurs the course tends to be relentless without immunomodulation, plasma exchange or dialytic support.

Adults overall have worse renal outcomes – up to 30-66% progress to chronic kidney disease within 5 years of onset in various analyses. Deaths in untreated or late-diagnosed adult HSP cases result primarily from kidney complications rather than direct vasculitis impacts.

Monitoring Plan to Detect Renal HSP Relapses

As seemingly mild HSP can lead to deferred nephritis, urinalysis screening for hematuria/proteinuria is advised for all patients at diagnosis, even without symptomatic kidney issues. This establishes a baseline for tracking disease trajectory.

The American College of Rheumatology recommends:

• Urine testing every 3 months for the first year, then twice yearly.
• Annual visits long term to monitor blood pressure and kidney function.
• More frequent assessment for patients with prior nephritis.

Detecting recurrence early while still mild optimizes preserving long-term kidney health through prompt re-treatment. Patients should be educated on potential signs of relapse like new rash, joint pains, edema or foaminess of urine indicative of protein loss.

Treatment Approach for HSP Renal Manifestations

Supportive Care

Ensuring good fluid intake, nutrition, blood pressure control and avoiding nephrotoxic drugs promotes kidney stability between flares. Smoking cessation aids vasculitis remission. Urinary alkalinization may ease dysuria and obstruction from bleeding clots.

Corticosteroids

Oral prednisolone rapidly suppresses severe inflammation, best when introduced early in under 6 months duration when reversible. Prolonged high dose glucocorticoids risk side effects.

Immunosuppressants

For aggressive or refractory courses, steroid-sparing agents like mycophenolate mofetil, cyclophosphamide or rituximab calm immunologic activity. Plasma exchange benefits select cases.

Blood Pressure Medications

Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) counter proteinuria progression and hypertension secondary to diseased kidneys.

Contagiousness and Transmission Risk of HSP

HSP itself has not been shown to be contagious. The vasculitis is understood to represent an aberrant autoimmune reaction confined to the affected individual, rather than spreading between people. However, preceding infections often trigger initial cases. Avoiding exposures to sick contacts during disease flares may help prevent reactivation. Blood products from donors with active HSP should not be utilized given theoretical concerns.

Living with Henoch-Schönlein Purpura Nephritis

Coping with HSP nephritis poses unique emotional challenges layered upon the anxiety of the initial diagnosis. Fear of renal decline despite standard treatments being maxed out contributes to frustration. Parents struggle watching children endure relapse symptoms and procedures. Community support groups and therapists provide validation and teach resilience during the uncertain course.

Encouraging patient self-advocacy equips families to partner closely through shared decision making at each twist and turn. While daunting initially, most children emerging from the HSP journey without permanent sequelae ultimately lead full active lives. Maintaining hope and self-care helps counter the stresses navigating relapsing-remitting illness.

FAQs About HSP Kidney Impacts

Below are answers to frequently asked questions regarding the renal manifestations of this vasculitis:

Is HSP contagious?

No, HSP itself has not been shown to spread infection between people. The immune-mediated flare results from internal processes rather than transmission of external contagious particles. However, preceding infections often kickstart cases. Avoiding sick contacts may prevent reactivation.

How does HSP kidney disease differ in children compared to adults?

• Risk: Adult HSP less often includes the classic skin rash but more frequently affects the kidneys – over 50% get nephritis.
• Course: Renal prognosis is worse in adults with up to 35% progressing to end-stage disease within 5 years despite treatment.
• Manifestations: Children often have isolated microscopic urine abnormalities that may resolve quickly. Adults tend to suffer heavier proteinuria, hypertension and acute nephritis leading to rapid decline.
• Timing: Pediatric renal relapse generally occurs within 6 months of onset. Later recurrence years out is more common with adult HSP.

Is kidney transplant an option for HSP renal failure?

Yes, transplantation can be curative for ESRD from HSPN after optimizing vasculitis activity control. Isolated reports suggest electron microscopy of explanted kidneys showing chronic changes without ongoing IgA deposition favors better outcome. However, HSP recurrence in the transplant causing loss of the new graft is a major risk needing immunosuppression. Overall long-term success still lags other diagnoses.

What precautions should HSP patients take to protect their kidneys?

Preventing irreversible nephron loss warrants lifestyle vigilance:

• Take medications consistently, avoid nephrotoxins.
• Control blood pressure optimally with ACEI/ARB regimens.
• Restrict protein if spilling large amounts.
• Maintain ideal weight for height.
• Stay active but avoid exhaustion.
• Reduce sodium intake if retaining fluid.
• Stay current with provider visits and urinalysis testing.

Can pregnancy worsen kidney prognosis in females with previous HSP nephritis?

Yes, the hemodynamic and immunologic stresses of pregnancy can trigger nephritic flares resulting in permanent glomerular loss. Risk elevates with baseline kidney dysfunction. Pursuing conception should involve nephrology guidance on managing vasculitis activity beforehand and careful monitoring of renal function throughout gestation to preserve outcomes.

Conclusion and Takeaway Points

In summary:

• Up to half of Henoch-Schönlein purpura patients develop acute kidney inflammation termed HSP nephritis.
• Persisting immunologic renal injury causes progressive dysfunction even years later in a subset.
• Tight surveillance and early re-treatment of flares aims to safeguard long-term kidney health and function.
• Education on risks and self-monitoring empowers patients to actively partner in care.
• HSP itself does not appear contagious between people based on current evidence.
• Continued research on the variable natural history and optimal prevention strategies is still needed.

While usually self-limited initially, the relapsing-remitting nature of HSP with renal involvement mandates judicious long term tracking to preserve wellbeing. Patient awareness and engagement facilitates shared disease management.

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