Immunoglobulin A Nephropathy

The most common manifestations are persistent or recurrent macroscopic hematuria or asymptomatic microscopic hematuria with mild proteinuria. Flank pain and low-grade fever may accompany acute episodes. Other symptoms are usually not prominent.

Gross hematuria usually begins 1 or 2 days after a febrile mucosal (upper respiratory, sinus, enteral) illness, thus mimicking acute postinfectious glomerulonephritis Postinfectious Glomerulonephritis (PIGN) Postinfectious glomerulonephritis occurs after infection, usually with a nephritogenic strain of group A beta-hemolytic streptococcus. Diagnosis is suggested by history and urinalysis and confirmed... read more , except the onset of hematuria is earlier (coinciding with or immediately after the febrile illness). When this occurs with an upper respiratory illness, it is sometimes referred to as synpharyngitic hematuria.

Rapidly progressive glomerulonephritis Rapidly Progressive Glomerulonephritis (RPGN) Rapidly progressive glomerulonephritis is acute nephritic syndrome accompanied by microscopic glomerular crescent formation with progression to renal failure within weeks to months. Diagnosis... read more is the initial manifestation in < 10% of patients.

Diagnosis is suggested by any of the following:

When manifestations are moderate or severe, diagnosis is confirmed by biopsy.

Urinalysis demonstrates microscopic hematuria, usually with dysmorphic red blood cells (RBCs) and occasionally RBC casts. Mild proteinuria (< 1 g/day) is typical and may occur without hematuria; nephrotic syndrome Overview of Nephrotic Syndrome Nephrotic syndrome is urinary excretion of > 3 g of protein/day due to a glomerular disorder plus edema and hypoalbuminemia. It is more common among children and has both primary and secondary... read more develops in ≤ 20%. Serum creatinine level is usually normal.

Renal biopsy shows granular deposition of IgA and complement (C3) on immunofluorescent staining in an expanded mesangium with foci of segmental proliferative or necrotizing lesions. Importantly, mesangial IgA deposits are nonspecific and also occur in many other disorders, including immunoglobulin A–associated vasculitis Immunoglobulin A–Associated Vasculitis (IgAV) Immunoglobulin A–associated vasculitis (formerly called Henoch-Schönlein purpura) is vasculitis that affects primarily small vessels. It occurs most often in children. Common manifestations... read more , cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic fibrosis that has resulted in widespread distortion of normal hepatic architecture. Cirrhosis is characterized by regenerative nodules surrounded by dense... read more , inflammatory bowel disease Overview of Inflammatory Bowel Disease Inflammatory bowel disease (IBD), which includes Crohn disease and ulcerative colitis, is a relapsing and remitting condition characterized by chronic inflammation at various sites in the gastrointestinal... read more , celiac disease Celiac Disease Celiac disease is an immunologically mediated disease in genetically susceptible people caused by intolerance to gluten, resulting in mucosal inflammation and villous atrophy, which causes malabsorption... read more , psoriasis Psoriasis Psoriasis is an inflammatory disease that manifests most commonly as well-circumscribed, erythematous papules and plaques covered with silvery scales. Multiple factors contribute, including... read more , HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more , lung cancer Overview of Lung Tumors Lung tumors may be Primary Metastatic from other sites in the body Primary tumors of the lung may be Malignant (see table Classification of Primary Malignant Lung Tumors) read more , and several connective tissue disorders.

Glomerular IgA deposition is a primary feature of immunoglobulin A–associated vasculitis, and it may be indistinguishable from IgA nephropathy based on biopsy specimens, leading to speculation that immunoglobulin A–associated vasculitis may be a systemic form of IgA nephropathy. However, immunoglobulin A–associated vasculitis Immunoglobulin A–Associated Vasculitis (IgAV) Immunoglobulin A–associated vasculitis (formerly called Henoch-Schönlein purpura) is vasculitis that affects primarily small vessels. It occurs most often in children. Common manifestations... read more is clinically distinct from IgA nephropathy, usually manifesting as hematuria, purpuric rash, arthralgias, and abdominal pain.

Other serum immunologic tests are usually unnecessary. Complement concentrations are usually normal. Plasma IgA concentration may be elevated, and circulating IgA-fibronectin complexes are present; however, these findings are not helpful diagnostically.

IgA nephropathy usually progresses slowly; renal insufficiency and hypertension develop within 10 years in 15 to 20% of patients. Progression to end-stage renal disease Chronic Kidney Disease Chronic kidney disease (CKD) is long-standing, progressive deterioration of renal function. Symptoms develop slowly and in advanced stages include anorexia, nausea, vomiting, stomatitis, dysgeusia... read more occurs in 25% of patients after 20 years. When IgA nephropathy is diagnosed in childhood, prognosis is usually good. However, persistent hematuria invariably leads to hypertension, proteinuria, and renal insufficiency. Risk factors for progressive deterioration in renal function include the following:

Normotensive patients with intact renal function (serum creatinine < 1.2 mg/dL [106.08 micromol/L]) and only mild proteinuria (< 0.5 g/day) usually are not treated beyond angiotensin inhibition (with an ACE inhibitor or ARB) and omega-3 fatty acids (fish oil). Patients with renal insufficiency or more severe proteinuria and hematuria are usually offered treatment, which ideally should be started before significant renal insufficiency develops.