The amount of Immunoglobulin A (IgA) ranks just behind that of IgG in the serum of fit people, and IgA takes up to 10% to 20 % of all serum immunoglobulin. It could be subclassified into serum IgA and secretory IgA in respects of immune function. Serum IgA exists in the serum and takes amount of 85%of total IgA. However, it does not work its immune function specifically in the serum. Secretory IgA can be found in secretion liquid, such as saliva, tears, colostrums, secretion liquid in the nose and bronchus, gastrointestinal fluid, urine, sweat, and etc. Secretory IgA is a major antibody in local anti-infectious immunity for the mucous membrane, and is also called as local antibody in the mucous membran
IgA nephropathy (IgAN), also known as Berger's disease is a special type of glomerulonephritis，and it occurs more commonly to young adults. Usually, there will be infections of upper respiratory tracts before the first onset. The featured pathological changes include hyperplasia of mesangium and large amount of immune complex deposited in mesangium, which could be seen as IgA deposit in visible Mesangial cells by immunofluorescence test.
Pathological changes differ greatly in extent. Earlier pathological changes are slight, presenting focal changes, and only small amount of glomerulus have mild broadening and periodic proliferations. Focal and proliferatie lesions would progress to focal sclerosis. Some lesions are quite obvious with diffuse mesangial proliferations, or crescents occasionally. The most distinguishing features are IgA deposit in visible mesangial cells by immunofluorescence test.
IgA nephropathy (IgAN) is chronic glomerulus disease with same immunopathological characters caused by multiple aetiologies. In clinical practice, 40% to 45% of the patients have gross urine or microscopic hematuria; 35% to 40% of the patients have microscopic hemtauria(Hematuria and Kidney Disease) and albuminuria; the rest have nephrotic syndrome and kidney failure.
Relevant factors affecting the prognosis of IgA nephropathy (IgAN):
(1) Male patients have poor prognosis with elderly onset.
(2) Poor prognosis with persistent microscopic hemtauria and albuminuria.
(3) Poor prognosis with moderate or severe albuminuria which would progress to renal dysfunction. But IgA nephropathy (IgAN) patients with symptoms of nephrotic syndrome have better prognosis, if they have good response to glucocorticoid treatment and mild pathological lesions in the renal tissues.
(4) Poor prognosis if the patients have hypertension, especially for those who have severe hypertension hard to control.
