Types of IgAN

The Foundation for IgA Nephropathy

Types of IgAN

IgAN is a variable disease which can be roughly described using the following categories. However, it is important to note that these are not really diagnostic terms, and there can be some overlap between them.

Chronic IgAN. This refers to the typical, slowly-progressive type of IgAN that may be relatively stable for years (basically the common IgAN that adults usually have). Approximately 30 percent of these patients will progress to end-stage renal failure in 10 to 25 years. Some believe that everyone with this pattern of IgAN would eventually progress to end-stage if they lived long enough. Since the disease has only been known as a separate entity since 1968, these statistics may not be completely reliable, given that the oldest possible official diagnosis of IgAN could not have taken place until only 3 decades ago. Enough time may not have passed since 1968 for all patients diagnosed to have reached end-stage. Chronic IgAN is usually treated conservatively. Even when IgAN first presents more acutely, it usually continues as a chronic condition to some degree, after the acute episode resolves.

Acute IgAN. This is a term that can be used when a person, often a child, teenager or young adult, first presents with an acute glomerulonephritis (or nephritic syndrome), which eventually turns out to be IgAN (diagnosed by biopsy). The most obvious symptom is visible blood in the urine. This often also presents with heavy proteinuria (protein in the urine), and if this is heavy enough, the patient may be said to have nephrotic syndrome. Many people with IgAN experience recurring "flare-ups", or episodes of visible blood in their urine, every time they get an upper respiratory infection of some kind. The term acute IgAN may sometimes be used in this context. These acute phases may come and go, but the underlying disease process of chronic IgAN usually remains. It is common for visible blood in the urine to gradually become microscopic, and for heavy proteinuria to go down to a more acceptable level (although this may require the use of medications). It is also possible to develop acute nephritic symptoms on top of existing chronic IgAN. It's possible for someone to develop acute renal failure (ARF) to the point of needing dialysis, usually in conjunction with the disease HSP

Rapidly-progressive IgAN. Sometimes referred to as crescentic IgAN. This pattern is a more aggressive form which progresses to end-stage renal failure within months or more commonly, a few years (5 years or less). The finding of extensive crescents in the biopsy specimens may point to this diagnosis. It is not known why some people have this more aggressive pattern of IgAN. Rapidly-progressive IgAN is often treated more aggressively than the chronic one. This pattern may also be accompanied by an abnormally high amount of IgG antibodies in the urine.

Pediatric IgAN. This is not really a separate form of IgAN, however, since it may behave or be treated differently in children, it is included here as a separate category. IgAN in children usually first appears acutely, that is, it presents as an acute glomerulonephritis (this is often associated with the associated disease HSP). Children with IgAN are often treated with oral steroids (sometimes on an alternate-day basis to minimize the side effects) in an attempt to halt the disease. Often, the disease will appear to go into complete remission once the hematuria and proteinuria have resolved. However, the IgAN may continue as a very mild underlying condition, punctuated by occasional "flare-ups" which are triggered by upper respiratory infections. It is also not clear, but probable that at least a very mild, slowly-progressing or stable chronic IgAN will continue throughout adulthood. Only a repeat biopsy can determine to what extent the mesangial deposits of IgA in the glomeruli have receded in any way, and, if the disease appears to be in remission, there is no value in performing such a repeat biopsy. There are some cases where, either as a decision by the individual nephrologist and parents, or as part of a clinical trial, more aggressive treatment is used with immune system suppressant drugs such as Imuran (azathioprine) or Cellcept (mycophenolate mofetil). Either of these might be used alone or, more usually, together with an oral steroid (usually prednisone, but there are others). It's impossible for any website to suggest any specific treatment, but, we suggest you discuss the advisability of such treatments with your child's doctor. These are more likely to be used when there is persistant, heavy proteinuria. See the entry for HSP below.

Secondary IgAN. Most cases of IgAN are idiopathic. This means that it is a disease on its own. However, a number of other diseases may cause predominant mesangial deposition of IgA in the glomeruli as a secondary effect. This may be referred to as secondary IgAN. It is quite likely that your nephrologist will have excluded other possible causes of IgAN-like symptoms. These are the main ones, but there are up to 30 or more diseases which may be associated with deposition of IgA in the kidneys in some form or another:

Henoch-Schonlein purpura (HSP). HSP is a small blood vessel vasculitis characterized by immunoglobulin A (IgA), C3, and immune complex deposition in arterioles, capillaries, and venules. HSP and IgA nephropathy are somewhat related disorders. Both illnesses have elevated serum IgA levels and identical findings on renal biopsy. However, IgA nephropathy involves primarily young adults (and to a lesser extent older adults), and it predominantly affects only the kidneys. HSP affects mostly children and it may involve the skin and connective tissues, gastrointestinal tract, joints, and scrotum as well as the kidneys. Of the diseases that cause secondary deposition of IgA in the kidneys, only HSP causes renal involvement which, on biopsy, is indistinguishable from that of IgA nephropathy. In fact, IgAN and HSP appear to be different levels of the same disease, with IgAN being more or less only the renal manifestation of HSP, minus the latter disease's other symptoms. If your child develops a reddish or purple-like rash on the lower body, HSP is a possibility, as is renal involvement in the form of IgAN. By the same token, if you are told your child has IgAN, it would be worthwhile asking whether there is any sign of it being secondary to HSP. HSP can sometimes cause reversible acute renal failure (ARF) and may require dialysis treatment. Click here for an external link to medical information about HSP.

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