IgM nephropathy or immunoglobulin M nephropathy (IgMN) is a kind of idiopathic

glomerulonephritis Glomerulonephritis (GN) is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the ...

that is marked by

IgM Immunoglobulin M (IgM) is the largest of several isotypes of antibodies (also known as immunoglobulin) that are produced by vertebrates. IgM is the first antibody to appear in the response to initial exposure to an antigen; causing it to also ...

diffuse deposits in the glomerular mesangium. IgM nephropathy was initially documented in 1978 by two separate teams of researchers.

Signs and symptoms

Young adults or children with IgM nephropathy typically exhibit

proteinuria Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein, less than 150 mg/day; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become fo ...

hematuria Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with ...

. In people with IgMN,

can vary from

nephrotic syndrome Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes proteinuria, protein in the urine, hypoalbuminemia, low blood albumin levels, hyperlipidemia, high blood lipids, and significant edema, swelling. Other symptoms ...

asymptomatic Asymptomatic (or clinically silent) is an adjective categorising the medical conditions (i.e., injuries or diseases) that patients carry but without experiencing their symptoms, despite an explicit diagnosis (e.g., a positive medical test). P ...

proteinuria.

Causes

The cause of IgM nephropathy is unknown. Several systemic illnesses, including

paraproteinemia Monoclonal gammopathy, also known as paraproteinemia, is the presence of excessive amounts of myeloma protein or monoclonal gamma globulin in the blood. It is usually due to an underlying immunoproliferative disorder or hematologic neoplasms, espe ...

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

systemic lupus erythematosus Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...

(SLE), and Alport's syndrome, can cause

deposits in the glomeruli.

Mechanism

It is yet unknown how IgM nephropathy develops, however it has been proposed that aberrant

T-cell T cells (also known as T lymphocytes) are an important part of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their ce ...

activity or a disruption in mesangial cell immunoaggregate clearance may be involved. Several investigations have found that patients with IgM nephropathy have higher blood

immunocomplex concentrations, which would provide support to the previously indicated idea.

Diagnosis

Light microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...

(LM) on a renal sample reveals variable degrees of

mesangial cell Mesangial cells are specialised cells in the kidney that make up the mesangium of the glomerulus. Together with the mesangial matrix, they form the vascular pole of the renal corpuscle. The mesangial cell population accounts for approximately ...

proliferation or mesangial sclerosis from minute alterations. A small number of instances with crescentic glomerulonephritis (GN) have been documented.

Immunofluorescence Immunofluorescence (IF) is a light microscopy-based technique that allows detection and localization of a wide variety of target biomolecules within a cell or tissue at a quantitative level. The technique utilizes the binding specificity of anti ...

(IF) analysis of

kidney biopsy Renal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, moni ...

specimens shows that

deposits in the

mesangium The glomerulus (: glomeruli) is a network of small blood vessels (capillaries) known as a ''tuft'', located at the beginning of a nephron in the kidney. Each of the two kidneys contains about one million nephrons. The tuft is structurally suppor ...

have a granular or diffuse appearance. While there may be traces of other

immunoglobulins An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that cause di ...

besides

, significant

deposition is typically indicative. Certain investigations have also revealed the existence of complement fragments, such as C3 or C1q.

References

External links

National Kidney Federation

NephCure
{{Glomerular disease Kidney diseases