What is Membranous Nephropathy?

Membranous nephropathy is a medical condition involving the malfunction of the kidneys. It is one of the forms of nephrotic syndrome, which is a term applied to a type of kidney damage that includes secretions of large amounts of proteins. Membranous nephropathy is actually one of the syndrome's most common versions, with adults being the main victims of the disease.

In several cases, the membranous nephrotic syndrome occurs when the glomeruli in the kidneys thicken, resulting in inflammation. Glomeruli are small blood vessels essential for filtering the waste and excess fluid in blood to form urine. The reason for the glomerular thickening, however, remains unknown. Exposure to toxins such as mercury, infections such as syphilis and hepatitis, and cancers such as leukemia and melanoma increase the risk of contracting membranous nephropathy.

The membranous nephrotic syndrome is sometimes referred to as membranous glomerulonephritis. The latter condition, however, is named after its classification as a nephritis syndrome. This means that patients with such a condition have red blood cells and excess serum proteins in their urine, called hematuria and proteinuria, respectively. By contrast, membranous nephropathy, as a nephrotic syndrome, only has proteinuria.

The presence of serum proteins in urine gives it a foamy appearance, so foamy urine is one of the symptoms of membranous nephropathy. People with the syndrome also tend to urinate excessively, especially during night time. Other signs include a loss of appetite, weight gain, fatigue, high blood pressure and swelling that can occur at any part of the body.

Doctors usually administer kidney tests to determine the presence of membranous nephropathy. They may remove cells or tissues from the kidney to examine them, check for swelling on the body, conduct a urinalysis to assess the level of protein or blood in the urine, or do a blood test for infectious diseases. Other diagnostic methods include anti-nuclear antibodies, blood urea nitrogen (BUN), creatinine and cryoglobulin tests.

Since there is no cure for membranous nephropathy, physicians employ a variety of treatment methods to at least slow it down and reduce its symptoms. Patients can also use angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) to combat high blood pressure, which is a main factor in kidney damage. A diet low in salt and combined with water-pill intake is helpful for reducing the swelling. While there are some cases in which membranous nephropathy disappears, other patients are not so lucky, with the worst-case scenario involving end-stage renal disease.