Pathogenesis

PATHOGENESIS

It had been suspected that the genetic defect in thin basement membrane nephropathy would be similar to that in hereditary nephritis (Alport syndrome), since patients with the latter group of disorders also have thin basement membranes early in the course of the disease. This hypothesis has been confirmed in families in which thin basement membrane nephropathy was due to heterozygous defects in COL4A3 or COL4A4, the genes that encode for the alpha-3 and alpha-4 chains of type IV collagen  The entire group of disorders encompassing TBMN and Alport syndrome has been called the Type IV Collagen Nephropathies. - cited from uptodate

             

DIET

Diet for a Person With Thin Basement Membrane Syndrome

By Suzanne Robin           

Photo Credit Snakebite Productions/Digital Vision/Getty Images

Although thin basement membrane disease sounds like something that would affect the lower levels of your house, it's actually an often-inherited disorder that affects the kidneys. This disorder, also called benign familial hematuria, affects between 5 and 9 percent of Americans, according to the Merck Manual. In most cases, no treatment is necessary, although you may develop high blood pressure or, in rare instances, kidney failure. If you have a severe strain of the disease, following a kidney-friendly diet may help avoid complications.

Normal Dietary Restrictions

If you have this disorder, the glomerular basement membrane, one of the tissue layers in your kidney, ranges from 150 to 225 nanometers instead of a normal 300 to 400 nanometers, according to the Merck Manual. Normally, this does not cause any significant kidney problems. If you have no symptoms of thin basement membrane disease -- and most people don't -- beyond minute amounts of blood or protein in your urine, you do not need to follow any dietary restrictions.

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Watching Sodium Intake

The American Heart Association suggests that everyone limit his sodium intake to no more than 2,300 milligram per day, especially people with an increased risk of developing high blood pressure. If you develop hypertension, the medical term for high blood pressure, as a complication of this disease, you may need to limit your sodium intake to less than the recommended dose of 2,300 milligrams of sodium per day and your doctor may prescribe a 1,500 milligram per day diet. Excess sodium intake can raise your blood pressure. Work with a dietitian to determine exactly what you can and can't eat, but limit processed foods, which often contain large amounts of sodium, and don't add extra salt while cooking or at the table.

Kidney Failure Diet

If your disease progresses, you may need to limit phosphorus, protein and possibly potassium, if your potassium levels are high. Dairy products and meats, especially processed meat, contain large amounts of protein and phosphorus. Many vegetables, including potatoes, greens, including spinach, Brussels sprouts and winter squash are high in phosphorus or potassium or both. It's important not to institute dietary changes unless your doctor recommends them and to stay within the limits he prescribes. Working with a dietitian helps you plan a diet that stays within your limits but that still tastes good and encourages you to eat.

Considerations

Some serious kidney diseases, such as Alport syndrome, start with the same symptoms as thin basement membrane disease. Distinguishing between the two may require a kidney biopsy or more specialized testing. Hearing and vision loss may occur if you have Alport syndrome, which normally affects males more than females. Notify your doctor if you develop hearing or vision loss, since these symptoms may indicate a more serious disorder that requires more stringent dietary restrictions.

Read more: http://www.livestrong.com/article/550871-diet-for-a-person-with-thin-basement-membrane-syndrome/#ixzz22Urh87zN

Read more: http://www.livestrong.com/article/550871-diet-for-a-person-with-thin-basement-membrane-syndrome/#ixzz22UrY1s64

Epidemiology

Epidemiology

TBMN has been reported in all races, although most of the cases thus far have been reported in developed countries. Hematuria has been diagnosed at all ages (8,11,43), and several studies have indicated that the disease is somewhat more common in female than in male individuals, among both children and adults (8,17,18,27,42–47), but other studies have not revealed such findings (26,48–50). Exact prevalence of the disease is difficult to assess, as the diagnosis is made mostly on the basis of persistent hematuria combined with minimal proteinuria, whereas the number of electron microscopic analyses of renal biopsies showing thinned basement membrane have become less common (51). Thus, most of the cases remain undiagnosed. However, the prevalence may be estimated from known frequencies of persistent hematuria in the population and from the number of TBMN cases in archival series of renal biopsies, together with the knowledge of prevalence of autosomal Alport syndrome (51). Several studies have addressed the prevalence of hematuria and persistent hematuria in children and adults (52–56). Persistent hematuria is commonly defined as hematuria that is observed on at least two occasions, and in TBMN, a useful additional criterion could be that these two incidents occurred at least 2 yr apart (51). Persistence of hematuria is important from the point of view of TBMN diagnosis, as it distinguishes from other, more acute renal disorders, such as hematuria associated with streptococcal infections (51). The prevalence of hematuria in children has been estimated to be 1 to 2% (52,53), but the prevalence in adults is not well known (3). According to Wang and Savige (51), persistent hematuria occurs consistently in as much as 6% of both children and adults. On the basis of both direct and indirect approaches, the overall prevalence of TBMN in the population has been estimated to be 1% (3). However, on the basis of observations of frequencies of persistent hematuria, thin basement membrane in renal biopsies, and autosomal recessive Alport syndrome, another estimate indicates a higher prevalence of >1 but <10% (51). When making estimations about the prevalence of TBMN by analyzing incidence of hematuria, one should keep in mind that not all patients who have TBMN have hematuria (or it is intermittent), that some patients with persistent hematuria have other signs of renal impairment (excluding the diagnosis of TBMN), and last that hematuria is not always of glomerular origin. It can be concluded, however, that TBMN is the most common inherited renal disorder.

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Karl Tryggvason and 

Jaakko Patrakka

Under the Microscope

THIN GLOMERULAR  BASEMENT MEMBRANE DISEASE (TMBD)

Under the Microscope

The glomerular basement wall in patients with TBM disease appears thinner.
The image below is taken with an electron microscope. On the left shows a healthy kidney filter basement wall, and on the right shows a basement wall in a person with TBM disease.

Image showing the glomerular basement wall in a healthy person	Image showing the glomerular basement wall in a patient with TBM

Prognosis

THIN GLOMERULAR  BASEMENT MEMBRANE DISEASE (TMBD)

Prognosis 

Overall, most people with thin basement membrane disease have an excellent prognosis Some reports, however, suggest that a minority might develop hypertension

Thin basement membrane disease may co-exist with other kidney diseases, which may in part be explained by the high prevalence of thin basement membrane disease. (wiki)

Treatment

THIN GLOMERULAR  BASEMENT MEMBRANE DISEASE (TMBD)

Treatment

Most patients with thin basement membrane disease need only reassurance. Indeed, this disease was previously referred to as "benign familial hematuria" because of its usually benign course. Angiotensin converting Enzyme Inhibitors have been suggested to reduce the episodes of hematuria. Treating co- existing hypercaliuria and hyper uricosia will also be helpful reducing hematuria 

Genetics

THIN GLOMERULAR  BASEMENT MEMBRANE DISEASE (TMBD)

Genetics:
The molecular basis for thin basement membrane disease has yet to fully understood; however, defects in the gene encoding the a4 chain of type IV collagen have been reported in some families.