Thin basement membrane disease
Encyclopedia
Thin basement membrane disease (TBMD, also known as benign familial hematuria and thin basement membrane nephropathy) is, along with IgA nephropathy
, the most common cause of asymptomatic hematuria
. The only abnormal finding in this disease is a thinning of the basement membrane
of the glomeruli
in the kidneys. Its importance lies in the fact that it has a benign prognosis
, with patients maintaining a normal kidney function throughout their lives.
on urinalysis
. The blood pressure
, kidney function and the urinary protein excretion are usually normal. Mild proteinuria
(less than 1.5 g/day) and hypertension
are seen in a small minority of patients. Frank hematuria
and loin pain should prompt a search for another cause, such as kidney stone
s or loin pain-hematuria syndrome. Also, there are no systemic manifestations, so presence of hearing impairment
or visual impairment
should prompt a search for hereditary nephritis such as Alport syndrome
.
hematuria
, IgA nephropathy
and Alport syndrome
. The history and presentation are helpful in this regard:
A kidney biopsy
is the only way to diagnose thin basement membrane disease. It reveals thinning of the glomerular basement membrane
from the normal 300 to 400 nanometers (nm) to 150 to 250 nm. However, a biopsy
is rarely done in cases where the patient has isolated microscopic hematuria
, normal kidney function and no proteinuria
. The prognosis is excellent in this setting unless the clinical manifestations progress, as occurs in most males and some females with Alport syndrome
and many patients with IgA nephropathy
.
Some individuals with TBMD are thought to be carriers for genes that cause Alport syndrome
.
, though controlled studies are lacking. Treating co-existing hypercalciuria
and hyperuricosuria
will also be helpful in reducing hematuria
.
The molecular basis for thin basement membrane disease has yet to be elucidated fully; however, defects in the gene encoding the a4 chain of type IV collagen have been reported in some families.
. 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.
IgA nephropathy
IgA nephropathy is a form of glomerulonephritis...
, the most common cause of asymptomatic hematuria
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
. The only abnormal finding in this disease is a thinning of the basement membrane
Basement membrane
The basement membrane is a thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs including skin, or the endothelium, which lines the interior surface of blood vessels.- Composition :...
of the glomeruli
Glomerulus
A glomerulus is a capillary tuft that is involved in the first step of filtering blood to form urine.A glomerulus is surrounded by Bowman's capsule, the beginning component of nephrons in the vertebrate kidney. A glomerulus receives its blood supply from an afferent arteriole of the renal...
in the kidneys. Its importance lies in the fact that it has a benign prognosis
Prognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
, with patients maintaining a normal kidney function throughout their lives.
Signs and symptoms
Most patients with thin basement membrane disease are incidentally discovered to have microscopic hematuriaMicroscopic hematuria
Microscopic hematuria is a medical condition in which urine contains small amounts of blood. Blood quantity is too low to change the color of the urine...
on urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
. The blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
, kidney function and the urinary protein excretion are usually normal. Mild proteinuria
Proteinuria
Proteinuria means the presence of anexcess of serum proteins in the urine. The protein in the urine often causes the urine to become foamy, although foamy urine may also be caused by bilirubin in the urine , retrograde ejaculation, pneumaturia due to a fistula, or drugs such as pyridium.- Causes...
(less than 1.5 g/day) and hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
are seen in a small minority of patients. Frank hematuria
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
and loin pain should prompt a search for another cause, such as kidney stone
Kidney stone
A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...
s or loin pain-hematuria syndrome. Also, there are no systemic manifestations, so presence of hearing impairment
Hearing impairment
-Definition:Deafness is the inability for the ear to interpret certain or all frequencies of sound.-Environmental Situations:Deafness can be caused by environmental situations such as noise, trauma, or other ear defections...
or visual impairment
Visual impairment
Visual impairment is vision loss to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive...
should prompt a search for hereditary nephritis such as Alport syndrome
Alport syndrome
Alport syndrome or hereditary nephritis is a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss. Alport syndrome can also affect the eyes . The presence of blood in the urine is almost always found in this condition.It was first identified in a British...
.
Diagnosis
Thin basement membrane disease must be differentiated from the other two common causes of glomerularGlomerulus
A glomerulus is a capillary tuft that is involved in the first step of filtering blood to form urine.A glomerulus is surrounded by Bowman's capsule, the beginning component of nephrons in the vertebrate kidney. A glomerulus receives its blood supply from an afferent arteriole of the renal...
hematuria
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
, IgA nephropathy
IgA nephropathy
IgA nephropathy is a form of glomerulonephritis...
and Alport syndrome
Alport syndrome
Alport syndrome or hereditary nephritis is a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss. Alport syndrome can also affect the eyes . The presence of blood in the urine is almost always found in this condition.It was first identified in a British...
. The history and presentation are helpful in this regard:
- In Alport syndromeAlport syndromeAlport syndrome or hereditary nephritis is a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss. Alport syndrome can also affect the eyes . The presence of blood in the urine is almost always found in this condition.It was first identified in a British...
, there is often a family history of kidney failure, which may be associated with hearing impairmentHearing impairment-Definition:Deafness is the inability for the ear to interpret certain or all frequencies of sound.-Environmental Situations:Deafness can be caused by environmental situations such as noise, trauma, or other ear defections...
. Also, males tend to be more affected as Alport syndrome it is X-linked in most cases. - In IgA nephropathyIgA nephropathyIgA nephropathy is a form of glomerulonephritis...
, episodes of frank hematuriaHematuriaIn medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
are more common, and a family history is less common.
A kidney biopsy
Needle aspiration biopsy
Needle aspiration biopsy , may refer to fine needle aspiration cytology , fine needle aspiration biopsy and fine needle aspiration , is a diagnostic procedure sometimes used to investigate superficial lumps or masses...
is the only way to diagnose thin basement membrane disease. It reveals thinning of the glomerular basement membrane
Glomerular basement membrane
The glomerular basement membrane is the basal laminal portion of the glomerulus. The Glomerular capillary endothelial cells, the GBM and the filtration slits between the podocytes perform the filtration function of the glomerulus, separating the blood in the capillaries from the filtrate that...
from the normal 300 to 400 nanometers (nm) to 150 to 250 nm. However, a biopsy
Needle aspiration biopsy
Needle aspiration biopsy , may refer to fine needle aspiration cytology , fine needle aspiration biopsy and fine needle aspiration , is a diagnostic procedure sometimes used to investigate superficial lumps or masses...
is rarely done in cases where the patient has isolated microscopic hematuria
Microscopic hematuria
Microscopic hematuria is a medical condition in which urine contains small amounts of blood. Blood quantity is too low to change the color of the urine...
, normal kidney function and no proteinuria
Proteinuria
Proteinuria means the presence of anexcess of serum proteins in the urine. The protein in the urine often causes the urine to become foamy, although foamy urine may also be caused by bilirubin in the urine , retrograde ejaculation, pneumaturia due to a fistula, or drugs such as pyridium.- Causes...
. The prognosis is excellent in this setting unless the clinical manifestations progress, as occurs in most males and some females with Alport syndrome
Alport syndrome
Alport syndrome or hereditary nephritis is a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss. Alport syndrome can also affect the eyes . The presence of blood in the urine is almost always found in this condition.It was first identified in a British...
and many patients with IgA nephropathy
IgA nephropathy
IgA nephropathy is a form of glomerulonephritis...
.
Genetics
The molecular basis for thin basement membrane disease has yet to be elucidated fully; however, defects in type IV collagen have been reported in some families.Some individuals with TBMD are thought to be carriers for genes that cause Alport syndrome
Alport syndrome
Alport syndrome or hereditary nephritis is a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss. Alport syndrome can also affect the eyes . The presence of blood in the urine is almost always found in this condition.It was first identified in a British...
.
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 hematuriaHematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
, though controlled studies are lacking. Treating co-existing hypercalciuria
Hypercalciuria
Hypercalciuria or hypercalcinuria is the condition of elevated calcium in the urine. Chronic hypercalcinuria may lead to impairment of renal function, nephrocalcinosis, and renal insufficiency....
and hyperuricosuria
Hyperuricosuria
Hyperuricosuria is a medical term referring to the presence of excessive amounts of uric acid in the urine. Notable direct causes of hyperuricosuria are dissolution of uric acid crystals in the kidneys or urinary bladder, and hyperuricemia...
will also be helpful in reducing hematuria
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
.
The molecular basis for thin basement membrane disease has yet to be elucidated fully; however, defects in the gene encoding the a4 chain of type IV collagen have been reported in some families.
Prognosis
Overall, most people with thin basement membrane disease have an excellent prognosisPrognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
. Some reports, however, suggest that a minority might develop hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
.
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.