(See also Overview of Nephritic Syndrome Overview of Nephritic Syndrome Nephritic syndrome is defined by hematuria, variable degrees of proteinuria, usually dysmorphic red blood cells (RBCs), and often RBC casts on microscopic examination of urinary sediment. Often... read more .)
Thin basement membrane disease is a type of nephritic syndrome Overview of Nephritic Syndrome Nephritic syndrome is defined by hematuria, variable degrees of proteinuria, usually dysmorphic red blood cells (RBCs), and often RBC casts on microscopic examination of urinary sediment. Often... read more . It is hereditary and usually transmitted in autosomal dominant fashion. Not all genetic mutations have been characterized, but in some families with thin basement membrane disease there is a mutation in the type IV collagen alpha-4 gene. Prevalence is estimated to be 5 to 9%.
Symptoms and Signs
Most patients are asymptomatic and are incidentally noted to have microscopic hematuria on routine urinalysis, although mild proteinuria and gross hematuria are occasionally present. Renal function is typically normal, but a few patients develop progressive renal failure for unknown reasons. Recurrent flank pain, similar to that in immunoglobulin A nephropathy, Immunoglobulin A Nephropathy Immunoglobulin A (IgA) nephropathy is deposition of IgA immune complexes in glomeruli, manifesting as slowly progressive hematuria, proteinuria, and, often, renal insufficiency. Diagnosis is... read more 
is a rare manifestation.
Diagnosis
Clinical evaluation
Sometimes renal biopsy
Diagnosis is based on family history and findings of hematuria without other symptoms or pathology, particularly if asymptomatic family members also have hematuria. Renal biopsy Renal biopsy Biopsy of the urinary tract requires a trained specialist (nephrologist, urologist, or interventional radiologist). Indications for diagnostic biopsy include unexplained nephritic or nephrotic... read more is unnecessary but is often done as part of a hematuria evaluation. Early on, thin basement membrane disease may be difficult to differentiate from Alport sydrome Alport Syndrome Alport syndrome is a genetically heterogeneous disorder characterized by nephritic syndrome (ie, hematuria, proteinuria, hypertension, eventual renal insufficiency) often with sensorineural... read more 
because of histologic similarities. Molecular genetic analysis can help differentiate these 2 diseases.
Treatment
For frequent gross hematuria, flank pain, or proteinuria, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs)
Long-term prognosis is excellent, and no treatment is necessary in most cases. Patients with frequent gross hematuria, flank pain, or proteinuria (eg, urine protein/creatinine ratio of > 0.2) may benefit from ACE inhibitors or ARBs, which may lower intraglomerular pressure.
