The hallmark of glomerular disorders is proteinuria Proteinuria Proteinuria is protein, usually albumin, in urine. High concentrations of protein cause frothy or sudsy urine. In many renal disorders, proteinuria occurs with other urinary abnormalities (eg... read more , which is often in the nephrotic range (≥ 3 g/day).
Glomerular disorders are classified based on urine changes as those that manifest predominantly with
Nephrotic-range proteinuria and nephrotic urine sediment (fatty casts, oval fat bodies, but few cells or cellular casts)
Hematuria, usually in combination with proteinuria (which may be in the nephrotic range); the red blood cells (RBCs) are usually dysmorphic and often there are RBC or mixed cellular casts (nephritic urine sediment)
Nephrotic syndrome Overview of Nephrotic Syndrome Nephrotic syndrome is urinary excretion of > 3 g of protein/day due to a glomerular disorder plus edema and hypoalbuminemia. It is more common among children and has both primary and secondary... read more is nephrotic urine sediment plus edema and hypoalbuminemia (typically with hypercholesterolemia and hypertriglyceridemia).
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 is nephritic urine sediment with or without hypertension, elevated serum creatinine, and oliguria.
Several glomerular disorders typically manifest with features of both nephritic and nephrotic syndromes. These disorders include, but are not limited to, fibrillary and immunotactoid glomerulopathies Fibrillary and Immunotactoid Glomerulopathies Fibrillary and immunotactoid glomerulopathies are rare conditions defined pathologically by organized deposition of nonamyloid microfibrillar or microtubular structures within the renal mesangium... read more , membranoproliferative glomerulonephritis Membranoproliferative Glomerulonephritis Membranoproliferative glomerulonephritis is a heterogeneous group of disorders that share mixed nephritic and nephrotic features and microscopic findings. They mostly affect children. Cause... read more (GN), and lupus nephritis Lupus Nephritis Lupus nephritis is glomerulonephritis caused by systemic lupus erythematosus (SLE). Clinical findings include hematuria, nephrotic-range proteinuria, and, in advanced stages, azotemia. Diagnosis... read more .
The pathophysiology of nephritic and nephrotic disorders differs substantially, but their clinical overlap is considerable—eg, several disorders may manifest with the same clinical picture—and the presence of hematuria or proteinuria does not itself predict response to treatment or prognosis.
Disorders tend to manifest at different ages (see table Glomerular Disorders by Age and Manifestations Glomerular Disorders by Age and Manifestations ), although there is much overlap. The disorders may be
Secondary (see tables Causes of Glomerulonephritis Causes of Glomerulonephritis and Causes of Nephrotic Syndrome Causes of Nephrotic Syndrome )
Serum creatinine level and urinalysis
A glomerular disorder is usually suspected when screening or diagnostic testing reveals an elevated serum creatinine level and abnormal urinalysis (hematuria with or without casts, proteinuria, or both). Approach to the patient involves distinguishing predominant-nephritic from predominant-nephrotic features and identifying likely causes by patient age, accompanying illness (see table Glomerular Disorders by Age and Presentation Glomerular Disorders by Age and Manifestations and table Causes of Nephrotic Syndrome Causes of Nephrotic Syndrome ), and other elements of the history (eg, time course, systemic manifestations, family history).
Renal biopsy Causes of Nephrotic Syndrome is indicated when diagnosis is unclear from history or when histology influences choice of treatment and outcomes (eg, lupus nephritis Lupus Nephritis Lupus nephritis is glomerulonephritis caused by systemic lupus erythematosus (SLE). Clinical findings include hematuria, nephrotic-range proteinuria, and, in advanced stages, azotemia. Diagnosis... read more ).