Lipoid nephrosis, more commonly known as minimal change disease, is a term describing a form of glomerulonephritis that can result in nephrotic syndrome and progress to end-stage renal disease in rare cases. The disorder is usually seen in children, when proteinuria, and less commonly hypertension and edema, present as main clinical features. The diagnosis rests on clinical criteria and histological findings after performing a biopsy.
Lipoid nephrosis, frequently termed minimal change disease (MCD), is by far the most common cause of nephrotic syndrome in children. More than 90% of pediatric cases arise on the grounds of MCD, while 10-15% of adult cases, in whom the diagnosis is most frequently made in the third and fourth decades of life, occurs due to MCD   . The principal feature of lipoid nephrosis is the sudden onset of proteinuria accompanied by edema in a previously healthy individual, with urine protein levels reaching as high as 10 g/24h   . Additional manifestations, although less common, include hematuria, hypertension, and renal insufficiency, and they are more frequently encountered among adults   . Spontaneous remission of proteinuria, usually after 8-12 weeks , is seen in approximately 30% of pediatric cases , which may be one of the distinguishing features of lipoid nephrosis. However, relapses are quite frequently observed, even after appropriate therapy with corticosteroids, and are reported to occur even 10 years after the initial presentation  . Moreover, many patients become steroid-dependent in order to prevent further deterioration of kidney function. End-stage renal disease is the most feared complication of lipoid nephrosis.
Clinical suspicion toward lipoid nephrosis can only be made if sufficient information is obtained through a detailed patient history and a thorough physical examination. Data regarding the onset of symptoms and their recurrence and the potential presence of edema and/or hypertension must be further assessed through laboratory testing. Blood urea nitrogen (BUN) and creatinine levels, as well as urinalysis, with a particular emphasis on the extent of protein levels in urine, are mandatory steps in the workup. Serum electrolyte levels, particularly sodium and potassium, should be evaluated as well. A 24-hour collection of urine is often recommended to determine the exact loss of protein, and the term "selective proteinuria" is used to describe the selective urinary loss of albumin , one of the main features of lipoid nephrosis. Despite the fact that clinical criteria and findings from urinalysis may provide enough clues to make the diagnosis, a definite confirmation is achieved after biopsy, which may not be always indicated due to its risks. The absence of immunoglobulin deposits (characteristic of other types of glomerulonephritis that have an underlying immunologic mechanism of disease) and preserved glomeruli are main features on light microscopy, whereas diffuse effacement of foot processes of podocytes are typical findings on electron microscopy   .