DefinitionNephrotic syndrome Is a clinical syndrome associated with proteinuria in the nephrotic range (3.5mg/m2/24hrs), edema and hyperlipidemia.
Nephrotic syndrome is not due to inflammatory processes but due to direct action of the membrane attack unit of complement on the glomerulus.
Clinical suspicionIt should be suspected when a patient presents with generalized oedema, protein detected in urine, hypoalbuminemia.
DiagnosisThe diagnosis maybe established with proteinuria in the nephrotic range alone without the other criteria.
1. Proteinuria > 3.5 g/m2/day:
On detection of protein in urine a 24 hour urinary protein test is in order. There are two cut off values for this test: 1. increased urinary protein <1.5g/day; this is refered to as isolated proteinuria. 2. >3.5g/day; this establishes nephrotic syndrome.
As albumen in serum is lost through the kidneys, the liver increases its production of albumen and concomitantly increases the production of cholesterol.
4. Oedema: resulting from loss of intravascular fluid to the extravascular space due decreased intravascular oncotic pressure (decreased albumen).
However, the presence of proteinuria in the nephrotic range (3.5g/day) establishes the diagnosis.
Differential diagnosis: proteinuria
CausesOnce the diagnosis of nephrotic syndrome is established the cause of the syndrome is sought in order to treat accordingly.
Nephrotic syndrome with active sediment (mixed nephrotic/ nephritic)This denotes the presence of RBC casts (active sediment). Causes include:
1ry glomerular diseases as MPGN (main cause), and 2ry glomerular diseases as SLE (most common presentation of SLE), vasculitis such as Henoch Schonlein purpura, mixed essential cryoglobulinemia.
Nephrotic syndrome with bland sediment (Pure nephrotic)1ry glomerular diseases such as MCNS, Membranous glomerulonephritis, Focal glomerulosclerosis. As well as 2ry glomerular diseases that result from Diabetes (Klemelsteli-Wilson syndrome) and amyloidosis.
TreatmentTreatment of nephrotic syndrome depends primarily on the cause, however, it frequently involves the use the glucorticoids given over long periods of time. Especially in cases of minimal change disease. Here the role of steroids is to suppress the autoimmune basis for this disease. The use of cytotoxic agents maybe required in some cases (e.g. cyclophosphamide).
Dietary salt control, treatment of hypertension and hypercholestrolemia is also recommended. ACE inhibitors, in addition to controlling blood pressure have also been found to decrease the protein loss. Diuretics may help control the edema and the hypertension.