Idiopathic Nephrotic Syndrome

Nephrotic syndrome is a clinical syndrome characterized by abnormal massive loss of protein, mainly albumin, from the blood into the urine with resulting hyperlipidemia, edema, and various complications. This occurs due to damage to the glomeruli, the tiny blood vessels networks in the kidneys responsible for filtering waste and excess substances from the blood to form urine.

The glomeruli have a filtration barrier that prevents large molecules such as proteins from entering the urine. When this filtration barrier is impaired, as is the case in nephrotic syndrome, proteins such as albumin can enter the urine. This leads to a decrease in proteins, especially albumin, in the blood, which can result in edema (swelling) and other associated symptoms due to decreased osmcotic pressure (pressure that keeps fluid in the blood vessels).

► The first indication of nephrotic syndrome in children is the swelling of the face which later progresses to the entire body, adults present more with dependent edema. Other common features are fatigue and loss of appetite.

The term "idiopathic" indicates that the cause of this condition is unknown. It primarily affects children between 2 and 7 years of age and is the most common cause of nephrotic syndrome. Idiopathic nephrotic syndrome (INS) accounts for 15–30% of adult glomerulopathies and >70% of all nephrotic syndrome cases in children. The histopathological presentations involve minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), diffuse mesangial sclerosis, and membranous nephropathy. The common features are based on podocyte alterations with protein expression or localization defects, actin cytoskeleton remodeling, or intracellular signaling pathway activation which all lead to a disturbance of glomerular filtration barrier properties. In idiopathic nephrotic syndrome there are no significant deposits of certain proteins (immunoglobulins) or immune system markers (complement) when examined under immunofluorescence.

Primary (idiopathic) nephrotic syndrome, results from an abnormality of glomerular permeability which may be primary with a disease-specific to the kidneys. Common primary causes of nephrotic syndrome are intrinsic kidney diseases, such as membranous nephropathy, minimal-­change nephropathy, and focal glomerulosclerosis. In children, minimal change disease is the most common cause of nephrotic syndrome. Notably, an episode of infectious diseases, particularly the upper respiratory tract, an allergic reaction, and more rarely, an insect bite or vaccination are important triggering factors for the disease.

Congenital/hereditary neprotic syndrome, occurs because of genetic defects in podocyte-related molecules, such as podocin or nephrin, as podocytes are important differentiated cells of the kidney glomerulus that are essential for the integrity of the kidney filter.

Secondary Nephrotic Syndrome, which is triggered by a variety of other underlying diseases and occurs secondary to congenital infections, diabetes, systemic lupus erythematosus, neoplasia, certain viral infections or drug use.

Prednisone is the first-line treatment to reduce proteinuria and control inflammation. The treatment duration and dose may vary based on the response.

If the patient does not respond to corticosteroids or experiences frequent relapses, other immunosuppressive drugs like mycophenolate mofetil, calcineurin inhibitors or cyclophosphamide may be prescribed.

Diuretics are used to manage edema and fluid retention.

 A low-sodium diet may be recommended to control edema and blood pressure.

Due to increased susceptibility to infections, vaccination and prompt treatment of infections are essential.

Regular check-ups are necessary to monitor kidney function, proteinuria, and side effects of medications.