Description

Nephrotic Syndrome Overview Nephrotic syndrome is a kidney disorder characterized by a group of signs and symptoms that result from damage to the glomeruli, the filtering units of the kidneys. This condition leads to excessive protein loss in the urine, low blood protein levels, swelling (edema), and high cholesterol. Key Features of Nephrotic Syndrome Proteinuria: The hallmark of nephrotic syndrome is the loss of large amounts of protein in the urine, typically greater than 3.5 grams per day. The main protein lost is albumin, which leads to low levels of albumin in the blood. Hypoalbuminemia: Low levels of albumin in the blood due to its loss in urine. Albumin helps maintain the balance of fluids in the body, so when it's low, fluid can leak out of the blood vessels into surrounding tissues, causing edema. Edema: Swelling, especially in the feet, ankles, legs, and around the eyes (periorbital edema), is a common feature. Severe edema can also involve the abdomen (ascites) or pleural spaces (pleural effusion). Hyperlipidemia: Elevated levels of cholesterol and triglycerides in the blood are commonly seen in nephrotic syndrome. This is partly due to the liver increasing production of lipoproteins in response to low albumin levels. Hypercoagulability: There is an increased risk of blood clot formation due to changes in clotting factors that can occur with nephrotic syndrome. Causes of Nephrotic Syndrome Nephrotic syndrome can be caused by various underlying conditions, which are typically classified into primary and secondary causes. Primary Causes (Kidney-specific): Minimal Change Disease (MCD): The most common cause in children and a significant cause in adults. It leads to podocyte injury (cells in the glomerulus), but with minimal changes visible under a microscope. It responds well to corticosteroids. Focal Segmental Glomerulosclerosis (FSGS): A disease that causes scarring (sclerosis) of the glomeruli. FSGS can be primary or secondary to conditions like hypertension or obesity. It is less responsive to steroids and may progress to kidney failure. Membranous Nephropathy: An autoimmune disorder where the immune system attacks the glomerular basement membrane, leading to protein leakage. It is more common in adults and may be associated with malignancy or infections. IgA Nephropathy (Berger’s Disease): A condition where deposits of the immunoglobulin A (IgA) antibody accumulate in the glomeruli, causing inflammation and damage. It may present with hematuria, but proteinuria can also be present. Secondary Causes (Systemic Diseases or Other Conditions): Diabetic Nephropathy: A long-term complication of diabetes that can lead to nephrotic syndrome, especially in type 1 diabetes. Systemic Lupus Erythematosus (SLE): Lupus can cause immune complex deposition in the kidneys, leading to nephrotic syndrome. Amyloidosis: Abnormal protein deposits (amyloid) can accumulate in the kidneys and cause nephrotic syndrome. Infections: Certain infections, like HIV, hepatitis B, or malaria, can lead to nephrotic syndrome. Drugs: Some medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), lithium, or gold, can trigger nephrotic syndrome. Malignancies: Some cancers, particularly lymphoma or solid tumors, may be associated with nephrotic syndrome. Diagnosis To diagnose nephrotic syndrome, the following tests are commonly performed: Urinalysis: To detect proteinuria (typically >3.5 grams/day), often showing "frothy" urine due to high protein content. Blood Tests: Low serum albumin and high cholesterol levels. Kidney function is assessed by measuring creatinine and the estimated glomerular filtration rate (eGFR). 24-hour Urine Collection: To quantify the protein excretion in a full day. Kidney Biopsy: In many cases, a kidney biopsy is performed to determine the underlying cause of nephrotic syndrome, especially when the cause is unclear or when there is no response to initial therapy.