What Is Nephrotic Syndrome? Understanding Causes, Risk Factors, and Treatment Approaches

Nephrotic syndrome is a collection of symptoms and laboratory findings that indicate significant kidney dysfunction. It is primarily diagnosed through the presence of massive proteinuria, defined as more than 3.5 grams of protein excreted in the urine over a 24-hour period, combined with hypoalbuminemia—a serum albumin level below 3.0 g/dL. These core clinical markers signal damage to the glomeruli, the filtering units of the kidneys, leading to excessive protein leakage into the urine. While nephrotic syndrome can affect individuals at any age, its underlying causes vary significantly across different age groups and populations.

Common Causes Across Different Age Groups

In adolescents and younger individuals, nephrotic syndrome is often linked to primary glomerular diseases such as minimal change disease, which may be triggered by viral infections. Notably, certain systemic infections like hepatitis B or hepatitis C can directly contribute to immune-mediated kidney injury. Additionally, conditions such as Henoch-Schönlein purpura (HSP), an autoimmune vasculitis affecting small blood vessels, are known to induce secondary forms of nephrotic syndrome in this demographic.

Autoimmune and Systemic Triggers in Young Adults

Among young adult women, one of the most prevalent causes is lupus nephritis, a kidney complication arising from systemic lupus erythematosus (SLE). This autoimmune disorder leads to inflammation and damage within the renal system, often resulting in severe protein loss and impaired kidney function. Due to hormonal and immunological factors, females are disproportionately affected, making early screening crucial for timely intervention.

Metabolic and Malignancy-Related Causes in Older Adults

As people age, the etiology of nephrotic syndrome shifts toward chronic metabolic conditions and malignancies. Diabetes mellitus, particularly type 2 diabetes, is a leading contributor, causing diabetic nephropathy through prolonged hyperglycemia-induced glomerular damage. Other metabolic disorders, such as amyloidosis, where abnormal proteins accumulate in organs including the kidneys, also play a significant role. Furthermore, hematologic cancers—such as multiple myeloma and lymphoma—are increasingly recognized as potential triggers, even in the absence of solid tumors.

Secondary vs. Primary Nephrotic Syndrome: Why Etiology Matters

Distinguishing between primary (idiopathic) kidney disease and secondary causes is essential for effective treatment planning. A thorough diagnostic workup—including blood tests, urinalysis, imaging, and sometimes kidney biopsy—is necessary to identify whether the condition stems from intrinsic kidney pathology or results from another systemic illness. Treating the root cause—whether it's controlling blood sugar in diabetics, managing autoimmune activity in lupus, or addressing an underlying infection—can dramatically improve outcomes.

Potential Complications and Their Impact on Prognosis

Patients with nephrotic syndrome face several serious complications that can worsen their prognosis if left unmanaged. Infections are common due to the loss of immunoglobulins in urine and weakened immune defenses. Malnutrition may develop as a result of persistent protein loss, leading to muscle wasting and fluid retention. Perhaps most dangerous is the increased risk of thromboembolic events, such as deep vein thrombosis or pulmonary embolism, caused by a hypercoagulable state associated with altered blood protein levels.

Early recognition, accurate diagnosis, and comprehensive management—including medication (like corticosteroids or immunosuppressants), dietary adjustments, and supportive care—are vital in slowing disease progression and improving quality of life. With proper medical attention, many patients can achieve remission or maintain stable kidney function over time.