Most Common and Serious Complications of Primary Nephrotic Syndrome
Primary nephrotic syndrome (PNS) is a kidney disorder characterized by excessive protein loss in the urine, low blood protein levels, high cholesterol, and significant swelling. While the condition itself presents major health challenges, it's the associated complications that often pose the greatest risks to patients. Understanding these complications is essential for early detection, effective management, and improved long-term outcomes.
1. Acute Kidney Injury: A Sudden Decline in Renal Function
One of the most critical complications of primary nephrotic syndrome is acute kidney injury (AKI). This condition can develop rapidly due to several interrelated factors. The hallmark of PNS—massive proteinuria—can lead to tubular obstruction as proteins accumulate in the renal tubules, impairing normal kidney function.
In addition, severely reduced serum albumin levels (hypoalbuminemia) result in decreased intravascular volume. This hypovolemia reduces blood flow to the kidneys, compromising perfusion and increasing the risk of ischemic damage. The use of diuretics, commonly prescribed to manage edema, may further exacerbate volume depletion if not carefully monitored.
Patients with profound hypoalbuminemia are particularly vulnerable to AKI. Clinically, this manifests as oliguria (reduced urine output) and a sharp rise in serum creatinine. However, some individuals may experience non-oliguric AKI, where creatinine levels increase despite maintained urine output—making diagnosis more challenging without regular lab monitoring.
2. Thromboembolic Events: Increased Risk of Blood Clots
Hypercoagulability is a well-documented feature of nephrotic syndrome, significantly raising the risk of thrombosis. In response to protein loss, the liver increases production of clotting factors, including fibrinogen and other pro-coagulant proteins, while simultaneously decreasing anticoagulant proteins like antithrombin III.
High-Risk Patients: Those with Severe Hypoalbuminemia
Individuals with serum albumin levels below 25 g/L—especially those with membranous nephropathy or minimal change disease—are at substantially greater risk. These patients often require prophylactic anticoagulation therapy to prevent life-threatening events.
The most dangerous consequence of hypercoagulability is pulmonary embolism (PE), which occurs when a dislodged clot travels to the lungs. PE can be fatal if not promptly diagnosed and treated. Deep vein thrombosis (DVT) in the legs is a common precursor, underscoring the importance of vigilant clinical surveillance and preventive strategies.
3. Infections: A Leading Cause of Morbidity and Mortality
Infection remains a leading cause of hospitalization and death among patients with primary nephrotic syndrome. Multiple factors contribute to immune compromise:
- Excessive loss of immunoglobulins in the urine weakens humoral immunity
- Impaired complement system function reduces pathogen clearance
- Widespread use of corticosteroids and immunosuppressive agents further suppresses immune defenses
Prolonged, high-dose steroid therapy increases susceptibility to bacterial, viral, and fungal infections. Respiratory tract infections, particularly pneumonia, are among the most common and potentially fatal. Encapsulated bacteria such as Streptococcus pneumoniae pose a special threat due to impaired opsonization.
Preventive measures—including vaccination (e.g., pneumococcal and influenza vaccines), infection screening, and judicious use of immunosuppressants—are crucial components of comprehensive care.
In summary, while primary nephrotic syndrome affects kidney filtration directly, its systemic complications—acute kidney injury, thromboembolism, and severe infections—are what often dictate patient prognosis. Early recognition, proactive monitoring, and individualized treatment plans are key to minimizing risks and enhancing quality of life for those living with this complex condition.