Nephrotic syndrome

Diagnostic criteria and clinical presentation

The classic diagnosis is based on four key manifestations (a laboratory triad plus a clinical sign):

• Massive proteinuria (reaches 20–30 g/day, characterized by high selectivity—mostly albumin is lost).
• Hypoalbuminemia (it is the degree of albumin decrease that determines the severity of the condition and hypovolemia).
• Hyperlipidemia (increase in total cholesterol, triglycerides, and low-density lipoproteins against the background of a drop in high-density lipoproteins).
• Edematous syndrome.

Clinically, patients appear pale, skin is cold, and diuresis is reduced (oliguria). Edema is generalized and can rapidly progress to anasarca with fluid accumulation in body cavities (ascites, hydrothorax, hydropericardium). In the classic variant, the syndrome is "pure"—that is, it proceeds without arterial hypertension and hematuria (although in rare cases, transient microhematuria or blood pressure spikes due to compensatory sodium retention are possible).

Pathogenesis of edema formation

Edematous syndrome in this pathology develops in a vicious circle due to a series of hemodynamic shifts:

1. Due to damage to the filtration barrier, albumin is lost in the urine.
2. The blood plasma oncotic pressure drops.
3. Fluid tends to move into tissues with a higher oncotic pressure, leaving the vascular bed.
4. Hypovolemia (decrease in circulating blood volume) is formed.
5. The body tries to compensate for the volume deficit: the renin-angiotensin-aldosterone and sympathetic systems are activated, antidiuretic hormone production increases, and natriuretic peptide is suppressed.
6. The kidneys begin to retain sodium and water, leading to "dilutional hypoalbuminemia" and an even greater increase in edema.

Life-threatening complications

Massive shifts in metabolism and hemodynamics can lead to critical conditions:

• Hypovolemic shock: sharp drop in blood pressure, tachycardia, abdominal pain, and vomiting against the background of a catastrophic blood volume deficit.
• Prerenal acute kidney injury: develops due to renal tissue ischemia during systemic hypovolemia.
• Thrombosis (usually venous): hemoconcentration combines with the loss of natural anticoagulants in the urine (proteins C and S, antithrombin III). The risk increases with the use of diuretics and bed rest.
• Severe infections: massive loss of immunoglobulins, T-cell dysfunction, and glucocorticoid therapy create pronounced secondary immunodeficiency.

Principles of therapy

The standard approach to treating minimal change disease does not require a biopsy at the start (it is only needed for atypical presentation, age under 1 year, or resistance).

The basis of pathogenetic therapy is glucocorticoids (prednisolone). Treatment is divided into three stages:

• Induction: 4–6 weeks of daily intake.
• Consolidation: 4–6 weeks of alternate-day intake.
• Tapering: slow dose reduction until complete cessation (the entire course takes 4–5 months).

Over 90% of children respond to such therapy (steroid-sensitive variant). If there is no effect after 8 weeks, steroid resistance is diagnosed, and the patient is switched to steroid-sparing regimens (alkylating agents, calcineurin inhibitors, monoclonal antibodies). Loop diuretics, strict bed rest, and a salt-free diet with water balance monitoring are used as symptomatic treatment.

Class and exam questions

What else to study on this topic

• Pathogenesis of immune (T-cell) and genetic damage to the glomerular filter
• Secondary forms of nephrotic syndrome and their triggers
• Reserve drugs for steroid resistance (mycophenolate mofetil, rituximab)
• Strategies for renoprotection and thrombosis prevention in NS

Other topics in "Chapter 8. Kidney and Urinary Tract Diseases"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.