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Nephrotic Syndrome

Nephrotic syndrome is primarily a pediatric disorder and is 15 times more common in children than adults.

 

The incidence is 2-3/100,000 children per year.

 

Majority of affected children will have steroid-sensitive minimal change disease.

 

The characteristic features of nephrotic syndrome are: Q

  1. heavy proteinuria (>3.5 g/24 hr in adults or 40 mg/m2/hr in children) ,
  2. hypoalbuminemia (<2.5 g/dL),
  3. edema, and
  4. hyperlipidemia. 

Etiology.

  1. Most children (90%) with nephrotic syndrome have a form of the idiopathic nephrotic syndrome.
  2. Causes of idiopathic nephrotic syndrome include minimal change disease (85%), mesangial proliferation (5%), and focal segmental glomerulosclerosis (10%).
  3. The remaining 10% of children with nephrotic syndrome have secondary nephrotic syndrome related to syste-mic or glomerular diseases such as membranous nephropathy or membranoproliferative glomerulonephritis

Nephrotic Syndrome in Children Due to Genetic Disorders of the Podocyte (Latest Question)
 

GENE

NAME

LOCATION

INHERITANCE

RENAL DISEASE

STEROID-RESISTANT NEPHROTIC SYNDROME

NPHS1

Nephrin

19q13.1

Recessive

Finnish-type congenital nephrotic syndrome

NPHS2

Podocin

1q25

Recessive

FSGS

FSGS1

α-actinin-4 (αACTN4)

19q13

Dominant

FSGS

FSGS2

Unknown

11q21–22

Dominant

FSGS

WT1

Wilms tumor-suppressor gene

11p13

Dominant

Denys-Drash syndrome with diffuse mesangial sclerosis Frasier's syndrome with FSGS

LMX1B

LIM-homeodomain protein

9q34

Dominant

Nail-patella syndrome

SMARCAL1

SW1/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1

2q35

Recessive

Schimke immuno-osseous dysplasia with FSGS[*]

STEROID-RESPONSIVE NEPHROTIC SYNDROME

Unknown

Unknown

Unknown

Recessive

MCNS

   

Mechanism: Mechanism of edema formation in nephrotic syndrome massive urinary protein loss leads to hypoalbuminemia, which causes a decrease in the plasma oncotic pressure and transudation of fluid from the intravascular compartment to the interstitial space.
 

The reduction in intravascular volume decreases renal perfusion pressure, activating the renin-angiotensin-aldosterone system, which stimulates tubular reabsorption of sodium.
 

The reduced intravascular volume also stimulates the release of antidiuretic hormone, which enhances the reabsorption of water in the collecting duct.

 

In the nephrotic state, serum lipid levels (cholesterol, triglycerides) are elevated for two reasons. Hypoalbuminemia stimulates generalized hepatic protein synthesis, including synthesis of lipoproteins. In addition, lipid catabolism is diminished, as a result of reduced plasma levels of lipoprotein lipase, related to increased urinary losses of this enzyme.

 


Table: Characteristic features of two groups of nephrotic syndrome.

 

 

Clinical Features -

 

Patient usually presents with insidious onset of generalized edema, without a decrease in urine output. Patient may complain of passing frothy urine due to presence of protein.

 

Treatment

  1. Bed – rest
  2. If GFR > 60 ml/min, no dietary restriction required. If GFR < 60 ml/min dietary protein restriction of 0.8 gm/kg/d + 1 gm proteinuria
  3. Diuretics relieve oedema but do not treat the underlying disorder. Overzealous use of diuretics should be avoided as the patients are often intravascularly depleted and may precipitate prerenal failure. 

Table: Definition :
 

Remission

Urine albumin nil or trace (or proteinuria < 4 mg/m2h) for 3 consecutive days

Relapse

Urine albumin 3+ or 4+ (or proteinuria >40 mg/m2/h) for 3 consecutive days, having been in remission previously.

Frequent relapses

Two or more relapses in six months of initial response, or more than three relapses in any twelve months.

Steroid dependence

Two consecutive relapses when on alternate day steroids or within 14 days of its discontinuation

Steroid resistance

Absence of remission despite therapy with 4 weeks of daily prednisolone in a dose of 2 mg/kg per day.

 

 Description: scan0013

 

Fig: Management of patients with steroid sensitive nephrotic syndrome.

 

Complications

  1. Venous thrombosis and pulmonary embolism (urinary loss of antithrombin III, low plasma volume, increased clotting factors II, V, VII, VIII and X)
  2. Infections (pneumococcal peritonitis)
  3. Hypercholesterolemia (atherosclerosis, xanthomata)
  4. Hypovolemia and renal failure
  5. Loss of specific binding proteins, e.g. transferrin, thyroid – binding globulin.




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