Nephrotic syndrome
Figure 1. Nephrotic edema.
Figure 2. Nephrotic edema.
NEPHROTIC SYNDROMENEPHROTIC SYNDROME Pathophysiology
- Proteinuria- Hypoalbuminemia- Edema- Hyperlipidemia
Cause (diagnosis and differential diagnosis)- Systemic renal disease
hepatitis B associated glomerulonephritis, Henoch-Schonlein purpura, systemic lupus erythematosus, diatetes mellitus, amyloidosis
- Idiopathic nephrotic syndrome Complications
- Infection- Coagulation disorders- Protein malnutrition and dyslipidemia- Acute renal failure
Pathophysiology
Proteinuria
Proteinuria can be caused by systemic overproduction, tubular dysfunction, or glomerular dysfunction. It is important to identify patients in whom the proteinuria is a manifestation of substantial glomerular disease as opposed to those patients who have benign transient or postural (orthostatic) proteinuria.
Heavy proteinuria (albuminuria)
Figure 3.
Hypoalbuminemia
Hypoalbuminemia is in part a consequences of
urinary protein loss. It is also due to the
catabolism of filtered albumin by the proximal
tubule as well as to redistribution of albumin
within the body. This in part accounts for the
inexact relationship between urinary protein
loss, the level of the serum albumin, and other
secondary consequences of heavy albuminuria .
The salt and volume retention in the NS may occur through at least two different major mechanisms.
In the classic theory, proteinuria leads to hypoalbuminemia, a low plasma oncotic pressure, and intravascular volume depletion. Subequent underperfusion of the kidney stimulates the priming of sodium-retentive hormonal systems such as the RAS axis, causing increased renal sodium and volume retention, In the peripheral capillaries with normal hydrostatic pressures and decreased oncotic pressure, the Starling forces lead to transcapillary fluid leakage and edema .
Edema
In some patients, however, the intravascular volume has been measured and found to be increased along with suppression of the RAS axis. An animal model of unilateral proteinuria shows evidence of primary renal sodium retention at a distal nephron site, perhaps due to altered responsiveness to hormones such as atrial natriuretic factor. Here only the proteinuric kidney retains sodium and volume and at a time when the animal is not yet hypoalbuminemic. Thus, local factors within the kidney may account for the volume retention of the nephrotic patient as well.
Edema
Figure 4.
Hyperlipidemia
Most nephrotic patients have elevated levels of total and
low-density lipoprotein (LDL) cholesterol with low or
normal high-density lipoprotein (HDL) cholesterol .
Lipoprotein (a) [Lp(a)] levels are elevated as well and
return to normal with remission of the nephrotic
syndrome. Nephrotic patients often have a
hypercoagulable state and are predisposed to deep vein
thrombophlebitis, pulmonary emboli, and renal vein
thrombosis.
Cause
Table 2 CAUSES OF THE NEPHROTIC SYNDROME
Table 3a NEPHROTIC SYNDROME ASSOCIATED WITH SPECIFIC CAUSES (“SECONDARY” NEPHROTIC SYNDROME)
Table 3b NEPHROTIC SYNDROME ASSOCIATED WITH SPECIFIC CAUSES (“SECONDARY” NEPHROTIC SYNDROME)
Diagnosis and Differential diagnosis
Initial evaluation of the nephrotic patient
includes laboratory tests to define whether
the patient has primary, idiopathic
nephrotic syndrome or a secondary cause
related to a systemic disease.
Common screening tests include the fasting blood sugar
and glycosylated hemoglobin tests for diabetes, and
antinuclear antibody test for rheumatoid disease, and
the serum complement, which screen for many immune
complex-mediated disease (Table 3), In selected
patients, cryoglobulins, hepatitis B and C serology, anti-
neutrophil cytoplasmic antibodies (ANCAS), anti GBM
antibodies, and other tests may be useful. Once
secondary causes have been excluded, treating the
adult nephrotic patient often requires a renal biopsy to
define the pattern of glomerular involvement.
It leads to a multitude of other consequences ,
such as predisposition to infection and
hypercoagulability. In general, the diseases
associated with NS cause chronic kidney
dysfunction, but rarely they can cause ARF.
ARE may be seen with minimal change disease,
and bilateral renal vein thrombosis.
ComplicationsInfectionCoagulation disordersProtein malnutrition and dyslipidemiaAcute renal failure
Treatment
1. General treatment
2. Symptomatic treatment
(e.g.diuresis to relieve
edema, treating
dyslipidemias,
anticoagulate treatment,
etc.)
3. Immunosupressive
treatment
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