Difference Between Glomerulonephritis and Nephrotic Syndrome

A syndrome is a combination of medical problems that show the existence of a particular disease or mental condition. The two ailments discussed here are renal diseases seen commonly in the clinical setup. The main difference between Glomerulonephritis and Nephrotic Syndrome is the degree of proteinuria. In nephrotic syndrome, there is a massive proteinuria with the protein loss usually over 3.5g/day, but in glomerulonephritis, there is only a mild proteinuria where the daily protein loss is less than 3.5g.

CONTENTS

1. Overview and Key Difference
2. What is Glomerulonephritis 
3. What is Nephrotic Syndrome
4. Similarities Between Glomerulonephritis and Nephrotic Syndrome
5. Side by Side Comparison – Glomerulonephritis vs Nephrotic Syndrome in Tabular Form
6. Summary

What is Glomerulonephritis?

Glomerulonephritis (nephritic syndrome) is a condition characterized mainly by hematuria (i.e. the presence of red blood cells in urine) along with other symptoms and signs such as azotemia, oliguria and mild to moderate hypertension.

Glomerulonephritis can be categorized into main two groups based on the duration of the disease.

1. Acute Proliferative Glomerulonephritis
2. Rapidly Progressive Glomerulonephritis

Acute Proliferative Glomerulonephritis

This condition is histologically characterized by the influx of leukocytes along with the proliferation of glomerular cells. These events occur as a response to the immune complexes deposited in the renal parenchyma.

The typical presentation of acute proliferative glomerulonephritis is a child complaining of fever, malaise, nausea and smoky urine, few weeks after a streptococcal throat or skin infection. Although it is most often seen after an infection, it can also be because of non-infectious causes.

Pathogenesis

Exogenous or endogenous antigens
⇓
Bind with the antibodies produced against them
⇓
Antigen- antibody complexes get deposited in the glomerular capillary walls
⇓
Provoke an inflammatory response
⇓
Proliferation of glomerular cells and influx of leukocytes

Morphology

• Under the light microscope enlarged, hyper cellular glomeruli can be observed.
• Globular deposits of IgG and C3, accumulated along the glomerular basement membrane can be observed using an immunofluorescence microscope.

Clinical Course

A majority of the patients recover after proper treatments. A very few number of cases can progress into the more severe, rapidly progressive glomerular nephritis.

Treatment

Conservative therapy to maintain the water and sodium balance

Rapidly Progressive Glomerulonephritis (RPGN)

As the name suggests, this condition is characterized by the rapid and progressive loss of renal functions because of a severe damage to the glomeruli.

Pathogenesis

Rapidly Progressive Glomerulonephritis can be seen in many systemic diseases such as good pasture’s syndrome, IgA nephropathy, Henoch Schonlein purpura and microscopic polyangiitis. Although the pathogenesis is related to the immune complexes, the exact mechanism of the process is unclear.

Morphology

Macroscopically enlarged, pale kidneys having petechial hemorrhages on the cortical surface can be observed.  Microscopically, the most helpful feature to differentiate rapidly progressive glomerulonephritis from any other condition is the presence of “crescents” which are formed by the proliferation of parietal cells and the migration of monocytes and macrophages into the renal tissue.

Clinical Course

Rapidly progressive glomerulonephritis can be a life threatening condition if not treated properly. The patient can end up with severe oliguria due to the deterioration of the renal parenchyma.

Treatment

RPGN is treated with steroids and cytotoxic drugs.

What is Nephrotic Syndrome?

The hall mark feature of nephrotic syndrome is the presence of massive proteinuria with the daily loss of proteins exceeding 3.5g. In addition to the massive proteinuria, hypoalbuminemia with plasma albumin levels less than 3g/dl, generalized edema, hyperlipidemia and lipiduria also can be observed.

The pathophysiology behind these clinical features can be explained using the flow chart given below.

(Edema is aggravated by the sodium and water retention due to the action of renin)  

There are three major clinically important conditions that manifest as nephrotic syndrome.

1. Membranous nephropathy
2. Minimal change disease
3. Focal segmental glomerulosclerosis

Membranous Nephropathy

The defining histological feature of membranous nephropathy is the thickening of the glomerular capillary wall. This happens as a result of the accumulation of Ig containing deposits.

Membranous nephropathy is most commonly associated with the use of certain drugs such as NSAIDS, malignant tumors, and systemic lupus erythematosus.

Pathogenesis

Pathogenesis differs according to the underlying condition, but immune complexes are almost always involved.

Morphology

Under the light microscope, glomeruli may appear normal during the initial stages but with the disease progression uniform, diffuse thickening of the capillary walls can be observed. In the more advanced cases, segmental sclerosis may also be evident.

Minimal Change Disease

In comparison to the other disease conditions discussed here, minimal change lesion can be considered as a harmless disease entity. An important point to be noticed is the inability to use light microscopy in the identification of this condition.

Morphology

As previously mentioned glomeruli appear normal under the light microscope. The effacement of foot processes of podocytes can be observed easily using an electron microscope.

Focal Segmental Glomerulosclerosis (FSGS)

In this condition, not all glomeruli are affected and even if a glomerulus is affected only a part of that affected glomerulus undergoes sclerosis. That is why this disease is called the focal segmental glomerulosclerosis.

Pathogenesis

Pathogenesis is due to some complex immunologically mediated reactions.

Morphology

Use of light microscopy in the identification of FSGS is not advisable because during the early stages there is a chance of missing the affected region of the specimen and arriving at a wrong diagnosis.

Use of an electron microscope will show the effacement of the foot processes of podocytes along with the plasma proteins that have been deposited segmentally along the capillary wall. These deposits can sometimes occlude the capillary lumen.

Treatment of Nephrotic Syndrome

Mode of treatment varies according to the underlying disease conditions, comorbidities, age and drug compliance of the patient.

What are the Similarities Between Glomerulonephritis and Nephrotic Syndrome?

• In both conditions, proteinuria and edema can be seen.
• Both affect the renal parenchyma.

What is the Difference Between Glomerulonephritis and Nephrotic Syndrome?

Summary – Glomerulonephritis vs Nephrotic Syndrome

Both nephritic syndrome and nephrotic syndrome are renal disorders which share few common symptoms. But the fine line which makes them two separate disease entities is drawn across the degree of proteinuria, If the protein loss is higher than 3.5g/day then it is nephrotic syndrome and vice versa. It is very important for a clinician to have a good understanding of the difference between Glomerulonephritis and Nephrotic Syndrome.

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Reference:

1. Kumar, Vinay, Stanley Leonard Robbins, Ramzi S. Cotran, Abul K. Abbas, and Nelson Fausto. Robbins and Cotran pathologic basis of disease. 9th ed. Philadelphia, Pa: Elsevier Saunders, 2010. Print.

Image Courtesy:

1. “Post-infectious glomerulonephritis – very high mag” By Nephron – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Minimal Change Disease Pathology Diagram” By Renal_corpuscle.svg: M•Komorniczak -talk- (polish Wikipedist)derivative work: Huckfinne (talk) – Renal_corpuscle.svg (CC BY-SA 3.0) via Commons Wikimedia