Nephritic syndromes: Pathology review

On the nephrology ward, two people came in with the same symptoms: peripheral and periorbital edema, along with cola-colored urine, arterial hypertension and decreased urine output.

The first person is 10 year old Timmy who had a throat infection two weeks ago.

The second one is 45 year old Dorothy, who also presents with hemoptysis.

Lab tests show that both of them have increased creatinine and BUN.

On urinalysis, there’s hematuria and red blood cell casts in the urine.

A 24-hour protein collection was done and showed that both Timmy and Dorothy had proteinuria, but in both cases it was less than 3.5 grams per day.

Now, both Timmy and Dorothy have nephritic syndrome.

Nephritic syndrome is typically caused by inflammation that damages the glomerular basement membrane, leading to hematuria and red blood cell casts in the urine.

Eventually, this damage can lead to renal failure, where the individual can present with oliguria, arterial hypertension, due to sodium retention, and peripheral and periorbital edema.

Lab tests show high levels of BUN and creatinine and on urinalysis, there’s hematuria, proteinuria and RBC casts in the urine.

A 24-hour protein collection is necessary to quantify how many proteins are lost through urine.

Now, nephritic syndrome can be differentiated from nephrotic syndrome because the proteinuria is generally under 3.5 grams per day, or within the “subnephrotic range”.

In severe cases though, proteinuria can reach over 3.5 grams per day.

In order to determine the cause, a careful history and a kidney biopsy can help diagnose the particular disease.

Okay, let’s start talking about the different disorders that could cause nephritic syndrome.

To make things simpler, we can categorize these into three groups; those caused by type III hypersensitivity, like poststreptococcal glomerulonephritis, IgA nephropathy, and Diffuse proliferative glomerulonephritis; those with multiple potential causes, like membranoproliferative glomerulonephritis, and rapidly progressive glomerulonephritis; and finally, Alport syndrome which is caused by a defect in collagen synthesis.