Acute Nephritic Syndrome vs Hematuria

In our reputed recommended Pathology texts, clinical presentation of glomerular diseases usually starts with either nephritic (Robbins’) or nephrotic (Rubin’s) syndrome. As a rule, nephrotic syndrome, a condition commonly seen in clinical settings, is relatively easy to explain, comprehend, and diagnose, therefore I won’t talk about it today.

On the opposite side, nephritic syndrome is not so common, and its full-blown clinical picture is not often seen nowadays. One hundred years ago a patient with acute poststreptococcal glomerulonephritis would present with gross hematuria, hypertension edema, and oliguria, usually followed by azotemia/uremia. Today, for diagnosis of acute nephritic syndrome, presence of only two out of four signs (edema, hematuria, hypertension and oliguria) is required. That means if you have a patient manifesting edema and hematuria, or hematuria and hypertension, you can proceed with the diagnosis of nephritic syndrome. Oliguira is not a common component of acute nephritic syndrome nowadays, and if azotemia develops, it is usually mild and transient. Classical causes of acute nephritic syndrome are acute diffuse proliferative (poststreptococcal) glomerulonephritis and rapidly progressive glomerulonephritis. Besides, the syndrome can manifest membrano-proliferative glomerulonephritis, and focal and diffuse proliferative lupus nephritis (1, 2).

What is much more commonly seen in the patients with glomerulonephritis that is hematuria. Glomerular hematuria is usually classified into four categories (3, 4, 5):

1) Gross hematuria. Brown-smoke urine with dysmorphic RBCs and RBC casts is usually accompanied by non-significant proteinuria, but not by any clinical sign or symptom of glomerulonephritis. As a rule, gross hematuria is seen in patients with IgA nephropathy and Alport syndrome.

2) Asymptomatic microscopic hematuria without proteinemia is often related to with strenuous physical exercises, fever, trauma, but not to glomerular injury. The diagnosis of this condition is made when more than two RBCs are found per one high power field in spun urine sediment. If the glomerulus is involved, biopsy will detect thin basement membrane disease, or mild forms of Alport syndrome and IgA nephropathy.

3) Asymptomatic microscopic hematuria with proteinuria is a rare condition, but is associated with a higher risk for a significant glomerular pathology. Among common causes of this type of hematuria there are more severe variants of thin basement membrane disease, Alport syndrome and IgA nephropathy. In addition, this laboratory sign can be seen in patients with membrano-proliferative glomerulonephritis, acute diffuse proliferative glomerulonephritis, and mesangial proliferative and focal proliferative lupus nephritis.

4) Symptomatic microscopic hematuria; this term is used when the patient presents with detectable clinical signs and symptoms:
   a. Systemic: fever, fatigue, malaise, perspiration, loss of weight and appetite, etc
   b. Extrarenal: cough and hemoptysis, GI bleeding, purpuric skin rash, etc
   c. Renal: edema, hypertension, oliguria, uremic manifestation, etc. When hematuria presents along with
       edema or hypertension, or oliguria, the term “acute nephritic syndrome” will be more relevant.

References
1. http://emedicine.medscape.com/article/240337-overview
2. http://www.uptodateonline.com/online/content/topic.do?topicKey=glom_dis/11292&selectedTitle=1%7E150&source=search_result
3. http://www.uptodateonline.com/online/content/topic.do?topicKey=renldis/7627&selectedTitle=1%7E150&source=search_result
4. http://www.uptodateonline.com/online/content/topic.do?topicKey=pedineph/18271&selectedTitle=3%7E150&source=search_resul
5. http://www.uptodateonline.com/online/content/topic.do?topicKey=pedineph/12709&selectedTitle=2%7E150&source=search_result