Glomerulonephritis Question: Clinical Case Scenario Cause

Question

A 6-year old boy is diagnosed with acute glomerulonephritis that developed after a streptococcal throat infection. At this time, the following manifestations are noted: decrease in urine output, increasing lethargy, hyperventilation, and generalized edema. Trace amounts of protein are detected in his urine. Blood analysis reveals the following: pH = 7.35; HCO3 = 18 mEq/L; hematocrit = 29%; Na = 132 mEq/L; K = 5.6 mEq/L; blood urea nitrogen (BUN) = 62 mEq/dL; creatinine = 4.1 mg/dL; and albumin = 2 g/dL. 

What is the probable cause of this boy’s glomerular disease? 

This boy likely developed glomerulonephritis after having a streptococcal throat infection. This often happens when the body produces extra antibodies that settle into the glomeruli. This causes inflammation. Is this correct?

Which laboratory values are abnormal? What is the significance of each abnormal value? 

Is he progressing to uremia? How can you tell?  

Answer 1

Jennifer wrote a good, thoughtful reply. Just a few things to add:

1. the elevated BUN and creatinine indicate the patient is experiencing intra-renal acute kidney injury
2. the hyperventilation, low HCO3, and just barely normal blood pH show the client is doing Kussmaul’s respirations to compensate for metabolic acidosis

Answer 2

Sounds like this boy developed post-streptococcal glomerulonephritis caused by Group A Strep (GAS) after a likely strep throat (pharyngitis) or impetigo infection. This happens when antibodies bound to the GAS bacteria deposit into the glomerular basement membrane of the nephron and can be classified as part of a wider group of nephritic syndromes. As for the lab values, the BUN tells about waste products and the creatinine tells about renal function. Since his creatinine is high this tells us that his kidneys are not working properly (we use creatinine to estimate glomerular filtration rate and therefore estimate kidney function). Since his BUN is also high this further supports that his kidneys are not clearing out waste products like they normally should be. His low albumin levels explains why he has edema, when you lose protein in the urine (as in Nephritic syndromes) this decreases the plasma oncotic pressure in the vessels, drawing fluid into the interstitial surroundings and causing edema.