A 40-year-old man comes to the nephrology clinic for follow-up due to poststreptococcal glomerulonephritis. He initially had gross hematuria and edema associated with hypertension and required treatment with a diuretic. Two weeks prior to the onset of symptoms, the patient had acute pharyngitis that resolved without treatment. At the time of diagnosis, the serum C3 level was decreased, and the antistreptolysin O titer was elevated. Which of the following factors most likely indicates a poor long-term prognosis for this patient's condition?

Question

A 40-year-old man comes to the nephrology clinic for follow-up due to poststreptococcal glomerulonephritis.  He initially had gross hematuria and edema associated with hypertension and required treatment with a diuretic.  Two weeks prior to the onset of symptoms, the patient had acute pharyngitis that resolved without treatment.  At the time of diagnosis, the serum C3 level was decreased, and the antistreptolysin O titer was elevated.  Which of the following factors most likely indicates a poor long-term prognosis for this patient's condition?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c09c_1ec4_8f63_833f6745f343_MD0005_00 Poststreptococcal glomerulonephritis (PSGN) is a nonsuppurative complication of a pharyngeal or skin infection (eg, impetigo). Infection with nephritogenic strains of group A Streptococcus (GAS) (eg, S pyogenes) results in the formation of antigen-antibody complexes, which are deposited on the glomerular basement membrane. Subsequent activation of complement and inflammation results in the development of nephritic syndrome 2-4 weeks after initial infection. Common clinical features include gross hematuria, hypertension, and edema (periorbital or generalized). Urine studies show red blood cells and casts and mild proteinuria, whereas serum studies commonly demonstrate elevated creatinine, antistreptococcal antibodies (eg, antistreptolysin O), and low C3 (due to consumption). PSGN is most common in children age 5-12 and has an excellent prognosis in this group, with most patients achieving complete normalization of renal function. However, up to 40% of adults diagnosed with PSGN develop chronic kidney disease, persistent hypertension, or recurrent proteinuria, with 10% progressing to end-stage renal disease. Preexisting kidney disease, metabolic syndrome, and diabetes are also poor prognostic indicators. (Choices B, D and E) Gross hematuria and hypertension are common features of PSGN. Antistreptococcal antibodies are typically elevated in patients with recent GAS infection and can be used to help confirm the diagnosis. However, antistreptolysin O antibodies may be falsely low in patients who received antibiotic therapy or in those with a GAS skin infection. None of these findings significantly affects the prognosis, whereas the difference in prognosis between adults and children has been noted in multiple studies. (Choice C) Corticosteroid treatment is recommended for minimal change disease, which also is far more common in children and has a worse prognosis in adults; however, this condition causes nephrotic syndrome (eg, heavy proteinuria, edema, hyperlipidemia). Corticosteroids are not indicated in PSGN. Educational objective: Poststreptococcal glomerulonephritis, a complication of group A Streptococcus species, presents with nephritic syndrome (eg, renal failure, hypertension, hematuria, red blood cell casts) 2-4 weeks after infection. It is most common in children and has an excellent prognosis in this age group; however, adults and those with a history of chronic kidney disease, metabolic syndrome, or diabetes have a worse prognosis and may develop end-stage renal disease. References: Bacterial infection-related glomerulonephritis in adults. (http://www.ncbi.nlm.nih.gov/pubmed/23302723) Post-streptococcal glomerulonephritis. (http://www.ncbi.nlm.nih.gov/pubmed/26866231)

A 40-Year-Old Man Comes to the Nephrology Clinic for Follow-Up