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|QuestionAuthor={{Rim}}
|QuestionAuthor= {{YD}} (Reviewed by  {{YD}})
|ExamType=USMLE Step 1
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|MainCategory=Pathology
|MainCategory=Pathology
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|Prompt=A 7 year old male patient is brought by his mother to his pediatrician for red-colored urine. The patient does not have any chronic condition and does not take any medication. Upon further questioning, the mother explains that her son has recovered from a streptococcal pharyngitis two weeks prior to presentation. Physical examination is completely unremarkable. Work-up for the patient’s urinary condition includes serum activity of complements C3 and C5, and properdin (Factor P). Blood is immediately withdrawn.  Which of the following set of activities is most likely to be present in this patient for C3, C5, and Properdin (in order)?
|Prompt=A 7-year-old boy is brought by his mother to his pediatrician for red-colored urine and oliguria. The patient does not have any chronic condition and does not take any medication. Upon further questioning, the mother explains that her son has recovered from a streptococcal pharyngitis 10 days prior to presentation. Physical examination is remarkable for periorbital and peripheral edema. The patient undergoes further work-up, and serum activities of complements C3 and C5 and properdin (Factor P) are measured. Which of the following set of activities of C3, C5, and properdin is most likely associated with this patient's condition?<br>
 
[[Image:APSGN Complement WBR.png|600px]]
[[Image:
|Explanation=[[Acute post-streptococcal glomerulonephritis]] (APSGN) is the most common cause of nephritic syndrome (hematuria, hypertension, azotemia, oliguria, and edema) in the pediatric population. It is characterized by glomerular enlargement and proliferation of cellular components on light microscopy and a starry sky granular appearance (lumpy-bumpy) with antibody and complement deposition along the mesangium and the glomerular basement membrane on immunofluorescence. It occurs secondary to immunologic reaction that occurs 1 to 2 weeks following a nephritogenic group A streptococcal infection (pharyngitis or impetigo). The majority of cases of APSGN are self-limited, and complete resolution often occurs 1 to 2 months following initiation of symptoms. APSGN is characterized by [[hypocomplementemia]] with reduced serum C3, C5, and properdin (Factor P) due to alternative pathway activation. Properdin, a gamma globulin protein, is a positive regulator that stabilizes convertase, whose activity is required for the activation of the alternative pathway. Normalization of complement concentration, and increase in concentrations in some cases, can be delayed and occur 2-12 weeks following the onset of symptoms.  
|Explanation=Acute post-streptococcal glomerulonephritis (APSGN) is a type of acute nephritic syndrome associated with glomerular enlargement and proliferation of cellular components. It occurs secondary to immunologic reaction following nephritogenic group A streptococcal infection, usually pharyngitis or impetigo.
|AnswerA=A
 
|AnswerAExp=Following activation of the alternative complement pathway, serum concentrations of complements is reduced, not elevated.
APSGN is characterized by hypocomplementemia with reduced serum C3, C5, and properdin (Factor P) due to alternative pathway activation. Properdin, a gamma globulin protein, is a positive regulator that stabilizes convertase, whose activity is required for the activation of the alternative pathway. To note, normalization of complement concentration, and increase in concentrations in some cases, can occur anytime within 2-12 weeks of onset.
|AnswerB=B
 
Educational Objective:
Acute post-streptococcal glomerulonephritis is a type of acute nephritic syndrome that occurs secondary to a group A streptococcal pharyngitis or impetigo.  Serum concentrations of alternative pathway complements C3 and C5, and properdin will be reduced in APSGN.
 
Reference:
Wyatt RJ, Forristal J, Clark DW, Sugimoto S, et al.  Complement profiles in acute post-streptococcal glomerulonephritis.  Pediat Nephrol.  1988;2:219-223.
 
|AnswerA=Increased - Increased - Increased
|AnswerAExp=Following activation of alternative complement pathway, serum concentrations of complements is reduced, not elevated.
|AnswerB=Increased - Decreased - Decreased
|AnswerBExp=C3 is generally reduced to a greater extent than C5 in the case of APSGN.
|AnswerBExp=C3 is generally reduced to a greater extent than C5 in the case of APSGN.
|AnswerC=Decreased - Increased - Increased
|AnswerC=C
|AnswerCExp=C5 and Properdin would not be elevated in APSGN.
|AnswerCExp=C5 and properdin would not be elevated in APSGN.
|AnswerD=Decreased - Decreased - Decreased
|AnswerD=D
|AnswerDExp=Serum concentrations of alternative pathway complements C3 and C5, and properdin will be reduced in APSGN.
|AnswerDExp=Serum concentrations of the alternative pathway complements C3 and C5 and properdin will be reduced in APSGN.
|AnswerE=Decreased - Decreased - Increased
|AnswerE=E
|AnswerEExp=Properdin is a component of the alternative pathway. Similar to C3 and C5, its serum concentration also decreases in APSGN.
|AnswerEExp=Properdin is a component of the alternative pathway. Similar to C3 and C5, its serum concentration also decreases in APSGN.
|Approved=No
|EducationalObjectives=Acute post-streptococcal glomerulonephritis (APSGN) is a type of acute nephritic syndrome that occurs secondary to a group A streptococcal pharyngitis or impetigo. Serum concentrations of alternative pathway complements C3 and C5 and properdin will be reduced in APSGN.
|References=Wyatt RJ, Forristal J, Clark DW, Sugimoto S, et al. Complement profiles in acute post-streptococcal glomerulonephritis. Pediat Nephrol. 1988;2:219-223.<br>
First Aid 2014 page 538
|RightAnswer=D
|Approved=Yes
}}
}}

Latest revision as of 00:25, 28 October 2020

 
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathology
Sub Category SubCategory::Renal
Prompt [[Prompt::A 7-year-old boy is brought by his mother to his pediatrician for red-colored urine and oliguria. The patient does not have any chronic condition and does not take any medication. Upon further questioning, the mother explains that her son has recovered from a streptococcal pharyngitis 10 days prior to presentation. Physical examination is remarkable for periorbital and peripheral edema. The patient undergoes further work-up, and serum activities of complements C3 and C5 and properdin (Factor P) are measured. Which of the following set of activities of C3, C5, and properdin is most likely associated with this patient's condition?

]]

Answer A AnswerA::A
Answer A Explanation AnswerAExp::Following activation of the alternative complement pathway, serum concentrations of complements is reduced, not elevated.
Answer B AnswerB::B
Answer B Explanation AnswerBExp::C3 is generally reduced to a greater extent than C5 in the case of APSGN.
Answer C AnswerC::C
Answer C Explanation AnswerCExp::C5 and properdin would not be elevated in APSGN.
Answer D AnswerD::D
Answer D Explanation AnswerDExp::Serum concentrations of the alternative pathway complements C3 and C5 and properdin will be reduced in APSGN.
Answer E AnswerE::E
Answer E Explanation AnswerEExp::Properdin is a component of the alternative pathway. Similar to C3 and C5, its serum concentration also decreases in APSGN.
Right Answer RightAnswer::D
Explanation [[Explanation::Acute post-streptococcal glomerulonephritis (APSGN) is the most common cause of nephritic syndrome (hematuria, hypertension, azotemia, oliguria, and edema) in the pediatric population. It is characterized by glomerular enlargement and proliferation of cellular components on light microscopy and a starry sky granular appearance (lumpy-bumpy) with antibody and complement deposition along the mesangium and the glomerular basement membrane on immunofluorescence. It occurs secondary to immunologic reaction that occurs 1 to 2 weeks following a nephritogenic group A streptococcal infection (pharyngitis or impetigo). The majority of cases of APSGN are self-limited, and complete resolution often occurs 1 to 2 months following initiation of symptoms. APSGN is characterized by hypocomplementemia with reduced serum C3, C5, and properdin (Factor P) due to alternative pathway activation. Properdin, a gamma globulin protein, is a positive regulator that stabilizes convertase, whose activity is required for the activation of the alternative pathway. Normalization of complement concentration, and increase in concentrations in some cases, can be delayed and occur 2-12 weeks following the onset of symptoms.

Educational Objective: Acute post-streptococcal glomerulonephritis (APSGN) is a type of acute nephritic syndrome that occurs secondary to a group A streptococcal pharyngitis or impetigo. Serum concentrations of alternative pathway complements C3 and C5 and properdin will be reduced in APSGN.
References: Wyatt RJ, Forristal J, Clark DW, Sugimoto S, et al. Complement profiles in acute post-streptococcal glomerulonephritis. Pediat Nephrol. 1988;2:219-223.
First Aid 2014 page 538]]

Approved Approved::Yes
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