WBR0647

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology, MainCategory::Pathophysiology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 22 year old man presents emergency department in panic because he noticed bright red blood in his urine. Upon questioning the patient reports that he had a similar episode a few months ago but he did not give it much attention because it subsided alone. The patient explains that the first episode occurred while he was on sick leave for a viral bronchitis. Physical exam is unremarkable. Urinalysis shows >100 RBCs /HPF, with 1+ proteins noted on dipstick. Which of the following glomerular structures is the most likely to be involved in this patient? ]]
Answer A	AnswerA::A
Answer A Explanation	AnswerAExp::This refers to the glomerular capillary or endothelial cell. Endothelial involvement is not seen in IgA Nephropathy. It may be seen in lupus nephritis or membranoproliferative glomerulonephritis.
Answer B	AnswerB::B
Answer B Explanation	AnswerBExp::Mesangial involvement is characteristic of IgA nephropathy.
Answer C	AnswerC::C
Answer C Explanation	AnswerCExp::This refers to the podocyte. It is affected focal segmental glomerulosclerosis, not in IgA nephropathy (at least in early stages)
Answer D	AnswerD::D
Answer D Explanation	AnswerDExp::This refers to the glomerular basement membrane which is usually spared in IgA nephropathy. It is involved in the pathogenesis of Alport syndrome and membranoproliferative glomerulonephritis among others.
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::This refers to a podocyte foot process which is usually effaced in minimal change disease and is the cause of the proteinuria. Foot processes are not affected in IgA nephropathy.
Right Answer	RightAnswer::E
Explanation	[[Explanation:: Minimal change disease (MCD), also known as lipoid nephrosis, is the most common primary nephrotic syndrome in childhood accounting for >85% of all cases. It usually presents in young children often after an upper respiratory infection. Clinically, the hallmark of MCD like most nephrotic syndromes is edema and massive proteinuria > 3 g/24h (classically selective to albumin) with minimal to absent hematuria. MCD is a T-cell mediated glomerular disease whose cause is not well understood. On light microscopy, kidney biopsy is usually normal or shows very mild lipid accumulation in tubular cells (hence the name lipoid nephrosis). Definitive diagnosis usually requires electron microscopy of the biopsy specimen that would show retained podocytes but with effacement of the podocyte foot processes. The treatment of choice is corticosteroids with 90% of patients responding within 2 weeks of initiation. Learning objectives: Minimal change disease is the most common cause of nephrotic syndrome in childhood. It is caused by podocyte foot process effacement. References: Grimbert P, Audard V, Remy P, Lang P, Sahali D. Recent approaches to the pathogenesis of minimal-change nephrotic syndrome. Nephrol Dial Transplant. 2003;18(2):245-8. The primary nephrotic syndrome in children. Identification of patients with minimal change nephrotic syndrome from initial response to prednisone. A report of the International Study of Kidney Disease in Children. J Pediatr. 1981;98(4):561-4. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::IgA Nephropathy, WBRKeyword::hematuria, WBRKeyword::mesangial pattern, WBRKeyword::mesangium
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::