What is the cause of this nephropathy?

[Chessmatic]

A 34-year-old woman presents to her primary care physician complaining of puffiness in her legs, arms, and face for 3 days. She often feels a little “bloated” during her menstrual period but is currently in the middle of her cycle, and states that she has not been drinking more than usual or eating too much salt. Examination reveals generalized edema but is otherwise unremarkable. Her physician draws blood for complete blood cell count, electrolytes, and thyroid function tests, and does a dipstick urinalysis in his office which shows 2+ proteinuria. He decides to hospitalize her and perform a renal biopsy to determine the etiology of her nephrotic syndrome. Biopsy shows a thickened basement membrane and immunofluorescence reveals IgG and C3 deposits in a “spike and dome” pattern in the basement membrane. Which of the following is the most likely cause of this patient’s nephropathy?
(A) Anti–glomerular basement membrane antibodies
(B) Hepatitis B virus
(C) Idiopathic
(D) Penicillamine
(E) Systemic lupus erythematosus

[USMLE-Story]

Am thinking SLE

[Chessmatic]

The correct answer is A. This patient has Goodpasture’s syndrome characterized by deposition of antibodies to the basement membrane in glomeruli and alveoli. This leads to glomerulonephritis with symptoms of renal failure, hematuria, and nephritic range proteinuria, as well as pulmonary hemorrhage causing cough and occasionally hemoptysis and bloody effusions at the lung bases. Immunofluorescence staining of a renal biopsy sample would show the pathognomonic linear deposition of the antiglomerular basement membrane antibody.

Answer B is incorrect. Cryoglobulinemia, often associated with hepatitis B or C infection, causes glomerular disease associated with necrotizing skin lesions, arthralgias, fevers, and hepatosplenomegaly.

Answer C is incorrect. IgA deposition in the glomerular mesangium is seen in IgA nephropathy, or Berger’s disease. It presents with gross hematuria and nephrotic syndrome but does not cause pulmonary symptoms.

Answer D is incorrect. Postinfectious glomerulonephritis following group A streptococcal infection causes edema, oliguria, and hypertension, and does not cause concomitant pulmonary symptoms such as those seen in this
patient.

Answer E is incorrect. Inflammation of small vessels, or small vessel vasculitides, such as Wegener’s granulomatosis, Churg-Strauss disease, and microscopic polyangiitis, cause pauci-immune glomerulonephritis characterized by renal failure with lack of antibodies on immunofluorescence staining.

[timhabana]

Please, help clarifying this because it has me puzzled. The most common cause of adult nephrotic syndrome is the membranous glomerulonephritis. It is characterized by marked thickening of the basement membrane confering the "spikes and dome " appearance seen on Light microscopy. On EM: subepithelial electron-dense immune complexes are seen and the Immunofluorescence is granular with presence of IgG/C3. I do not see why the answer to the question is Goodpastures when this syndrome rarely causes nephrotic syndrome but nephritic.

[haga]

I don't think that's the right answer.

Goodpasture's causes a crescentic nephritis, not a spike and dome pattern. Additionally it causes nephritic not nephrotic, so you would see way more blood in the urine rather than protein.

Based on the stem, the best answer would be SLE. Spike and dome is membranous GN, and SLE is one of the main causes and would perfectly fit this patients description...ie. young woman with granular deposits.

[neoeinstein]

Yeah its explanation to the question have wrong choices and maybe referring to another question.

yeah its membranous nephropathy for sure. but which etiology? since it has no clues, i think idiopathic is the most common cause.

I remembered kaplan states that before you do renal biopsy on a suspected nephrotic syndrome, you should investigate other causes like HepB&C, drugs(NSAIDS,Penicallamine), HIV, SLE, Lymphoma,etc.

So the point that the pt undergone biopsy means that they can't find any secondary cause for the nephrotic syndrome so it is maybe idiopathic membranous nephropathy.

*or maybe the membranous nephropathy is due to NSAID use since the pt complains of "dysmenorrhea" and not hydrated well.