Membranous nephropathy

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Membranous nephropathy

Renal system


Membranous nephropathy


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Membranous nephropathy

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A 52-year-old female comes to the primary care physician due to worsening weight gain. She has gained approximately 20 lbs over the past six weeks. In addition, the patient has been experiencing lower extremity edema and has noticed her urine appears more cloudy than usual. Past medical history is notable for hypertension and hyperlipidemia. Temperature is 37.3°C (99.1°F), pulse is 76/min, respirations are 18/min, blood pressure is 137/84 mmHg, and O2 saturation is 97% on room air. Physical exam is notable for bilateral pitting edema of the lower extremities. A urinalysis is notable for 4+ protein and oval fat bodies but no hematuria. A renal biopsy is performed, and the following is visualized on light microscopy:  

Reproduced from: Wikipedia  
Which of the following is most suggestive of this patient’s underlying diagnosis?  

External References

First Aid








Membranous nephropathy p. 618, 619, 723

membranous nephropathy, primary

autoantibody p. 113


Content Reviewers

Membranous glomerulonephritis, also known as membranous nephropathy, is where the glomerular basement membrane, or GBM, which lines the glomeruli in the kidney, becomes inflamed and damaged, which results in increased permeability and proteins being able to filter through into the urine, causing nephrotic syndrome.

But what exactly is nephrotic syndrome? Well usually the glomerulus only lets small molecules, like sodium and water, move from the blood into the kidney nephron, where it eventually makes its way into the urine. But with nephrotic syndromes, the glomeruli are damaged and they become more permeable, so they start letting plasma proteins come across from the blood to the nephron and then into the urine, which causes proteinuria, typically greater than 3.5 grams per day.

An important protein in the blood is albumin, and so when it starts leaving the blood, people get hypoalbuminemia—low albumin in the blood.

With less protein in the blood the oncotic pressure falls, which lowers the overall osmotic pressure, which drives water out of the blood vessels and into the tissues, called edema.

Finally, it’s thought that as a result of either losing albumin or losing some protein or proteins that inhibit the synthesis of lipids, or fat, you get increased levels of lipid in the blood, called hyperlipidemia.

Just like the proteins, these lipids can also get into the urine, causing hyperlipiduria.

And those are the hallmarks of nephrotic syndromeproteinuria, hypoalbuminemia, edema, hyperlipidemia, and lipiduria.

Alright, so with membranous glomerulonephritis, the basement membrane becomes damaged which causes nephrotic syndrome. How does this happen, though? Well, ultimately this damage is caused by immune complexes—complexes composed of an antigen with an antibody bound to it.


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  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Membranous nephropathy in children: clinical presentation and therapeutic approach" Pediatric Nephrology (2009)
  6. "Thrombospondin Type-1 Domain-Containing 7A in Idiopathic Membranous Nephropathy" New England Journal of Medicine (2014)
  7. "Immunosuppressive treatment for idiopathic membranous nephropathy in adults with nephrotic syndrome" Cochrane Database of Systematic Reviews (2014)
  8. "Membranous Glomerulopathy: Emphasis on Secondary Forms and Disease Variants" Advances in Anatomic Pathology (2001)

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