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Flashcards in Glomerular Diseases Deck (49)
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What is the composition of endothelial cells of the glomerulus? How does this contribute to a selective barrier?

- fenestrated large pores 50-100nm wide which is pretty big considering albumin is 3.6 nm wide

- covered though in a negatively charged glycocalyx which provides a some charge barrier to other negatively charged proteins


What is the composition of the glomerular basement membrane? How does this contribute to the selective barrier?

Network of type 4 collagen and heparan sulphate proteoglycans, the latter of which are negatively charged and contribute the MAJOR charge selectively


What is the slit diaphragm?

A series of proteins that span the filtration slits (between the podocyte processes) by connecting to the actin cytoskeleton of the podocyte?


What is the major function of the slit diaphragm?

provides the major size restriction of protein filtration


Differentiate (briefly) between nephrotic and nephritic syndromes in terms of where the damage occurs and what urine findings you have?

1. Nephrotic syndrome: functional damage to the filtration barrier
- high protein in the urine
- may induce sodium retention and secondary edema and HTN

2. Nephritic syndrome: severe breaks in the glomerular capillary wall
- occur often in the context of significant inflammation in the glomerulus
- RBC, dysphormic RBC, and RBC casts all present
- protein present


broadly, glomerulonephritis refers to ...

autoimmune mediated disorders of the kidney


What is the relationship between GN and ESRD?

there is a high risk of progression from GN to ESRD
- depends on disease type.
- some can be rapid while others take years


What treatment type is used for GN?

immunosuppressive medications


What are the 4 clinical classifications of nephrotic syndrome?

1. proteinuria >3.5 g/d
2. hypoalbuminemia
3. hypercholestolemia
4. peripheral edema


Is GFR abnormal in nephrotic syndrome?

Often normal early on in the disease progression and only decreases later when scarring develops


What are 7 possible complications of nephrotic syndrome?

1. hypoalbuminemia
2. peripheral edema
3. hypercholesterolemia
4. hypergoalgulability and VTE
5. Infection
6. AKI
7. Lipiduria


What is the underlying pathophysiology of the peripheral edema seen in nephrotic syndrome?

- low albumin causing low oncotic pressure
- presence of protein in the urine induces tubular resorption of sodium


What is the underlying pathophysiology of the hypercholesterolemia seen in nephrotic syndrome?

low oncotic pressure induces hepatic production


What is the underlying pathophysiology of the
hypercoaguability seen in nephrotic syndrome?

- urinary losses of anticoagulant proteins
- increased production of procoagulant proteins


What is the underlying pathophysiology of the infection seen in nephrotic syndrome?

hypogammaglobulinemia from the losses of IGs in the urine


What is the underlying pathophysiology of the AKI seen in nephrotic syndrome?

- tubular injury from heavy proteins
- fluid shifts causing intravascular volume depletion
- interstitial edema in the kidney
- bilateral renal vein thrombosis


What is the underlying pathophysiology of the lipiduria seen in nephrotic syndrome?

- high amount of filtered lipid in urine reabsorbed by the tubular cells
- lipid droplets in urine
- oval fat bodies : sloughed tubular cells filled with lipid
- fatty casts: casts containing lipid filled tubular cells or free lipid droplets


What are the 3 most common causes of idiopathic nephrotic syndrome?

1. minimal change disease (MCD)
2. Focal segmental glomerulosclerosis (FSGS)
3. Membranous nephropathy (MN)


What are 3 possible systemic causes of nephrotic syndrome ?

1. Diabetes nephropathy
- most common cause of nephrotic syndrome
2. Lupus
3. Amyloidosis


How does minimal change disease present?

- sudden onset peripheral edema over several weeks
- younger children and older adults


What is the first line treatment option for MCD

- if they respond well (75% do) it carries a good future prognosis
- steroid resistance or relapses has a worse prognosis


What is the underlying histological change in MCD?

diffuse effacement of the foot process of podocytes leading to disruptions in the slit diaphragm


Describe the histological findings of focal segmental glomerulosclerosis (FSGS)

scarring in <50% of the glomeruli and only involving part of the glomeruli

also has diffuse foot process effacement like MCD


What is the clinical presentation of FSGS

More common presentation in adults
- 35% of nephrotic syndromes
- more common in black patients
- worse prognosis than MCD, more likely to progress to ESRD


What is the most common cause of nephrotic syndrome in caucasians?

Membranous nephropathy


What % of patients with membranous nephropathy present with high grade proteinuria?



What is the etiology of primary MN?

organ specific autoimmune disease with Ab againse the phospholiapse A2 receptor
- in 70% of cases


What are the histological findings of MN?

thickened capillary wall due to immune complex deposits under the podocytes and expansion of the GBM


What is the general workup of a patient with nephrotic syndrome?

1. Quantify severity
- creatinine and eGFR
- albumin, cholesterol
- 24hr urine for protein, ACR or PCR
- urinalysis and microscopy
2. R/O secondary causes
- autoimmune disorders -
- infection
- hematological malignancy
- diabetes


What is the etiology of nephritic syndrome?

Influx of inflammatory cells into the capillaries and/or mesangium of the glomerulus causing various problems:
- hypercellularity
- filtration barrier damage
- full breaks in the filtration barrier
- reduced kidney funciton early in disease
- salt retention and HTN with more moderate edema