Vascular syndromes of the kidney Flashcards
What are some common vascular syndromes that lead to kidney dysfunction?
- pre-renal azotemia
- renal artery stenosis
- HTN nephrosclerosis
- renal vasculitis
What causes pre-renal azotemia?
In this setting, the renal parenchyma is normal and the urinary drainage system is normal.
The abnormality consists of decreased renal blood flow and/or decreased renal perfusion pressure.
What happens when the kidneys are under perfused?
In the presence of decreased renal blood flow or perfusion pressure, renal autoregulation occurs such that GFR is well maintained despite moderate changes in renal blood flow or arterial pressure.
In severely decreased flow or perfusion, however the renal autoregulatory response is overwhelmed and GFR becomes decreased as the body works to increase ECV
Medications which interfere with renal autoregulation will precipitate acute renal failure with less severely decreased renal blood flow and perfusion pressure. Name some
ACEIS, ARBs, and NSAIDs
How does preener azotemia present upon urinalysis?
Urinary findings: the urinalysis is normal, as the kidney is inherently normal.
Urinary specific gravity is increased and urine osmolality is increased.
Fractional excretion of sodium is
What casts are frequently seen in the concentrated urine (as in pre-renal azotemia)?.
Hyaline
Why does the Bun:creatinine ratio rise in pre-renal disease?
(typically > 20 to 1).
Serum creatinine is a function of GFR. BUN is a function of GFR and urinary flow rate.
Situations associated with decreased urinary flow rate lead to increased renal tubular urea reabsorption, leading to disproportionate increases in BUN, relative to creatinine.
Long-term uncontrolled hypertension leads to what in the kidneys?
arteriolar nephrosclerosis in the microcirculation of the kidney.
These progressive changes can lead to ischemic atrophy of glomeruli, and therefore decreased GFR
In this country, it is felt that this disease process is the second leading cause of end-stage renal disease, particularly in African-American populations
There is strong association between hypertensive nephrosclerosis and being homozygote for ____.
ApoL1 (this genetic variant is present with African ancestry and is rare in other racial groups.
What are the urinary manifestations of hypertensive nephrosclerosis?
non-nephrotic ranged proteinuria, typically less than 1 gram daily.
No evidence for inflammatory reaction (no hematuria or pyuria).
What does renal imaging studies show with hypertensive nephrosclerosis?
bilaterally symmetrically decreased sized kidneys with increased echogenicity.
What are renal vasculitis?
diseases associated with vasculitis typically present as nephritic process. More severe involvement can lead to rapidly progressive glomerulonephritis.
What are some Clinical examples of renal vasculitis?
ANCA associated RPGN, polyarteritis nodosa.
What happens in hemolytic uremic syndromes?
The primary pathologic defect is marked glomerular endothelial cell swelling and damage with platelet thrombi formation within the lumens of glomerular capillaries.
This typically leads to acutely decreased GFR.
Urinary findings will typically be nephritic. These syndromes are typically associated with thrombocytopenia and microangiopathic hemolytic anemia
