B5.042 Prework 1: Pathophysiology of Renal Disease and Kidney Failure Flashcards
acute vs chronic kidney insufficiency
acute - developed in less than 3 months
chronic- ongoing for more than 3 months
3 classes of diseases that lead to kidney insufficiency
prerenal
intrarenal
postrenal
prerenal disease
reduced blood flow to kidney
usually due to stenosis
intrarenal disease classes
glomerular- glomerulonephritis
tubular- tubular necrosis
vascular- vasculitis
postrenal disease
obstruction of the urinary tract
what are some results of longstanding stenosis
ischemic kidney, reduced in size glomerular capillary tuft atrophy thickening of Bowman's capsule tubular sclerosis interstitial fibrosis inflammation
what can lead to acute tubular injury?
ischemia
toxins (drugs, radiocontrast dyes, gentamicin, heavy metals)
what is the course of progression of acute tubular necrosis (ATN)
initial phase with oliguria (<4 L urine production)
recovery phase with increase in urine but loss of electrolytes
what is the result of inflammatory tubular injury?
tubulointerstitial nephritis or pyelonephritis
can be acute or chronic
leads to inability to concentrate urine, polyuria, salt wasting, and metabolic acidosis
what is glomerulonephritis
glomerulus and components of the filtrating pathways can be altered
criteria for nephrotic syndrome
heavy proteinuria (>3.5 g/day)
hypoalbuminemia
hyperlipidemia and hypercholesterolemia
why do you get edema in nephrotic syndrome
decreased oncotic pressure due to hypoalbuminemia
why do you get hyperlipidemia and hypercholesterolemia in nephrotic syndrome
increased lipoprotein production in liver due to decreased albumin
criteria for nephritic syndrome
glomerular inflammation and bleeding/hematuria
oliguria and azotemia
variable salt retention and edema
red blood cell cast and dysmorphic red blood cells in urine
proteinuria below nephrotic range (<3.5 g/day)
what abnormalities occur when kidneys aren’t functioning properly
volume overload hypertension acidosis anemia bone disease
features of volume overload
decreased GFR high serum creatinine, azotemia, uremia oliguria electrolyte imbalances -less K+ secretion (hyperkalemia) -hyperphosphatemia (risk for vascular calcification) most important : sodium retention
results of volume overload
peripheral edema
pulmonary edema
hypertension
features of hypertension
increased intravascular volume sodium retention (primary problem) alteration of kidney regulatory mechanisms controlling ECF volume and osmolarity renin-angiotensin-aldosterone is activated and worsens disease
features of acidosis
low acid excretion
decreased release of acids derived from metabolism
results of acidosis
acid accumulation leads to body bicarb consumption
features of anemia
normocytic, normochromic
kidneys cant make EPO, altered oxygen sensing mechanism in kidney
results of anemia
decreased delivery of oxygen to tissues increased cardiac output ventricular hypertrophy congestive heart failure decreased cognitive functioning growth retardation in kids
what is erythropoietin?
released by proximal tubule epithelial cells and cortical interstitial cells
acts on bone marrow to produce new RBCs
features of bone disease
evident early in CKD
bone pain, increased risk of fracture, myopathy
osteomalacia, rickets
pathophys of bone disease in kidney dysfunction
GFR declines as a result of underlying renal disease
due to decreased GFR, less inorganic phosphate excretion
decreased serum calcium and calcitriol stimulate PTH production
phosphate retention also stimulates PTH secretion
what substance is used to estimate GFR
creatinine
fractional excretion
(Us/Ps)/(Ucr/Pcr)
normal fractional excretion of sodium
1-3%
what happens to fractional excretion in tubular dysfunction
increases
not enough is reabsorbed
normal BUN/Cr
15-20
findings in prerenal failure
decreased GFR, azotemia, oliguria
increased BUN/Cr
normal FEna (1-3%)
normal urine osmolarity
findings in intrarenal failure (tubular necrosis)
azotemia, oliguria with brown urine casts
decreased BUN/Cr (<15)
FEna > 3%, inability to concentrate urine (<500 mOsm/kg)
findings in postrenal failure
decreased GFR, azotemia, oliguria
decreased BUN/Cr
FEna > 3%
inability to concentrate urine (<500 mOsm//kg)
treatment of patients with renal insufficiency
control hypertension
control electrolytes
control body pH
control anemia
