Renal Path Flashcards
What do the kidneys do?
- Excrete waste
- Regulate water and salt balance
- Regulate pH: acid/base
- Endocrine function
What endocrine function do the kidneys have?
- Renin
- Erythropoietin
- 1- alpha- hydroxylate production for Ca2+
How much do those little bitches way (kidneys)?
150 grams each
What are the 4 components of the kidney?
Glomeruli
Tubules
Interstitium
Blood vessels
What is synonymous with foot processes?
Podocytes
Visceral epithelium
What are the other layers of the capillaries in the glomerulerus?
- Fenestrated endothelial cells
- Glomerular basement membrane
What type of collagen monomers make up the GBM?
Type IV collagen
What separates foot processes?
Filtration slits
- 20-30 nm
What are the slit diaphragm proteins?
Nephrin and Podocin
What is characteristic of nephrotic syndrome?
- Protein defects in Nephrin and Podocin
- podocyte fusion
What is the origin of Mesangial Cells and Mesangial matrix?
Mesenchymal origin
What is the purpose of Mesangial cells?
- Contractile
- phagocytic
- proliferation
- Secrete inflammatory mediators
- lay down collagen
what is highly permeable in the glomerular?
Water and lower molecular weight proteins
What makes up the juxtaglomerular apparatus?
- Macula densa
- Juxtaglomerular cells
- extraglomerular mesangial cells
What is the purpose of the the juxtaglomerular cells?
Secrete renin
What is the purpose of the macula densa?
Detects Cl- delivery. Synonymous with Na+ delivery
Where are the peritubular capillaries located?
Interstitium
- contains fibroblast like cells
What are the categories of renal disease?
- Glomerular
- Tublointerstitial
- Vascular
What are the common causes of glomerular pathology?
Immune mediated
What is the common cause of tubulointerstitial pathology?
Toxic/ischemic and inflammatory reactions
What is uremia?
Azotemia and clinical sx’s
- like gastroenteritis, anemia, neuropathy, pruitis, pericarditis ect
What is the classic presentation of nephritic syndrome?
- Hematuria
- Mild to moderate proteinuria
- HTN
What is the classic presentation of nephrotic syndrome?
- > 3.5 gram/day proteinuria
- hypoalbuminemia
- edema
- hyperlipidemia
- lipiduria
What are the classic presentations of acute renal failure?
- Rapid decline of GFR
- Rapid onset Azotemina
- Oliguria or anuria
- Due to glomerular, tubulointerstitial or vascular
What is the classic presentation of chronic renal failure?
GFR persistently <60 ml/min/1.73m^2
- at least 3 months
- persistent albuminuria
What is the classic presentation of renal tubular defects?
- Polyuria
- Nocturia
- Electrolyte imbalances
- Inherited or acquired
What is the classic presentation of urinary tract infections?
Pyuria and bacteriuria
Pyelonephritis and cystitis
What is the classic presentation of nephrolithiasis?
Renal colic
Hematuria
What are the 4 stages of renal dz?
- Diminished renal reserve
- Renal insufficiency
- Renal failure
- End stage renal dz
What is the definition of diminished renal reserve?
GFR around 50% of normal
- Normal range of BUN/CR and asymptomatic
What is renal insufficiency?
GFR is 20-50% normal
- onset azotemia
- anemia
- HTN
What is renal failure?
GFR <20-25% normal
- edema
- metabolic acidosis
- uremia
What is end stage renal disease?
GFR <5% of normal
- terminal stage of uremia
What is the best overall measure of kidney function?
GFR
-Clearance= UV/P
Urine conc.*urine flow/Plasma conc.
What are some analytes to measure clearance?
Insulin Iothalamate EDTA Iohexol Creatinine
What can cause extrarenal elimination of Cr?
Bacteria
Is Cr perfect for GFR clearance?
no
- close but 10-20% is secreted by proximal tubule
- serum levels related to body muscle mass and diet
What is the estimated creatinine clearance formula?
140-ageweight/72serum cr (.85 females)
How does one calculate MDRD?
175 x (SCr)^-1.154 x (age)^ -0.203 x 0.742 if female, or 1.212 if black
Adjusted for body surface area. (ml/min/1.73m^2)
What are clearance measurements still used?
- Unsual body habitus- muscle wasting
- rapidly changing kidney function
- Kidney donors or research protocols
What is BUN?
Major end product of protein nitrogen metabolism
- normal is 10-20 mg/dL
What affects BUN? Prerenal and increase synthesis of urea?
Catabolism - burns fever and stress
- high protein diet
- GI bleed
- Hemolysis
- Maliganancy
What increases BUN? Prerenal but decrease renal perfusion?
HoTN/Shock
- CHF
- Dehydration
- Renal vein thrombosis
What is a caveat of BUN?
When renin is releases in hypovolemia, this increases aldosterone which causes increased resorption of Na/H2o.
- BUN passively follows. Thus increase in BUN which is out of proportion to any change in GFR
What are some postrenal increase in BUN?
Benign prostatic hypertrophy
- Prostatic carcinoma
- tumor of bladder or ureter
- retroperiotoneal mass
- urinary calculi
What are some factors that cause a decrease in BUN?
Decrease synthesis- low protein intake, liver dz
- hemodilution
What are factors that can cause hemodilution?
Pregnancy
- overhydration
- psychogenic polydipsia
- DI
What is the purpose of creatinine?
Energy storage reservoir for conversion to ATP
- usually constant daily excretion
- normal is 0.7-1.2 mg/dL
- slightly better estimate of GFR than BUN
- less affected by kidney perfusion
What are some pre-renal increases in creatinine causes?
Increase syn:
- muscle hypertrophy
- muscle necrosis
- anabolic steroid use
- high meat diet
- intense exercise
What are some pre-renal increase in Cr by decrease perfusion?
CHF
HoTN
Shock
What are some post-renal increases in Cr?
Urinary tract obstruction
What is a normal BUN:Cr ratio?
10-20 or 15:1
What is a common ratio of BUN:Cr in renal dz?
40:4 or 10:1
What is a common ratio of BUN:Cr in pre-renal dz?
80:2 or 40:1
What is the fraction of excreted Na+?
helps diff between renal dz and pre-renal.
- urine (NaplasmaCr100/Urine cr*plasma NA)
What favors pre-renal dz?
FeNA <1%
What favors ATN?
> 2.0% FeNa
What is normal protein in the urine over 24 hrs? Whats its make up?
150mg
- Albumin
- Small Globulins
- Tamm-Horsfall protein
What are some function things that cause decrease protein in urine?
Heavy exercise
cold exposure
Fever
what are some cause sof proteinuria without Renal dz?
CHF
Massive obesity
Constrictive pericarditis
Renal vein thrombosis
