Shoeny Renal 1 Flashcards
What is the nephron composed of?
Glomerulus Proximal Tubule Loop of Henle Distal Tubule Collecting Duct
What is the function of the Nephron?
Filtration
Blood enters from the renal artery into the afferent arteriole and exits via the efferent arteriole
Substances up to what size can pass through the renal capillaries?
40 K Daltons
Larger substances such as proteins and RBCs, do not usually pass
When might substances larger than 40K daltons pass through the renal capillaries?
Renal damage
The proximal tubule reabsorbs large quantities of?
H20, along with glucose, uric acid, Na, Cl and HCO3
Loop of Henle, after the proximal tubule, reabsorbs what?
Further reabsorbs Na, Cl, and H20
The distal tubule controls what substances from going into the collecting duct?
Distal tubule controls excretion of Na, K, HC03, and H into the collecting duct
The collecting duct regulates the amount of water in the urine to the effect of what hormone?
ADH (anti diuretic hormone)
Substances enter the the nephron through _____. Substances are reabsorbed from the tubule back to circulation via the __________
Substances enter the nephron through peritubular blood (secretion) or from interstitital space.
Substances are reabsorbed from the tubule back to the circulation via the peritubular vasculature.
What are 3 renal function tests?
BUN
Creatinine
Urinalysis
BUN measures what?
Measures concentration of nitrogen (urea) in the serum.
This is a marker of protein metabolism.
When is BUN elevated?
Elevated in renal failure but other causes as well (CHF, acidosis)
Normal range 8-20mg/dl
What is Creatinine?
Catabolic product of creatine-phosphate-skeletal muscle contraction.
Metabolic product of muscle creatine, day to day variation is negligible in healthy kidneys. Rise in creatinine is due to kidney dysfunction or damage- Shows up as decrease in GFR.
Creatinine production depends on what?
Daily production depends on muscle mass
Creatinine is excreted entirely by?
the Kidneys, directly related to renal function
What are normal levels of Creatinine? Elevations suggest what?
Normal is 0.5-1.1 mg/dl
Elevations suggest chronicity of renal disease.
How does Creatinine correlate with renal function?
Creatinine increases are inversely related to renal function.
Doubling of creatinine = 50% decrease in renal function.
Who would have a higher creatinine level? Who would have a lower creatinine level?
Muscle mass matters. People with greater muscle mass generally have a higher creatinine level.
People with lower creatinine would be people with lower muscle mass - neurogenic complications - MS, post stroke, women (generally)
What is glomerular filtration rate? What is the gold standard to measure glomerular filtration rate?
Glomerular filtration rate is an assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging
Gold standard = Inulin filtration rate
Actuality = Creatinine clearance
What is creatinine clearance an approximation of? What are normal ranges?
Creatinine clearence is an approximation of GFR.
Normal ranges, Male = 107-140, Female = 90-107
What is Creatinine clearance used for?
Assessing kidney function in acute or chronic renal failure.
Monitoring effects of drug therapies.
Monitoring therapeutic drugs and determining dosage.
How do you test creatinine clearence?
Requires 24 hour urine collection
Serum creatinine drawn within 24 hours of urine collection
Creatinine clearence = (Ucr mg/dl x Urine volume ml/min)/(PCr mg/dl)
What is the Cockcroft-Gault Equation?
This estimates creatinine clearance without 24 hour urine studies.
This is useful for renal dosing of medications.
CrCl (ml/min) = (140-age) x wt/(cr x 72)
Multiply by 0.85 if women to correct for mm mass.
What is the MDRD equation? What does it incorportate into its equation?
Modification of Diet in Renal Disease
Incorporates age, sex, and ethnicity into equation.
GFR mls/min = 1.86 x PCr x Age
multiply by 0.742 if female, multiply by 1.210 if African American.
What does urinalysis consist of?
Consists of dipstick and microscopic analysis.
Color and clarity part of report.