CH.5 Flashcards
what do renal function test evaluate (3)
glomerular filtration
conc
renal blood flow
what conc is being tested in renal function test
tubular reabsorption
tubular secretion
factors of urine volume and solute composition
diet
physical activity
health
what specific waste is looked at to assess kidney function
creatinine
urea
urine composition
5-6% dissolved solutes
94-95% water
what problem does uric acid cause in the kidneys
kidney stones
what is it called when more than 3 L of urine a produced per day
polyuria
what causes polyuria
- ADH secretion inadequate or receptors are ineffective
- solute increase
what is it called when less than 400 mL of urine are produced per day
oliguria
what causes oliguria (3)
urinary obstruction, tubular dysfunction, fluid loss
what is it called when no urine is produced
anuria
what cause anuria
progressive renal disease or renal failure
osmoses per kilogram
osmolality
what does osmolality measure
solute number not size or weight
where is finial osmolality determined
distal and collecting tubules when ADH is present
what is normal urine osmolality
1 to 3 times of plasma
def? comparison of density of urine to that of water
specific gravity.
what does specific gravity measure
number of particles and mass
what measures a more accurate selection of kidney’s conc ability
osmolality
what are the 3 most prevalent solutes in urine
urea
chloride
sodium
what will become unchanging in some chronic renal diseases
specific gravity or osmolality
what is urine conc the same as
plasma ultrafiltrate
what test is used to differentiate causes of polyuria
fluid deprivation test
what disease is ADH decreases
neurogenic diabetes insipidus
what disease has a lack of renal response to ADH
nephrogenic diabetes insipidus
how long is urine collected for a fluid deprivation test
12 hours
def? high specific gravity
heyperthenuria
def? fixed specific gravity
isothenuria
when would you see a person with a specific gravity greater than 1.035
injected with radiographic contrast media
what test measures rate at which the kidneys can remove a filterable substance from the blood
clearance test
what needs to be special about the substance analyzed in a clearance test
cannot be reabsorbed or secreted by the tubules
what is the most common clearance test
creatinine clearance
what substance does a exogenous clearance test require
inulin
what substance does a endogenous clearance test require
substance already present in the body
renal clearance formula
renal clearance (mL/min)= Urine conc (mg/dL) * Volume of urine (mL/min)/ plasma conc of substance (mg/dL)
what is the waste product of creatine
creatinine
how long does urine need to be collected for a creatinine clearance test
24 hrs
what other test needs to be done with a creatinine clearance test and when?
serum creatinine drawn during urine collection period
creatinine clearance formula
renal clearance (mL/min)= (urine creatinine * urine vol/ serum creatinin) * (1.73 m^2/ body surface area)
normal creatinine value
based on size of the person; larger person = more creatinine production
what happens to creatinine values in older people
decreases
normal reference range of plasma creatinine
0.5 to 1.5 mg/dL
is it difficult to preform a plasma and urine creatinine test
no
what is tested to detect chronic kidney disease
GFR
what is GFR based on
serum creatinine level, pt age, gender, and ethnicity
def? a low molecular weight protein found on surface of nucleated cells and shed into plasma
beta2-microglobulin
what molecule is readily passes through glomeruli and is 99.9% reabsorbed by proximal tubule
beta2-microglobulin
what is the marker of reduced tubular function
beta2-microglobulin
what is beta2-microglobulin used clinically for
ID early kidney transplant rejection
differentiate tubular and glomerular diseases
def? low molecular weight protein that has potential as a marker for long term monitoring of renal function
cystatin C
what molecule is produce by nucleated cells and filtered by glomerulus and is catabolized by tubular cells
cystatin C
increased plasma levels reflect
decreased glomerular funtion
is cystatin C routinely used
no
what molecule appears early diabetic nephrophathy
albuminuria
what does the presence of albumin mean
increased glomerular permeability
what is the most important factor associated with glomerular proteinuria
hyperglycemia
what is tested for renal blood flow
p-aminohippuric acid (PAH)
where is PAH secreted
proximal convoluted tubule
what is loosely bound to plasma proteins
PAH
when is PAH removed from the blood
when it comes in contact with functional renal tissue
what kind of procedure is PAH testing
exogenous
what does titratable acidity/urine ammonia test for
tubular secretion of H and NH4+
when is urine an “alkaline tide”
first morning
postprandial
lowest pH at night
def? renal tubular acidosis is inability to produce an acid urine
metabolic acidosis
def? secretion of H+
PCT
def? secretion of NH3
DCT
