CH. 5 Flashcards
Which of the following solutes are present in the
largest molar amounts in urine?
urea
chloride
sodium
Renal excretion is not involved in the elimination of
normal by-products of fat metabolism.
The concentration of which substances provides the
best means of distinguishing urine from other body
fluids?
creatinine and urea
What is the definition of the osmolality of a solution?
The number of solute particles per kilogram of
solvent
The osmolality of a solution containing 1.0 mole of
urea is equal to that of a solution containing
0.5 mole of NaCl.
The maximum osmolality that urine can achieve is
determined by the
osmolality of the medullary interstitium.
Serum osmolality remains relatively constant,
whereas the urine osmolality ranges from
one to three times that of serum.
Another name for excessive thirst is
polydipsia.
Specific gravity measurements are not affected by
solute charge
Which of the following solutes, if added to pure
water, affects the specific gravity more than it affects
its osmolality?
Glucose
Occasionally the specific gravity of a urine specimen
exceeds that physiologically possible (i.e., >1.040).
Which of the following substances when found in
urine could account for such a high value?
mannitol
The excretion of large volumes of urine (>3 L/day)
is called
polyuria
The daily volume of urine excreted normally ranges
from
500 to 1800 mL/day.
When the body is dehydrated, the kidneys
excrete solutes in as small a volume of urine as
possible.
The excretion of less than 400 mL of urine per day
is called
oliguria
The ultrafiltrate in the urinary space of the glomerulus has a specific gravity of 1.010 and the same as
the blood plasma.
conditions that may produce nocturia
pregnancy
chronic renal disease
fluid intake at night
Which renal function is assessed using specific
gravity and osmolality measurements?
Concentrating ability
A fluid deprivation test is used to
assess renal concentrating ability.
A fluid deprivation test involves the measurement of
serum and urine
osmolality
The volume of plasma cleared per minute in
excess of that required for solute elimination is
called the
free-water clearance
A free-water clearance value of −1.2 would be
expected from a patient experiencing
dehydration
Which of the following is an endogenous substance
used to measure glomerular filtration rate?
creatinine
Renal clearance is defined as the volume of
plasma cleared of a substance in a time interval.
Creatinine is a good substance to use for a renal
clearance test because it
has a constant plasma concentration.
Which of the following groups would be expected to
have the greatest 24-hour excretion of creatinine?
men
Creatinine clearance results are “normalized” using
an individual’s body surface area to account for
variations in the individual’s
muscle mass
A 24-hour urine collection is preferred for determination of creatinine clearance because of diurnal variation in the
GFR
Which of the following situations results in an erroneous creatinine clearance measurement?
A 24-hour urine collection maintained at room
temperature throughout the collection
The glomerular filtration rate is controlled by
renal blood flow
For measurement of renal plasma flow,
p-aminohippurate is an ideal substance to use
because it
is secreted completely in its first pass through the
kidneys.
What percentage of the total cardiac output is
received by the kidneys?
25%
Measuring the quantity of hydrogen ion excreted as
titratable acids and ammonium salts in urine provides a measure of
tubular secretory function.
The oral ammonium chloride test evaluates the
ability of the tubules to secrete
ammonia and hydrogen
what are the factors that change urine volume and solute composition
diet
physical activity
health
what organ regulates body fluid composition
kidneys
what kind of excretion is primary elimination route of soluble metabolic waste
renal excretion
what waste can be used to asses kidney function
creatinine and urea
polyphagia
excessive eating
what condition do diabetes mellitius patients have
polyuria
what 2 urine volume conditions are related
polyuria and nocturia
what causes oliguria
schelrosis
condition where there is no urine
anuria
normal osmolality range
275-1000
what determines the finial osmolality
distal and collecting tubles with ADH is present
what does specific gravity depend on
density and mass
normal range of specific gravity
1.002 to 1.035
what measure of urine concentration is more accurate reflection of kidney’s conc ability
osmolality
what happens to specific gravity or osmolality over time with patients with chronic renal diseases
concentrating ability slowly diminishes until they are unchanging
neurogenic
ADH decreased
nephrogenic
lack of renal response to ADH
increased body hydration = ____ ADH= ____ urine volume
decreased
increased
decreased body hydration = ____ ADH= ___ urine volume
increased
decreased
GFR
amount of plasma filtered through the glomerous
waste product of muscles
creatinine
true or false; creatinine is produced at a constant rate
true
what kind of sample collection is creatinine and serum creatinine for a creatinine clearance test
timed
what is the problem with creatinine
a small amount of creatinine is secreted by tubules resulting in an increased urine conc of creatinine
normal range of plasma creatinine
0.5 to 1.5 mg/dL
average BSA for adults
1.73
nonogram
charts to calculate BSA
low molecular weight protein found on surface of nucleated cells and shed into plasma
beta2-microglobulin
what is an advantage of beta2-microglobulin
99.9% is reabsorbed by proximal tubules
what is the marker of reduced tubular function
beta2-microglobulin
an increase in cystatin C in blood, _____ GFR
decreases
low-molecular-weight protein that has potential as a marker for long-term monitoring of renal function
cystatin C
what filters cystatin C
glomerulus
normal amount of albuminuria
5 mg
what protein would you expect to see in patients with early diabetic nephropathy
albuminuria
normal range of microalbuminuria
40-50 mg
what is the most important change associated with glomerular proteinuria
hyperglycemia
exogenous nontoxic weak acid secreted almost exclusively by proximal tubules, used as indicator of renal tubular secretory function
p-aminohippurate clearance
true or false: titratable acids are not constant
false
assess tubular function for removing acids
measurement of titratable acid versus urinary ammonia
what test are patients given ammonium chloride and measure series of urine pH and plasma bicarbonate
oral ammonium chloride test
what test diagnoses renal tubular acidosis
oral ammonium chloride test
what test checks how much plasma is being filtered and is an assessment of GFR
creatinine clearance
what test sees how well kidneys are able to conc urine
urine osmolality
what test uses electrophoresis to evaluate glomerular permeability to plasma proteins in urine
urine protein
what test looks at renal function
plasma creatinine
what proteins are apart of the acute phase reactant
alpha I
alpha II
what kind of gamma peak would you expect from monoclonal
sharp
what kind of gamma peak would you expect from multiple clonal
shallow
