Kidney Function Tests Flashcards
These are the tests to assess your kidney.
RENAL FUNCTION TESTS
are bean-shaped organs
Kidneys
Functional unit of your kidney are the ____.
Nephrons
2 regions of Nephrons
The outer region - cortex
Inner region - medulla
Nephrons have 2 types:
- in the medulla
- Loop of Henle may extend up to the cortex
Kidneys have several functions in the body:
- Elimination of waste products
- Maintenance of blood volume
- Maintenance of electrolyte balance
- Maintenance of Acid-Base Balance
- Endocrine Function (renin-erythropoietin
General assessments for kidney function
- GFR (Glomerular Filtration Rate)
- Tubular Function
- Renal Function
GFR tests
- Clearance Tests
- Cystatin C
- Beta Trace Protein
Tubular function tests
Excretion Tests
Concentration Test
Renal blood flow
- BUN
- Creatinine
- BUA
Usually the test is clearance test - It will determine
if your kidneys, particularly your glomerulus
are able to filter out.
Glomerular Filtration Rate (GFR)
Removal of the substance from plasma into
urine in a fixed time. It will represent the
volume of plasma that would contribute all the
solute excreted. what we use in this clearance test is 24 hr. urine.
Clearance Test
Sample used in GFR clearance test
24 hour urine
There are 3 types of clearance test:
Inulin Clearance
Creatinine Clearance
Urea Clearance
Reference method.It is not routinely done because of the necessity for continuous IV infusion.
Inulin Clearance
Each kidney contains approximately ___ nephrons.
’ 1 million
Each nephron is a complex apparatus composed of five basic parts
- The glomerulus
- The proximal convoluted tubule
- The long loop of Henle
- The distal convoluted tubule
- The collecting duct
—a capillary tuft surrounded by the expanded end of a renal tubule known as Bowman’s capsule
glomerulus
has an afferent arteriole that carries the blood in and an efferent arteriole carrying the blood out. The efferent arteriole branches into peritubular capillaries that supply the tubule.
Glomerulus
the distal and proximal convoluted tubule is located in the
Cortex
-composed of the thin descending limb, which spans the medulla, and the ascending limb, which is located in both the medulla and the cortex, composed of a region that is thin and then thick.
The long loop of Henle
formed by two or more distal convoluted tubules as they pass back down through the cortex and the medulla to collect the urine that drains from each nephron
collecting duct
Collecting ducts eventually merge and empty their contents into the ?
renal pelvis.
There are three basic renal processes:
Glomerular filtration
Tubular reabsorption
Tubular secretion
is filtered and secreted, but not reabsorbed;
NH3
is filtered and a portion reabsorbed:
Glucose
are filtered and completely reabsorbed (not shown).
Amino Acids
It would provide an estimate of the amount of plasma that flows through the kidney, glomerulus of the kidney particularly. It is commonly performed. It is an excellent measure of renal function
Creatinine Clearance
It can actually demonstrate progression of renal disease or response to therapy.
urea clearance
Is a low molecular weight protease inhibitor and
produced at a constant rate by all nucleated
cells.
Cystatin C
In Cystatin C, only ___ is in-charged.
glomerulus
It is a low molecular-weight lipoprotein, it actually belongs to lipocalin family. It is not commonly nerformed and also Cvstatin Cl
Beta Trace Protein
Para-Amino Hippurate Test It measures renal
plasma flow.
Excretion Test
The dye you can use for Excretion Test
Para-Amino Hippurate, Phenolsulfonphthalein Dye Test.
It reflects the function of the B. collecting tubules and the loops of Henle. It will assess the quantity of solutes present in urine, which reflects the ability the kidney to concentrated urine.
Concentration Test
Specimen used in concentration test
first morning urine
Concentration Test will check the ability of kidney to produce concentrated urine so you can use ___ or ____.
specific gravity (simplest) or osmolality (more
sensitive than the specific gravity)
Measures the production of NPNs - Nonprotein
Nitrogenous Compound.
RENAL BLOOD FLOW
Used to monitor the renal function, will increase in the bloodstream if there is a problem in the kidney.
Nonprotein Nitrogenous Compound
NPNs are actually eliminated, filtered
in the ___ and then and secreted in the ___.
filtered in the kidney and then and secreted in the urine.
are breakdown products of your protein and
breakdown of nucleic acids. amino acids.
Nonprotein Nitrogenous Compound.
a low-molecular-weight protein produced at a steady rate by most body tissues
Cystatin C
Cystatin C is freely filtered by the ___, reabsorbed, and catabolized by the ____.
freely filtered by the glomerulus, reabsorbed, and catabolized by the proximal tubule.
appear to be unaffected by diet, gender, race, age, and muscle mass.
Cystatin C
derived by mathematically relating the serum creatinine concentration to the urine creatinine concentration excreted during a period of time, usually 24 hours.
Creatinine clearance
assess glomerular filtration or tubular secretion.
inulin, or p-aminohippurate
was one of the first clearance tests performed; however, it is no longer widely used since it does not accurately provide a full clearance assessment.
Urea clearance
has become the standard laboratory method for determining the GFR
creatinine clearance
rate at which creatinine and urea are removed or cleared from the blood into the urine is termed
clearance
When you breakdown protein, it will become ____, your amino acid will become ______ and since ammonia is toxic to the body, it will be converted or breakdown by the liver into
___.
Protein → amino acid → ammonia → urea (liver)
Several NPNs we excrete in our urine.
Urea
Amino acid
Uric acid
Creatinine
Creatine
Ammonia
The most numerous NPN is the
Urea
Almost ___ of the total NPN is UREA.
45%
The fewest NPN
Ammonia
Major product of protein catabolism
BLOOD UREA NITROGEN (BUN)
Formed in the liver, First metabolite to increase in kidney disease
BLOOD UREA NITROGEN (BUN)
BLOOD UREA NITROGEN (BUN) Reference values:
8-23 mg/dL
If you exceed BUN reference values (8-23 mg/dL) the possible reasons are:
- chronic renal disease
- stress
- burn
- high protein diet - If Diet not because of a disease.
- dehydration.
BUN: Creatinine ratic
10:1 - 20:1
Lab considerations (reject samples)
Non hemolyzed serum/plasma
Non fasting sample
No citrate or fluoride
For the plasma, refrain from using ___ or ____ because these two can inhibit urease
fluoride, citrate
how to get urea
BUN x 2.14
The first method and it is also called the Chemical Method because you are using a chemical
Direct Method
Chemical used for direct method
Diacetyl Monoxime Method
Another name for Diacetyl Monoxime Method
Fearon’s reaction
your Diacetyl Monoxime is hydrolyzed and it
will breakdown into
diacetyl + hydroxylamine
The Diacetyl form will react with your urea and will now form _____ this would be the one measured
Yellow Diazine Derivative
DAM + H20 → diacetyl + hydroxylamine
Diacetyl + Urea → Yellow Diazine Derivative
Direct method
You are actually measuring the Urea Nitrogen. This time you have to multiply it by 2.14. It is also your Enzymatic Method.
Indirect Method
Can you use citrate or fluoride in DAM
Yes
The basic principle of your Enzymatic Method/Indirect Method - the Urea is hydrolyzed first to yield ____ and ____.
ammonia ions and bicarbonate ions.
If Enzymatic and Urease is included, can you use fluoride or citrate?
No
Principle: First, it hydrolyzed the Urea using the Urease enzyme and forms ammonia and bicarbonate ions. The formed ammonia ions will let
2-oxoglutarate to react and NADH with the presence
of other enzyme GLDH to form glutamate and water. Your NADH + H+ will be NAD+.
Coupled Ureasel Glutamate Dehyrogenase
(GLD) Method - UV Enzymatic Method
proposed reference method of determination because it is very sensitive. It is expensive.
Isotope Dilution Mass Spectrometry (IDMS)
specific and rapid method of determination
conductimetric method
enzymatic methods used on many automated Instruments; best as kinetic measurement
GLDH coupled enzymatic
enzymatic methods Used In automated systems, multilayer film reagents, and dry reagent strips
GLDH coupled enzymatic
Used in automated systems, multilayer film
reagents, and dry reagent strips
Indicator dye