Chapter 26: Renal Function Flashcards Preview

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Flashcards in Chapter 26: Renal Function Deck (24):

Types of tests for Renal Function

- Urinalysis

- Serum Creatine

- Blood urea nitrogen (BUN) levels

- Tests of GFR (Glomerular Filtration Rate)

- the best test for evaluating kidney structure


Urinalysis (Types)

- provides important info about kidney function (shows macroscopic and microscopic WBC bacteria)

- single sample: main technique for urinalysis

- 24 hour: helpful for evaluating substances that are excreted in varying concentrations throughout the day

- Culture and Sensitivity: determine presence of microorganisms and drugs to which microorganisms are most sensitive


Urinalysis (odor)

- normal: slight due to breakdown of urea to ammonia

- abnormal: strong ammonia smell (bacteria, stands for a period of time)

- Food may cause different odors


Urinalysis (color)

- normal: pale yellow to amber color due to urochrome pigments and slightly acidic

- abnormal: from brown to bright red, due to red blood cells (hematuria); cloudy, due to white blood cells (polyuria, infection); dark yellow to orange, due to concentrated urine (contains protein, RBCs, crystals, stones, or casts)

- Drugs and foods may turn urine a different color


Urinalysis (abnormal substances)

- protein (proteinuria)

- glucose (glycosuria)

- Excess epithelial cells

- crystals and stones (excess of calcium)

- WBC casts associated with renal infection (pyelonephritis)

- RBC casts which indicate inflammation of the glomerulus (glomerulonephritis)

- Epithelial cell casts which indicate sloughing of tubular cells (acute tubular necrosis)



burning on urination



UTI moving up to bladder


Serum Creatine and Blood Urea Nitrogen Uses

- serum creatine and BUN are useful indicators of renal function

- used to monitor the progression of renal disease or to screen for occult renal insufficiency

- serum creatine more reliable indicator of renal function than BUN(great indicator for someone w/o kidney disease & if they are dehydrated or not)


Serum Creaine

- end product of muscle metabolism excreted exclusively by the kidney

- normal level is 0.7 to 1.5 mg/dl (in a clinical 1.2 is more common)

- Affected by 2 factors: 1. rate of creatine produced from muscle, which is relatively constant in the absence of a muscle breakdown 2. rate of creatine excreted by the kidney, which is determined primarily by the gfr

- Elevated level indicated a decrease in renal function


Blood Urea Nitrogen

- urea is an end product of protein metabolism excreted primarily by the kidney

- normal level is about 10 to 20 mg/dl

- Elevated level indicates a decrease in renal function, a decrease in fluid volume, and an increase in catabolism and dietary protein intake


Measures of Glomerular Filtration Rate (GFR)

- estimated by measuring the clearance of a filterable substance from the urine

- creatine clearance is frequently used but it is not completely accurate

- Inulin clearance provides a more accurate measure of GFR, but is never used in clinical practice


Diagnostic Tests

- evaluate kdney structure and function

- help determine underlying pathologic processes

- includes Kidney, Ureter, and Bladder Roentgenograpy (KUB), intravenous urography/pyleography (IVP), Radionuclide Studies, Ultrasonography, Computed Tomography (CT), MRI, and a Renal Biopsy


Kidney, Ureter, and Bladder Roentgenography (KUB)

- xray of the abdomen

- gives info on if patient has renal stone, also gives a look at the bowels


Intravenous Urography/Pyelography (IVP)

- iodine containing radiopaque dye is infected into a vein; it then circulated through the kidney and is excreted in the urine

- Rapid series of xrays made as the dye is being secreted

- dye is nephrotoxic, meaning that it is poisonous to the kidneys (can cause renal failure if not handled properly


Radionuclide Studies

- renograms and renal scans which use radioactive isotopes

- renogram: useful for accessing function

- Renal Scan: better at detecting structural anomalies

- Positron emission tomography (PET) or single photon emission computed tomography (SPECT): provide a more dynamic assessment



- Noninvasive, painless procedure that uses high frequency sound waves to image renal structures

- a probe with a transducer inside is held against the bacl and emits ultrasound waves that travel through tissue to the kidney and reflect off of the kidney, back to the probe


Computed Tomography Scan (CT scan)

- combines roentgenography with computer technology; is a noninvasive, and painless procedure

- instead of using road xray beams, Ct uses thin xray beams

- contrasty dyes may be used since the kidneys are deep within the body (if there are stones no dye is needed, if there is a tumor dye is needed)


Magentic Resonance Imaging (MRI)

- painless noninvasive procedure that does not use xrays or radioactive markers

- imager applies a strong magnetic field that causes protons to align themselves with the magnetic field

- contrast dye may be used (gadolinum)


Renal Biopsy

- obtain renal tissue that may be studied to determine the nature and extent of renal disease

- used for diagnosis, management, and prognosis


Diruetic Agents Uses

- drugs that alter the osmolality of the urinary filtrate and oppose the reabsorption of water, resulting in an increase in urine volume

- osmotic diuretics increase osmolality of the filtrate causing more water to remiain in the tubule, which is excreted


Diuretic Agent Types

- Ace inhibitors: inhibit the formation of Angiotensin II and aldosterone

- Loop Diuretics: block the sodium potassium and chloride pumps in the ascending loop of henle

- Thiazide: like diuretics they block sodium reabsorption in the distal convolating tubules

- Potassium wasting diuretics: cause potassium to be excreted in the urine (include osmotic, ace inhibitors, loop and thiazide like)

- Aldosterone Blocking agents are potassium sparing (still cause an increase in urine volume)


Endocrine Functions

- kidneys normally secrete erythopoietin, a growth factor for red cells, and active vitamin D, a necessary cofactor for calcium reabsorption from the intestine

- In chronic renal failure, impaired production of these hormones results in anemia, osteodystrophy, and hypocalcemia



- Peptide growth factor that stimulates erythrocyte development in the bone marrow

- increased release with hypoxia and decreased circulating red cell mass


Vitamin D

- kidnet performs the second hydroxylation of Vitamin D to form 1,25-hydroxylcholecalciferol, the active form of vitamin D necessary for calcium reabsorption from the intesitne

- may also facilitate calcium reabsorption in the kidney tubules