Kidney Flashcards
Osmolaity Calculation
2(Na) + Glucose/20 + BUN/3
Major functions of Kidney
- Removal of unwanted substances from plasma (waste & surplus)
- Homeostasis (maintain equilibrium of body’s water, electrolytes, and acid/base status)
- Hormonal Regulation
Functional Unit of Kidney
Nephron
Glomerulus
receives & filters blood based on size and charge
Loop of Henle: Descending Loop
permeable to H20
impermeable to Sodium (Na) and Chloride (Cl
Loop of Henle: Ascending Loop
permeable to Sodium (Na) and Chloride (Cl)
Impermeable to H20
Aldosterone acts on what part of the nephron
Distal Convoluted Tubule
Collecting Ducts
What secretes Aldosterone
Adrenal Cortex
Aldosterone reabsorbs
Sodium (Na) and Chloride (Cl)
excretion of Potassium (K) and Hydrogen (H)
ADH acts on
Collecting Ducts
What secretes ADH
Posterior Pituitary
ADH’s Function
Reabsorb Water (H2O) from the collecting ducts
How much blood does the glomerulus filter a minute?
1200 - 1500 ml/min blood filtered
How much filtrate does the Glomerulus produce a minute?
125 - 130 ml/min filtrate produced
Clearance
Volume of plasma that will completely eliminate a measured amount of substance in urine
Conditions triggering ADH secretion
Increased serum osmolality
Decreased blood volume/prssure
Renin secreted by:
juxataglomerular apparatus
Renin Function
Converts Antiotensin I to Antiotensin II
Angiotensin II function
a. vasoconstriction to increase BP
b. proximal tubule reabsorbs Na
c. stimulates aldosterone secretion (by adrenal cortex to reabsorb Na)
d. stimulates ADH secretion (by posterior pituitary to reabsorb H20)
What conditions trigger Aldosterone?
Decreased blood flow
Decreased Sodium
Clearance Calculation for Creatinine
UV/P X 1.73/A
U = urine concentration (creatinine) V = urine volume (creatinine collection) P = plasma concentration (creatinine) 1.73 = (correction for body mass) A = body Surface
Estimated Glomerular Filtration Rate (EGFR):
calculation based on serum creatinine, sex, age, weight, and race
Nephrotic Syndrome Symptoms
Abnormally permeable glomerular membrane (doesn’t reabsorb / lets proteins through)
Lipidurea (fat in urine) Hyperlipidemia (high lipids) General edema Hypoalbuminemia (low albumin) Proteinuria (protein in urine)
Glomerulaonephritis
renal concentrating ability has become dysfunctional
Symptoms: hematuria (blood in urine) proteinuria (protein in urine) decreased GFR Elevated BUN/creatinine serum, Na&H20 retention
GFR indicative of stages of Renal Disease
Normal GFR: > 60 ml/min
Kidney Damage 60-89 ml/min
Moderate 30-59 ml/min
Severe 15-29 ml/min
Renal Failure: < 10 ml/min
Chronic Renal Failure
slow, progressive loss of nephron function
Glomerular Filtration Rate decreases
Glomerular inflammation
Caused by: glomerulonephritis and pyelonephritis
Acute Renal Failure
sudden, sharp decline in renal operation
Glomerular Filtration Rate <10 ml/min
Acute Renal Failure
Hypoxic Insult
Pre-Renal Cause of decline in renal operation
Compromised blood flow, septic, hemorrhagic, cardiac failure
Acute Renal Faiure
Acute Toxic Insult
renal cause of decline in renal operation
hemolytic transfusion rxn, metal poisoning, aminoglycoside toxicity
Post-Renal Failure
Blockage of urine by stones, tumors of prostate or bladder, severe UTI
Significance of BUN/Creatinine Ratio
Urea is reabsorbed in tubules whereas as creatinine is not.
Ratio helps indicate what type of renal disease is present
BUN/Creatine Ratio Values
> 20:1 extrarenal disease (pre or post renal failure)
<10:1 renal disease (glomerular or tubular
Calculation for Total Urea
BUN x 2.14
end product of purine metabolism
Uric Acid
Causes of elevated Uric Acid
- metabolism defects
- increased cell destruction
- renal disease
Analytic Method for Creatine
Jaffe Reaction
- picric acid in alkaline solution reacts with Creatinine
- complex forms orange chromagen
- measure spectrophotometrically
Analytic Method for BUN
UV Enzymatic Reaction
hydrolysis of urea / quantification of ammonia
Urease and L-glutamate dehydrogenase monitors the rate of disappearance of NADH at 340nm
Analytic Method for Uric Acid
Chromogen Spec
- Uric acid oxidized by uricase
- H2O2 produced
- Indicator reactin utilizes peroxidase
- Forms chromogen
- Read spectrophotometrically
Analytic Method for Osmolarity
Freezing Point Depression
- Sample super cooled to -7 degrees and mechanically induced to freeze
- Equilibrium is reached
- Freezing point is measured
(more concentrated = longer to freeze/lower freezing point)
(less concentrated = faster to freeze/higher freezing point
Samples for Creatinine
Urine
EDTA plasma
Heparin
Serum
Samples for BUN
Urine
EDTA plasma
Heparin
Serum
Samples for Uric Acid
Urine
EDTA plasma
Heparin
Serum
Samples for Osmolality
Urine
EDTA plasma
Serum
(particle free)
Steps of 24 Hour Urine
- patient voids bladder and discards (time starts now)
- collect all urine for 24 hours refrigerated
- at 24 hour mark patient voids bladder as final collection (end time
Creatinine Reference Range
Creatinine Critical Values
Normal Serum: 0.4 - 1.2 mg/dl
Critical Serum: > 5.0 mg/dl
Normal Urine: 0.8 - 2.0 g/24hr
Clearance: 75 - 125 ml/min
BUN Reference Range
Normal Serum: 5 - 25 mg/dl
Critical Serum: >90 mg/dl
Uric Acid Normal Serum and Urine Value
Normal Serum: 2.0 - 80.0 mg/dl
Normal Urine 250 - 750 mg/24hr
Serum osmolality normal range
285 to 305
