T1: Non-Protein Nitrogens and Glomerular Function Tests (PART1) Flashcards
What are the four non-protein nitrogen compounds?
- Ammonia
- Creatinine
- Urea
- Uric Acid
ESSAY
Urea
- Two specific sources
- Detoxification product of ammonia from the urea cycle
2. Product of dietary protein intake
ESSAY
Urea
- Three sites in the nephron where it is filtered, reabsorbed or secreted
Filtered: freely filtered in glomerulus
Reabsorbed: PCT
Secreted: loops of Henle
ESSAY
Urea
- Relative usefulness for glomerular function assessment compared to creatinine
- the BEST clinical use of BUN measurements lies with concomitant creatinine measurements
ESSAY
Urea
- two principal diagnostic uses of its measurement
Pre renal and post renal azotemia problems
ESSAY
Urea
Reference range
8-26 mg/dL
What are 5 factors that affect blood urea nitrogen (BUN) levels
- State of hydration
- Renal function
- Liver funciona
- Amount of protein in diet
- Amount of protein breakdown body
What are 5 conditions that increase nitrogen load?
- Febrile illness
- Corticosteroid or tetracycline therapy
- Large protein ingestion
- GI bleed with blood absorption in gut
- Elevated thyroid hormone concentration
What are 4 conditions that decrease nitrogen load?
- Low protein diet
- Increased androgens
- Growth hormone
- Pregnancy
What test should be analyzed along with BUN in order to obtain the best assessment of renal function
Creatinine
What 5 pre-renal causes of azotemia due to decreased blood flow to the kidney and decreased urea filtration
- Congestive heart failure
- Shock
- Hemorrhage
- Dehydration
- Marked decrease in blood volume
What is the one cause of renal azotemia?
- Renal Failure
What are the 3 causes of postrenal azotemia that cause decreased excretion of urea?
- Renal lithiasis (stones)
- Tumors of the bladder or prostate
- Severe infections
ESSAY
Creatine
- three specific sources
- kidneys
- liver
- Pancreas
ESSAY
Creatine
- enzyme necessary for conversion of creatine to phosphocreatine
Creatine Kinase
ESSAY
Creatinine
- one specific source
anhydride byproduct of creatine
ESSAY
Creatinine
- renal handling
Filtered: freely
Reabsorbed: not reabsorbed by tubules
Excreted: at constant rate with insignificant secretion
ESSAY
Creatinine
- three reasons why creatinine’s measurement may be used to estimate the glomerular filtration rate
- Freely filtered by glomeruli
- Not reabsorbed by tubules
- Excreted at constant rate with insignificant secretion
ESSAY
Creatinine
- usefulness for detecting early glomerular dysfunction
- Detect kidney disease (decreases as disease worsens)
- Monitor patients with known renal disease
- Plan life sustaining therapy for those with end-stage renal disease
- Adjust drug dosage for agents excreted by kidney
- Detect kidney disease (decreases as disease worsens)
ESSAY
Creatinine
- Reference range for men and women
men: 0.9-1.5 mg/dL
women: 0.8-1.2 mg/dL
Four clinical uses of GFR calculations
- Detect kidney disease (decreases as disease worsens)
- Monitor patients with known renal disease
- Plan life sustaining therapy for those with end-stage renal disease
- Adjust drug dosage for agents excreted by kidney
What chemical creatinine method has creatinine reacting directly with picrate ions under alkaline conditons to form a red-orange complex?
Principle of Jaffe creatinine method
Specific reagents used in Jaffe creatinine method
alkaline picrate ions
Three enzymes used for enzymatic determination of creatinine
- Creatininase
- Creatininase and creatinase
- Creatinine iminohydrolase
Normal ratio of the BUN : Creatinine ratio
12 - 20 : 1
Specific cause for a constant ratio of 10:1-15:1 in the BUN:creatinine ratio
patient probably has intrinsic renal disease
