NPN compounds Flashcards
Explain the chemical structure, synthesis and mode of excretion of urea
Structure: CO(NH2)2
synthesized in the liver from ammonia and CO2 from deamination of proteins.
Excreted by the kidneys (40% is reabsorbed
Discuss disease states and disorders associated with urea measurement
Pre-renal causes
Reduced blood flow so less urea filtered.
Causes: anything decreasing blood flow like congestive heart failure, shock, hemorrhage, dehydration, burns
High protein diet or increase catabolism
Discuss disease states and disorders associated with urea measurement
Renal causes
Decrease renal function causes ncreased blood urea due to poor excretion
causes: acute/chronic renal failure, glomular nephritis, tubular necrosis (lack of oxygen)
Discuss disease states and disorders associated with urea measurement
Post-renal causes
Obstruction of urine flow
Causes: renal calculi, tumors, severe infection
Discuss disease states and disorders associated with urea measurement
Decreased formation (liver disease)
Lack of synthesis
causes: liver disease
Discuss disease states and disorders associated with urea measurement
Over-hydration; dilution
Too much water dilutes and increases reabsorption
Discuss disease states and disorders associated with urea measurement
End stage renal disease
Kidneys don’t work or are shut down. no excretion
Explain the chemical structure, synthesis and mode of excretion of creatinine
Structure: Waste product of creatine and creatine phosphate
Synthesis: creatine is made in the liver. converted into creatine phsophate. then converted into waste product creatinine
Excreted in urine
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/sources of error, and the usefulness of the creatinine assay
This question sucks and i hate it.
Creatine kinase uses ATP to create creatine phosphate. that’s converted into creatinine through loss of the phsphate group.
sampled by: urine testing
ref ranged: men: 88-128 mL/min. Women: 97-137 mL/min
assay helps us understand renal function
State the reference range and explain the usefulness of the BUN/Creat ratio
Use: Understand renal health
BUN/creatinine
ref ranges: BUN 7-20 mg/dl
creatinine .7-1.2 mg/dl
Discuss disease states and disorders associated with creatinine measurement
Muscle wasting disease
Low serum Cr levels result in low muscle mass and difficulty building more.
Discuss disease states and disorders associated with creatinine measurement
Renal disease
Decreased GFR (glomular filtration rate) shows increase in sCr, shows decrease in kidney function.
Use protocol for performing creatinine clearance test
(Urine Creatinine/plasma creatinine) X (urine volume/time (minutes)) X (1.73/BSA)
Recognize factors that can influence eGFR results
(age, muscle mass, gender, race)
Explain the chemical structure, synthesis and mode of excretion of uric acid
Structure: Breakdown product of purine metabolism
Synthesis: made in the liver
excreted: kidneys. 98% reabsorbed in PCT. some excreted in DCT.
Discuss methodologies for uric acid
uricase converts to allantoin, with abs of 293 nm
Discuss disease states and disorders associated with uric acid measurement
Renal disease
Increases levels of UA in blood due to poor excretion and filtration.
Discuss disease states and disorders associated with uric acid measurement
Gout
More prevalent in men
UA > 6 mg/dl
increased risk of renal calculi
inflam of joints due to precipitation of sodium urate crystals in tissues
25-30% experience hyperuricemia
Discuss disease states and disorders associated with uric acid measurement
Increased cell turnover
Hyperuricemia.
Secondary to liver disease
Defective renal tubular absorption
Fanconi’s Syndrom associated
Explain the chemical structure, synthesis and mode of excretion of ammonia
synthesis: Deamination of amino acids, digestion in intestines, muscle use.
Consumed by parenchymal cells of liver. converted to Urea
Discuss methodologies for ammonia
Testng difficult due to volatility
Gutamate dehydrogenase used to measure NADH consumption. light absorbance decreases and NADH is oxidized
Direct ISE - potential measured in media as ammonia diffuses through
Discuss disease states and disorders associated with uric acid measurement
Reyes Syndrome
Commonly seen in children
proceeded by viral infection treated with asprin
severe fatty infiltration of liver
Why you never give kids asprin
Discuss disease states and disorders associated with uric acid measurement
Fanconi’s syndrome
Pathological condition of the proximal renal tubes
Products are passed in the urine instead of reabsorbed, leading to deficiencies
Inherited condition
Discuss disease states and disorders associated with ammonia measurement
Liver disease
Most common cause of abnormal ammonia levels
ammonia not being removed from circ
elevated levels of ammonia neurotoxic. can cause encephalopathy and coma
