NPN compounds

Question 1

Explain the chemical structure, synthesis and mode of excretion of urea

Answer 1

Structure: CO(NH2)2
synthesized in the liver from ammonia and CO2 from deamination of proteins.
Excreted by the kidneys (40% is reabsorbed

Question 2

Discuss disease states and disorders associated with urea measurement

Pre-renal causes

Answer 2

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

Question 3

Discuss disease states and disorders associated with urea measurement

Renal causes

Answer 3

Decrease renal function causes ncreased blood urea due to poor excretion
causes: acute/chronic renal failure, glomular nephritis, tubular necrosis (lack of oxygen)

Question 4

Discuss disease states and disorders associated with urea measurement

Post-renal causes

Answer 4

Obstruction of urine flow
Causes: renal calculi, tumors, severe infection

Question 5

Discuss disease states and disorders associated with urea measurement

Decreased formation (liver disease)

Answer 5

Lack of synthesis
causes: liver disease

Question 6

Discuss disease states and disorders associated with urea measurement

Over-hydration; dilution

Answer 6

Too much water dilutes and increases reabsorption

Question 7

Discuss disease states and disorders associated with urea measurement

End stage renal disease

Answer 7

Kidneys don’t work or are shut down. no excretion

Question 8

Explain the chemical structure, synthesis and mode of excretion of creatinine

Answer 8

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

Question 9

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

Answer 9

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

Question 10

State the reference range and explain the usefulness of the BUN/Creat ratio

Answer 10

Use: Understand renal health
BUN/creatinine
ref ranges: BUN 7-20 mg/dl
creatinine .7-1.2 mg/dl

Question 11

Discuss disease states and disorders associated with creatinine measurement

Muscle wasting disease

Answer 11

Low serum Cr levels result in low muscle mass and difficulty building more.

Question 12

Discuss disease states and disorders associated with creatinine measurement

Renal disease

Answer 12

Decreased GFR (glomular filtration rate) shows increase in sCr, shows decrease in kidney function.

Question 13

Use protocol for performing creatinine clearance test

Answer 13

(Urine Creatinine/plasma creatinine) X (urine volume/time (minutes)) X (1.73/BSA)

Question 14

Recognize factors that can influence eGFR results

Answer 14

(age, muscle mass, gender, race)

Question 15

Explain the chemical structure, synthesis and mode of excretion of uric acid

Answer 15

Structure: Breakdown product of purine metabolism
Synthesis: made in the liver
excreted: kidneys. 98% reabsorbed in PCT. some excreted in DCT.

Question 16

Discuss methodologies for uric acid

Answer 16

uricase converts to allantoin, with abs of 293 nm

Question 17

Discuss disease states and disorders associated with uric acid measurement

Renal disease

Answer 17

Increases levels of UA in blood due to poor excretion and filtration.

Question 18

Discuss disease states and disorders associated with uric acid measurement

Gout

Answer 18

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

Question 19

Discuss disease states and disorders associated with uric acid measurement

Increased cell turnover

Answer 19

Hyperuricemia.
Secondary to liver disease
Defective renal tubular absorption
Fanconi’s Syndrom associated

Question 20

Explain the chemical structure, synthesis and mode of excretion of ammonia

Answer 20

synthesis: Deamination of amino acids, digestion in intestines, muscle use.
Consumed by parenchymal cells of liver. converted to Urea

Question 21

Discuss methodologies for ammonia

Answer 21

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

Question 22

Discuss disease states and disorders associated with uric acid measurement

Reyes Syndrome

Answer 22

Commonly seen in children
proceeded by viral infection treated with asprin
severe fatty infiltration of liver
Why you never give kids asprin

Question 23

Discuss disease states and disorders associated with uric acid measurement

Fanconi’s syndrome

Answer 23

Pathological condition of the proximal renal tubes
Products are passed in the urine instead of reabsorbed, leading to deficiencies
Inherited condition

Question 24

Discuss disease states and disorders associated with ammonia measurement

Liver disease

Answer 24

Most common cause of abnormal ammonia levels
ammonia not being removed from circ
elevated levels of ammonia neurotoxic. can cause encephalopathy and coma