clinical chem - non-protein nitrogens

non-protein nitrogens

nitrogen containing compounds that are not proteins

non-protein nitrogens

mostly used to monitor renal function

urea

the major excretory product of protein metabolism and is present in highest concentration in the blood

urea

45% of total non-protein nitrogens

urea

end waste product of protein metabolism and generated from protein breakdown

protein degradation

where does urea come from?

blood urea nitrogen (BUN)

refers to urea measurements

nitrogen measurements

assays for urea are based on _____

urea

used to evaluate renal function

azotemia

elevated concentration of urea in the blood

uremia

very high plasma urea concentration accompanied by renal failure

prerenal azotemia

reduced renal blood flow

renal azotemia

decreased renal function

postrenal azotemia

obstruction of urine flow

prerenal azotemia

caused by congestive heart failure, shock, hemorrhage, dehydration

renal azotemia

caused by acute/chronic renal failure, glomerular nephritis, and other renal diseases

postrenal azotemia

caused by renal calculi, pregnancy, tumors of the urinary tract, and congenital abnormalities

prerenal azotemia

condition elevates urea, but creatinine levels stay normal

renal azotemia

condition elevates both urea and creatinine, so ratio appears normal

postrenal azotemia

condition elevates both urea and creatinine level, but ratio appears elevated

urease

enzymatic methods of BUN: hydrolysis of urea by the enzyme _____ followed by the quantification of ammonium ion produced in the reaction

berthelot method

enzymatic method for urea that is colorimetric and used the urease reaction and then nitroprusside to detect NH4-

GLDH

coupled enzymatic reaction for urea that uses the urease reaction with glutamate dehydrogenase, automated

plasma, serum, 24 hour urine

what is the specimen for BUN?

6-20 mg/dL

what is the reference range for plasma or serum for BUN?

C

a patient comes through the ER with right flank pain and hematuria. the doctor orders a BUN and the level comes back as 30 mg/dl. scans show a kidney stone in the patient’s right ureter. what type of azotemia does this patient have?

A. prerenal

B. renal

C. postrenal

creatine

synthesized primarily in the liver from arginine, glycine, and methionine

transported to other tissues, such as muscle, where it is converted to creatine phosphate and serves as a high energy source for muscles

creatinine

once the muscle uses creatine, the waste product is _____

creatinine

released into the circulation at a relatively constant rate that has been shown proportional to an individual’s muscle mass

creatinine

since it is filtered out of the body at a fairly constant rate, it is a good indicator of kidney function

creatinine

increased levels of _____ in the blood suggest glomerulonephritis, polynephritis, acute tubular necrosis, urinary tract obstruction, reduced blood flow ot kidneys

creatinine

low levels of _____ are not common and are not a cause for concern

jaffe reaction

chemical method for creatinine where it reacts with picric acid (yellow) in alkaline solution to form a red-orange chromogen

kinetic jaffe method

chemical method for creatinine where serum is mixed with alkaline picrate and the rate of change in absorbance is measured

serum, plasma, urine

what is the specimen for creatinine?

0.9-1.3 mg/dL

what is the male serum reference range for creatinine?

0.6-1.1 mg/dL

what is the female serum reference range for creatinine?

800-2000 mg/dL

what is the male urine reference range for creatinine?

600-1800 mg/dL

what is the female urine reference range for creatinine?

creatinine clearance

a measure of the amount of creatinine eliminated from the blood by the kidneys, used to gauge renal function

24-hour urine

creatinine clearance is performed using _____ specimen and a serum creatinine sample

97-137 mg/dL

what is the male reference range for creatinine clearance?

88-128 mg/dL

what is the female reference range for creatinine clearance?

D

what does creatinine react with in the jaffe reaction, and what color complex is produced?

A. urease, red-orange

B. picric acid, blue

C. urease, blue

D. picric acid, red-orange

uric acid

end product of purine metabolism

nucleic acid

uric acid is the product of _____ metabolism

monosodium urate

nearly all of the uric acid in plasma is present as _____

urate

in serum/plasma, uric acid is in it ionized form

uric acid

in the collecting tubules of the kidneys _____ is favored

hyperuricemia

elevated uric acid concentrations

gout

a common complex form of arthritis that can affect anyone, caused by buildup of monosodium urate crystals in the joints and tissues

gout

detected in the lab in synovial fluids

MSU crystals

large, needlelike crystals that may be intracellular or extracellular

hyperuricemia

increased catabolism of nucleic acids or cell nuclei, renal disease causing elevated uric acid concentration because filtration and secretion are impaired

lesch nyhan syndrome

cause of hyperuricemia that is an enzyme deficiency that leads to high plasma and urine concentrations of uric acid, occurs in males

hypouricemia

seen secondary to liver disease, defective tubular resorption, overtreatment that inhibits purine synthesis

uricase

enzymatic method for uric acid that is based on _____ reaction in which uric acid is converted to allantoin, end result is a colored compound

heparinized plasma, serum, urine

what is the specimen for uric acid?

uric acid

need to have serum specimen removed from cells quickly to prevent dilution by intracellular contents

3.5-7.2 mg/dL

what is the male reference range for uric acid?

2.6-6.0 mg/dL

what is the female reference range for uric acid?

A

a 32 year old male comes to his primary care doctor with a primary complaint of joint swelling and pain in his left big toe. the doctor notes swelling and redness at the site and orders a uric acid to test for gout. what do you expect this patient’s uric acid level to be?

A. 9.0 mg/dl

B. 4.0 mg/dl

C. 7.1 mg/dl

ammonia

produced in the deamination of amino acids during protien metabolism

severe liver disease

the most common cause of disturbed ammonia metabolism

reyes syndrome

rare but serious acute condition involving extremely high levels of ammonia, causes swelling in the liver and brain, occurs in children and teens recovering from viral infection

aspirin

what is linked to reye’s syndrome?

urea cycle disorders (UCD)

complete lack of enzymes that are responsible for removing ammonia from the blood stream in the urea cycle will result in death shortly after birth, inherited

ammonia

enzymatic method using glutamate dehydrogenase, measuring the coenzyme consumed in the reaction (NADPH) is proportional to ammonia concentration

EDTA and heparin plasma

what is the specimen for ammonia?

ammonia

these samples need to be placed on ice immediately after venous draw because the amino acid degradation continues in the test tube

cigarette smoke

this contamination of the patient increases ammonia levels

19-60 mg/dL

what is the adult reference range for ammonia?

B

a 4 year old female patient presents to the ER unconscious. the patient’s mother explains that her daughter has been sick with the flu and she gave her aspirin for her symptoms. the doctor orders an ammonia level, which comes back as 200 mg/dL. based on this information, what condition does the patient most likely have?

A. flu complications

B. reyes syndrome

C. gout

D. kidney failure