Nonprotein Nitrogenous Compounds

Question 1

Urea

Answer 1

Major nitrogen containing-compound in blood, excreted by kidneys

Increased serum: renal failure, glomerular nephritis, urinary tract obstruction, CHF, dehydration, increased protein catabolism
Decreased serum: liver disease, vomiting, diarrhea, malnutrition

Urease/GLDH method to oxidize NADH to NAD+

Ref. range = 6-20 mg/dL

Question 2

Creatinine

Answer 2

Excreted by kidneys, not reabsorbed
Increased serum: renal disease/failure

Jaffe method: creatinine + picric acid = red compound
Enzymatic method: oxidizes indicator

Male ref. range = 0.9-1.3 mg/dL
Female ref. range = 0.6-1.1 mg/dL

Question 3

GFR from Creatinine

Answer 3

((U x V)/P) x (1.73 m2/SA)
P = plasma cre. 
U = urine cre.
V = volume 
SA = body surface area

Male ref. range = 105 +- 20 mL/min/1.73 m2
Female ref. range = 95 +- 20 mL/min/1.73 m2

Question 4

Uric acid

Answer 4

Major waste product of purine catablolism, regulated by kidneys

Increased serum: gout, renal disorders, treating myeloproliferative disorders, lead poisoning, lactic acidosis, toxemia of pregnancy, Lesch-Nyhan syndrome
Decreased serum: liver disease, tubular reabsorption disorders, drug induced

Chemical method = form tungsten blue
Enzymatic = form quinine-monoimine dye (293 nm)

Male ref. range = 3.5-7.2 mg/dL
Female ref. range = 2.6-6.0 mg/dL

Question 5

Ammonia

Answer 5

Produced by deamination of amino acids, liver converts to urea for excretion (increase in liver cell malfunction)
Keep sample on ice

Ref. range = 11-32 umol/L