Renal Lab Evaluation

Question 1

Creatinine:

Answer 1

Waste product of protein breakdown excreted by kidneys
Normal range:
men—0.8-1.4
women 0.6-1.2 mg/dL
Increased:
Renal Failure, ingestion of meat, Meds: ACEIs, diuretics, NSAIDS,Muscle disease: muscular dystrophy, rhabdomyolysis
Decreased:
Pregnancy—normal occurrence, Range in pregnancy— 0.4 – 0.6 mg/dL

Question 2

BUN (blood urea nitrogen)

Answer 2

Urea nitrogen is what is formed when protein breaks down
Normal range: 6-20 mg/dL
Increased:
Renal Disease (failure)
Excessive protein breakdown (catabolism- tissue necrosis)
Very high protein diet
GI Bleeding
Decreased:
Liver disease
Starvation

Question 3

BUN/Creatinine Ratio

Answer 3

Normally 10-20:1

Question 4

Glomerular filtration rate (GFR)

Answer 4

Equal to the sum filtration rate of all the functioning nephrons
Normal for men = 130 mL/min/173 m2
Normal for women – 120 mL/min/173 m2
Decreased NORMALY with age
Measured by: Creatinine clearance, Urea clearance, Inulin clearance (exogenous polysaccharide 100% filtered- gold standard for GFR)

Question 5

Cockcroft-Gault Formula (How to calculate GFR)

Answer 5

Measure serum creatinine and estimate GFR to assess renal function w/o urine

Estimated GFR/CCr (mL/min) = [(140 - age) x wgt (kg)]/[72 x SCr]

Multiply results by 0.85 for women

Question 6

Cations Normal Values

Answer 6

Sodium (Na+) 135 - 145 mmol/L

Potassium (K+) 3.8 - 5.5 mmol/L

Question 7

Anions Normal Values

Answer 7

Chloride (Cl-) 98 - 106 mmol/L
Bicarbonate (HCO3-) 21 - 28 mmol/L
(Total CO2) 23 - 30 mmol/L

Question 8

Acid urine (pH < 6.0)

Answer 8

High protein diets
Medications
Uncontrolled diabetes or other causes of metabolic acidosis

Question 9

Alkaline urine:

Answer 9

Normal post-prandial physiology
Diets high in vegetable, milk and other dairy
Medications
UTI

Question 10

Protein Expected results:

Answer 10

Average 40-80 mg protein excreted per day
100 to 150 mg/day is WNL therefore concentration in random urine is 2-8 mg/dL
Proteinuria is the single most important indicator of kidney disease

Question 11

Benign proteinuria

Answer 11

Functional changes: high fever, CHF, strenuous exercise & cold exposure

Question 12

Glucosuria occurs whenever the blood glucose level exceeds the renal threshold:

Answer 12

Approximately 180 mg/dL

Condition may be benign (called renal glycosuria) or pathological (diabetes mellitus)

Question 13

Leukocyte esterase positive test

Answer 13

Pyuria (presence of WBCs in urine)

Bacteriuria/UTI