Creatinine In Serum/plasma

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Contents 1 Indications 2 Reference-interval 3 Principle 4 Clinical-significance 5 Increases 6 Decreases 7 Specimen 8 More General Terms 9 Additional Terms 10 References

Indications

• assessment of renal disease ( renal function)

Reference-interval

• 0.6-1.4 mg/dL, 53-106 umol/L (adult)
• 0.3-0.6 mg/dL, 27-53 umol/L (children < 2 years)
  

• * Conversion factor mg/dL to umol/L = 88.4

Principle

• See creatinine in serum/ plasma/urine

Clinical-significance

• Serum creatinine & urinary creatinine excretion are a function of lean body mass in normal persons & show little or no response to dietary changes. The serum creatinine is higher in men than in women. A small amount of creatinine in urine is due to tubular secretion. Serum creatinine & a 24 hour urine creatinine excretion can be used to estimate the glomerular filtration rate.

Increases

• decreased glomerular filtration

• acute or chronic renal failure
• urinary tract obstruction
• reduced renal blood flow
• shock
• dehydration

• increases independently of glomerular filtration

• ketoacidosis ( acetoacetate: interference with Jaffe reaction)
• massive rhabdomyolysis
• high meat intake
• supplementary creatine
• certain pharmaceutical agents

• inhibition of tubular secretion

• probenicid
• cimetidine
• trimethoprim

• interference with Jaffe reaction

• cefoxitin (possibly other cephalosporins)
• ketone bodies
• isopropyl alcohol
• methanol
• ascorbate
• barbiturates
• glucose
• levodopa
• methyldopa

• flucytosine
• amphotericin B ( in vivo effect)
• kanamycin ( in vivo effect)

Decreases

• debilitation
• decreased muscle mass
• N-acetylcysteine
• exercise may cause an increased creatinine clearance*
  

• * creatinine clearance is unreliable if the urine flow is low.

Specimen

• The recommended specimen is 10 uL of serum or plasma
  
• Serum or Plasma Specimens: Collect by standard venipuncture technique. No special patient preparation is necessary. Lithium or sodium heparin may be used as an anticoagulant for plasma specimens. Special Precautions: Potassium oxalate/ sodium fluoride, citrate, & EDTA should not be used as anticoagulants. Remove serum or plasma promptly from the clot or cells. Refrigerate specimens at 2-8 degrees C if not analyzed within 4 hours, or freeze specimens at -18 degrees C if analysis is delayed beyond 48 hours. Do not use specimens obtained through catheters used to infuse hyperalimentation fluid. Urine Specimens: Collect specimens by standard laboratory procedure. Keep specimens refrigerated until analysis. Dilute each specimen 40-fold with reagent grade water (1 mL patient plus 19mL of water, then take 1 mL of this dilution & add 1 mL of water) before analysis. Multiply results by 40 to obtain the creatinine value. Dynamic range for urine CREA is 0.1 - 16.5 mg/dL.
  
• See creatinine in serum/ plasma/urine
  
• Minimum sample size is 0.5 mL; with an optimum size of 1.0 mL or larger.

More General Terms

• creatinine in body fluid
• renal function tests; renal function panel

Additional Terms

• creatinine
• creatinine clearance

References

1. Kodak Ektachem 700 Analyzer Operator's Manual, Kodak Clinical Products, Rochester, New York.
2. Kodak Ektachem Slide Package Inserts, Kodak Clinical Products Rochester, New York.
3. Kodak Ektachem Training Manual, Kodak Clinical Products, Rochester, New York.
4. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 620.
5. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998.
6. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 11.
7. Prescriber's Letter 9(5):28 2002

creatinine in serum/plasma