Creatinine

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Latest Edit: Hector 2014-03-24 (EDT)

See Also Lab Tests

Creatinine is commonly used as a measurement of kidney function. Creatinine is a waste product produced by muscles due to the breakdown of a compound called creatine phosphate. Creatine phosphate is a storage depot for muscle energy and is produced primarily from the contraction of muscle. The production of creatine phosphate is dependent on the muscle mass of the person, and is removed from the body by the kidneys.[1],[2]

Discussion

  • Serum creatinine levels can be affected by the muscle mass of the individual.
  • Patients with increased muscle mass may therefore have slightly higher creatinine levels than patients with decreased muscle mass (older adults and children).
  • Creatinine is often used with BUN to assess impaired kidney function and is considered to be a more specific and sensitive test indicator of renal disease than BUN.

Patient Preparation

  • No fasting is required.
  • Factors which can cause increased levels
  • High ascorbic acid intake, a diet high in meat
  • Drugs: aminoglycosides (e.g., gentamicin), cimetidine, heavy-metal chemotherapeutic agents (e.g., cisplatin), and other nephrotoxic drugs such as cephalosporins (e.g., cefoxitin).
  • Factors which can cause decreased levels
Drugs: Cephalosporin antibiotics, histidine, and quinidine compounds

Clinical Implications

Ranges: The following are the reference ranges for this lab. However, lab ranges can vary by laboratory and country. [2]

Standard U.S. Units Standard International Units
Conventional Laboratory Range 0.6-1.5 mg/dL 53.0-132.6 umol/L
Optimal Range 0.8-1.1 mg/dL 70.7-97.2 umol/L
Alarm Ranges > 1.6 mg/dL > 141.4 umol/L

High levels indicate:

  • Male:
  • Female:

Low levels indicate:

  • Muscle atrophy/ or nerve-muscle degeneration
  • Other conditions: Little metabolism in the muscles indicating a need for exercise, liver disease, muscular dystrophy, multiple sclerosis
  • Sedentary lifestyle
  • Malnutrition / debility

Associated Tests

References

  1. Pagana Kathleen D, Pagana Timothy J, (1998) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby, Inc
  2. 2.0 2.1 Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain Cite error: Invalid <ref> tag; name "weatherby" defined multiple times with different content