Creatinine

Creatinine

Synonym - Specimen - Reference Value - Method Description - Indications - Interpretation

Synonym : Cr 

Specimen : Serum or Plasma 

Reference Value : 

Method : Spectrophotometry

Description : 

Creatinine is the end product of creatine metabolism .

Creatine residues almost exclusively in the skeletal muscle , where it participates in energy- requiring metabolic reactions . In these processes , a small amount of creatine is irreversibly converted to creatinine , which then circulates to the kidneys and is excreted . 

The amount of creatinine generated in an individuals is proportional to the mass of skeletal muscle present and remains fairly constant , unless there is massive muscle damage resulting from crushing injury or degenerative muscle disease . 

Creatinine values also decrease with age owing to diminishing muscle mass . 

Blood urea nitrogen (BUN) is often ordered with creatinine for comparison . 

The (BUN) / Creatinine ratio is also useful indicator of disease . The ratio should be between 10:1 and 20 : 1 . Creatinine is the ideal substance for determining renal clearance because a fairly constant quantity is produced within the body . The creatinine clearance test measures a blood sample and a urine sample to determine the rate at which the kidneys are clearing creatinine from the blood , this accurately reflects the glomerular filtration rate . 

Indications 

- Evaluate known or suspected impairment of renal function

  ( Decreased glomerular filtration rate (GFR)  

Interpretations : 

Increased in 

1 - Renal disease , acute and chronic renal failure 

2 - Congestive heart failure 

3 - Dehydration 

4 - Acute myositis 

5 - Hyperthyroidism 

6 - Shock 

Decreased in : 

1 - Decreased muscle mass owing to debilitating disease or increasing age 

2 - Inadequate protein intake 

3 - Liver disease ( sever ) due to decreased creatine production . 

4 - Muscular dystrophy .