LABORATORY TEST ALKALINE PHOSPHATASE(ALP)

                                     

                                

                                                         Structure of alkaline phosphatase

NORMALRANGE

  

ADULT MALES-    53-128 U/I
ADULT FEMALES-   42-98 U/I

PEDIATRIC NORMAL RANGE
INfants -        150-420 IU/L (37⁰C)
Children-     100-320 IU/L (37⁰C)

SAMPLE REQUIRED

2ml Random serum sample

CLINICAL SIGNIFICANCE

ALP is one of the enzymes present in serum that is capable of transporting phosphate groups across cell membrane.It is most active between pH 8 and 10 . The serum or plasma ALP is estimated to investigate diseases of the liver or bone, especially in cases of billiary obstruction , tumors, hydatid cyst and abscesses. Alkaline phosphatase is an enzyme in all tissues. Tissues with particularly high concentrations include liver, bile ducts , placenta and bone. Since damaged or diseased tissue releases enzymes into the blood, serum ALP measurements can be abnormal in many conditions, including bone disease and liver disease.

ALP is a marker for billiary dysfunction. The values are increased;

• Greater than twice the normal in complete obstructive cholestasis in proportion to increase in serum bilirubin.
• More than 10 times if infection supervenes in the case of complete billiary obstruction 
• More than two times in partial obstruction , out of proportion to increased conjugated bilirubin.Serum alkaline phosphatase levels fall to normal ( more slowly  compared to bilirubin), once the cholestasis is relieved.
• A moderate rise in the enzyme activity is observed in osteomalacia and rickets.
• Low serum ALP values are occasionally encountered in hypothyroidism, malnutrition, severe chronic nephritis and celiac disease.

What abnormal results mean;

Increased levels;

• Anemia
• Biliary obstruction
• Bone disease
• Healing fracture
• Heptitis
• Hyperthyroidism
• Hyperparathyroidism
• Leukemia
• Liver diseases
• Cirrhosis
• Gilbert syndrome
• Fatty metamorphosis of livers
• Sepsis. certain viral disease ; infectious mononucleosis, cytomegalovirus infections
• Postoperative cholestasis, Pancreatitis , carcinoma of pancreas, cystic fibrosis
• Pulmonary infarct
• Fanconi syndrome
• Osteoblastic bone cancers
• Ostwomalacia
• Paget's disease
• Rickets
• Hypervitaminosis D
• Familial hyperphosphatasemia.

Decreased levels;

• Malnutrition
• Protien deficiency
• Pernicious anemia
• Hypophosphatasia

Additional conditions under which the test may be performed

• Alchoholic liver disease ( hepatitis / cirrhosis )
• Alcoholism
• Biliary structure
• Giant cell ( temporal , cranial ) arteritis
• Multiple endocrine neoplasia ( MEN ) II
• Renal cell carcinoma

SPECIAL CONSIDERATIONS

The ALP levels vary with age and gender. It is normal for young children experiencing rapid growth and for pregnant women to high levels of ALP.