CPT CODE:

USEFUL FOR:

Diagnosis and treatment of liver, bone, intestinal, and parathyroiddiseases Determining the tissue source of increased alkaline phosphatase(ALP) activity in serum
Differentiating between liver and bone sources of elevated ALP

SPECIMEN REQUIRED:

Draw blood in a plain, red-top tube(s) or a serum gel tube(s). (Hemolyzed specimen is not acceptable.) Spin down and send 1 mL of serum divided into 2 tubes each containing0.5 mL of serum frozen in plastic vial.Note: Patient's age and sex are required on request formfor processing.

TRANSPORT TEMPERATURE:

Frozen\Refrig OK\Ambient NO

CLINICAL INFORMATION:

Alkaline phosphatase (ALP) is present in a number of tissues including liver, bone, intestine, and placenta. The activity of ALP found in serum is a composite of isoenzymes from those sites and,in some circumstances, placental or Regan isoenzymes. Serum ALP is of interest in the diagnosis of 2 main groups of conditions-hepatobiliary disease and bone disease associated with increased osteoblastic activity.  
A rise in ALP activity occurs with all forms of cholestasis, particularly with obstructive jaundice. The response of the liver to any form ofbiliary tree obstruction is to synthesize more ALP. The main siteof new enzyme synthesis is the hepatocytes adjacent to the biliarycanaliculi.
ALP also is elevated in disorders of the skeletal system that involveosteoblast hyperactivity and bone remodeling, such as Paget's disease rickets and osteomalacia, fractures, and malignant tumors.
Moderate elevation of ALP may be seen in other disorders such asHodgkin's disease, congestive heart failure, ulcerative colitis,regional enteritis, and intra-abdominal bacterial infections.

CLINICAL INTERPRETATION:

Total Serum Alkaline PhosphataseALP elevations tend to be more marked (more than 3-fold)in extrahepatic biliary obstructions (eg, by stone or cancer ofthe head of the pancreas) than in intrahepatic obstructions, and the more complete the obstruction, the greater the elevation. With obstruction, serum ALP activities may reach 10 to 12 times the upper limit of normal, returning to normal upon surgical removal of the obstruction. The ALP response to cholestatic liver disease is similar to the response of gamma-glutamyltransferase (GGT), but more blunted. If both GGT and ALP are elevated, a liver source ofthe ALP is likely.  
Among bone diseases, the highest level of ALP activity is encountered in Paget's disease, as a result of the action of the osteoblastic cells as they try to rebuild bone that is being resorbedby the uncontrolled activity of osteoclasts. Values from 10 to 25 times the upper limit of normal are not unusual. Only moderate risesare observed in osteomalacia, while levels are generally normal in osteoporosis. In rickets, levels 2 to 4 times normal may be observed. Primary and secondary hyperparathyroidism are associated with slight to moderate elevations of ALP; the existence and degree of elevation reflects the presence and extent of skeletal involvement. Very high enzyme levels are present in patients with osteogenic bone cancer. A considerable rise in ALP is seen in children following accelerated bone growth.
ALP increases of 2 to 3 times normal may be observed in womenin the third trimester of pregnancy, although the reference intervalis very wide and levels may not exceed the upper limit of normalin some cases. In pregnancy, the additional enzyme is of placentalorigin. Alkaline Phosphatase IsoenzymesLiver ALP isoenzyme is associated with biliary epithelium and iselevated in cholestatic processes. Various liver diseases (primaryor secondary cancer, biliary obstruction) increase the liverisoenzyme.
Liver 1 (L1) is increased in some non-malignant diseases (such as cholestasis, cirrhosis, viral hepatitis and in various biliary and hepatic pathologies). It is also increased in malignancies with hepatic metastasis, in cancer of the lungs and digestive tract and in lymphoma.  
An increase of Liver 2 (L2) may occur in cholestasis and biliary diseases (eg, cirrhosis, viral hepatitis) and in malignancies (eg, breast, liver, lung, prostate, digestive tract) with liver metastasis.
Osteoblastic bone tumors and hyperactivity of os

REFERENCE VALUES:

ALKALINE PHOSPHATASE

      Males

             4 years: 149-369 U/L

             5 years: 179-416 U/L

             6 years: 179-417 U/L

             7 years: 172-405 U/L

             8 years: 169-401 U/L

             9 years: 175-411 U/L

             10 years: 191-435 U/L

             11 years: 185-507 U/L

             12 years: 185-562 U/L

             13 years: 182-587 U/L

             14 years: 166-571 U/L

             15 years: 138-511 U/L

             16 years: 102-417 U/L

             17 years: 69-311 U/L

             18 years: 52-222 U/L

             > or =19 years: 45-115 U/L

      Females

             4 years: 169-372 U/L

             5 years: 162-355 U/L

             6 years: 169-370 U/L

             7 years: 183-402 U/L

             8 years: 199-440 U/L

             9 years: 212-468 U/L

           &n