Potassium ferricyanide (ml) 1 11111111
Mix and read the absorbance at 520 nm26.6 Calculations
The enzyme activity is calculated in terms of King-Armstrong unit (KAU). One
KAU is defined as 1 U of ALP as that liberating 1 mg of phenol from substrate/
15 min/100 ml serum. Plot the graph between OD and the amount of phenol. The
activity can also be calculated as below:
ALPactivity¼ODof testðÞcontrol amount of phenolðÞμg 100
ODof standardvolume of sample mlðÞ 1000
¼x KAU=dl or x U=dl26.7 Clinical Significance...............................
Normal serum ALP levels in adults are 3–14 U/dl or 30–120 U/L. The tissues such as
the liver, bone, and placenta possess very high amounts of ALP activity. Increase in
serum ALP activity is usually associated with hepatobiliary obstruction (all forms of
jaundice except hemolytic jaundice). In hepatobiliary disease, the concentration of
ALP is increased due to defect in excretion of ALP through bile. ALP mainly
produced in bone tissue reaches to the liver and excreted through bile. Increased
ALP levels are also observed in increased osteoblastic activity, rickets, hyperthy-
roidism, and bone disorders. A small increase in ALP activity may also occur in
congestive heart failure, intra-abdominal bacterial infections, and intestinal diseases.
Small increase may also be observed in multiple myeloma and impaired calcium
absorption. The elevation of ALP is more marked in extrahepatic obstruction
(gallstone, cancer of the head of the pancreas, etc.) than intrahepatic obstruction.
Decrease in serum ALP is observed during severe anemia, celiac disease, zinc and
magnesium deficiency, scurvy, cretinism, hypothyroidism, and hypophosphatemia.
26.7 Clinical Significance 109