SPECIMEN TYPE

Serum (blood sample collected to a Plain tube)

CLINICAL SIGNIFICANCE

ALT is specific for hepatocytes. In viral hepatitis and other forms of liver disease associated with hepatic necrosis, serum ALT is elevated even before the clinical signs and symptoms of the disease appear. Although both AST and ALT elevate in the presence of any form of liver cell injury, ALT is the more liver-specific marker. Serum elevations of ALT are rarely observed in conditions other than parenchymal liver disease. Also, ALT elevation persists longer than AST elevation.

INTERPRETATION

Elevation of ALT is seen in parenchymal liver diseases characterized by destruction of hepatocytes. Values are typically at least 10 times above the normal range. Levels may reach values as high as 100 times the upper reference limit, although 20- to 50-fold elevations are most frequently encountered. In infectious hepatitis and other inflammatory conditions affecting the liver, ALT is characteristically as high as or higher than AST.

ALT:AST ratio, which normally and in other condition is less than 1, becomes >1 in liver parenchymal injury.

SPECIMEN TYPE

Serum (blood sample collected to a Plain tube)

CLINICAL SIGNIFICANCE

Albumin constitutes 55% to 65% of total plasma protein. It maintains oncotic pressure, and is involved in the transport and storage of a wide variety of ligands, such as calcium bilirubin. Hypoalbuminemia can be caused by impaired synthesis due either to liver disease (primary) or low protein intake/ malabsorption of amino acids (secondary), increased renal excretion (eg, nephrotic syndrome), and increased catabolism as a result of tissue damage and inflammation.

INTERPRETATION

When the serum albumin values fall below 2.0 g/dL, edema is usually present. Hyperalbuminemia is of little diagnostic significance except in the case of dehydration.

SPECIMEN TYPE

Serum (blood sample collected to a Plain tube)

CLINICAL SIGNIFICANCE

The clinically significant origins of ALP include; liver, bone osteoblasts, small intestinal mucosa, proximal convoluted tubules of the kidney, and placenta. The clinically significant origins of ALP include; liver, bone osteoblasts, small intestinal mucosa, proximal convoluted tubules of the kidney, and placenta. The liver isoform mainly contributes to the ALP activity observed in the serum in a healthy adult.

A rise in the ALP occurs with all forms of cholestasis, particularly with obstructive jaundice. It is also elevated in diseases of the skeletal system, such as Paget disease, hyperparathyroidism, rickets, and osteomalacia, as well as with fractures and malignant tumors. A considerable rise in the ALP observed in children is due to the physiological increase in osteoblast activity in growing bone.

Males
0 - 14 days		: 83-248 U/L
15 days to <1 year	: 122-469 U/L
1 to <10 years		: 142-335 U/L
10 to <13 years		: 129-417 U/L
13 to <15 years		: 116-468 U/L
15 to <17 years		: 82-331 U/L
17 to <19 years		: 55-149 U/L
⋝19 years		: 40-129 U/L

Females
0 - 14 days		: 83-248 U/L
15 days to <1 year	: 122-469 U/L
1 to <10 years		: 142-335 U/L
10 to <13 years		: 129-417 U/L
13 to <15 years		: 57-254 U/L
15 to <17 years		: 50-117 U/L
⋝17 years		: 35-104 U/L
Pregnant females	: average ALP levels typically mount to about 2-3 times its pregestational value

INTERPRETATION

Increases in serum ALP activity commonly originate from liver and/or bone. Consequently, serum ALP measurements are of particular interest in the investigation of hepatobiliary diseases and bone diseases associated with increased osteoblastic activity.

Any form of biliary tree obstruction induces the synthesis of ALP by hepatocytes. The increase is more notable (>4-fold the upper reference limit) in extrahepatic obstruction (eg, by stone, by cancer of the head of the pancreas) than in intrahepatic obstruction. Serum enzyme activities may reach 10 to 12 times the URL and usually return to baseline on surgical removal of the obstruction. A similar increase is seen in patients with advanced primary liver cancer or widespread secondary hepatic metastases.

Liver diseases that principally affect parenchymal cells, such as infectious hepatitis, typically show only a moderate (<3-fold) rise in the ALP levels. Intestinal ALP isoenzyme is normally cleared by the hepatocytes, thus often increases in patients with liver cirrhosis.

SPECIMEN TYPE

Serum (blood sample collected to a Plain tube)

CLINICAL SIGNIFICANCE

Amylase is produced primarily by the exocrine pancreas. Amylases also are produced by the salivary glands, small intestine mucosa, ovaries, placenta, liver, and fallopian tubes. Pancreatic and salivary isoenzymes contribute to the serum amylase activity.

⋜1 month	: 0-6 U/L
1 - 6 months	: 1-17 U/L						
7 - 12 months	: 6-44 U/L						
1 - 3 years	: 8-79 U/L						
4 - 17 years	: 21-110 U/L						
⋝18 years	: 28-100 U/L

INTERPRETATION

In acute pancreatitis, a transient rise in serum amylase activity occurs within 2 to 12 hours of onset and the levels typically return to normal by the 3^rd or 4^th day. Serum amylase levels peak around 12 to 72 hours from the onset typically by 4-6-fold rise. The magnitude of the elevation of serum enzyme activity is not related to the severity of pancreatic involvement. Normalization is not necessarily a sign of resolution. If acute pancreatitis is associated with hyperlipidemia, serum amylase activity may be spuriously normal due to analytical interference by lipids.

Because it is produced by several organs, amylase is not a specific indicator of pancreatic function. Elevated levels also may also be seen in nonpancreatic pathologies such as mumps, salivary duct obstruction, ectopic pregnancy, and intestinal obstruction/infarction.

SPECIMEN TYPE

Serum (blood sample collected to a Plain tube)

CLINICAL SIGNIFICANCE

AST is found in high concentrations in liver, heart, skeletal muscle, kidney, and red blood cells (RBC). It has 2 isoforms; cytoplasmic and mitochondrial. The cytoplasmic isoform is mainly released into blood in mild tissue injury, while severe tissue damage results in more mitochondrial isoform being released. High levels of AST can be found in cases such as myocardial infarction and acute liver disease. Slight to moderate elevation of AST is seen in muscular dystrophy, dermatomyositis, acute pancreatitis, and crush injury to muscles.

INTERPRETATION

Elevated AST values are seen in parenchymal liver diseases characterized by destruction of hepatocytes, typically rising above >10-fold of UNL. In infectious hepatitis and other inflammatory conditions affecting the liver, ALT is characteristically as high as or higher than AST. AST levels are usually elevated before clinical signs and symptoms of disease appear. 5-10 fold elevations of both AST and ALT occur in patients with primary or metastatic carcinoma of the liver, with AST usually being higher than ALT, but levels are often normal in the early stages of malignant infiltration of the liver. Elevated AST values may also be seen in disorders affecting the heart, skeletal muscle, and kidney.

ALT:AST ratio, which normally and in other conditions is less than 1, becomes >1 in liver parenchymal injury.