Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
The liver, located in the right upper portion of the abdominal cavity just
beneath the right side of the rib cage, has many vital functions. Briefly, some
of these functions are:
Detoxification of blood
Production of important clotting factor and other important proteins
Metabolizing (processing) medications and nutrients
Liver blood tests are some of the most commonly performed blood tests. These tests can assess liver functions or liver injury. An initial step in detecting liver damage is a simple blood test to determine the presence of certain liver enzymes (proteins) in the blood. Under normal circumstances, these enzymes reside within the cells of the liver. But when the liver is injured for any reason, these enzymes are spilled into the blood stream. Enzymes are proteins that are present throughout the body, each with a unique function. Enzymes help to speed up (catalyze) routine and necessary chemical reactions in the body.
Among the most sensitive and widely used liver enzymes are the
aminotransferases. They include aspartate aminotransferase (AST or SGOT) and
alanine aminotransferase (ALT or SGPT). These enzymes are normally contained
within liver cells. If the liver is injured or damaged, the liver cells spill
these enzymes into the blood, raising the enzyme levels in the blood and
signaling liver disease.
Other blood tests pertaining to the liver are measurements of some of the other enzymes found the liver. In addition to AST and ALT,
alkaline phosphatase, 5' nucleotidase, and gamma-glutamyl transpeptidase (GGT) are other enzymes located in the liver. The focus of this article is mainly on the most common liver enzymes, AST and ALT.
What are the aminotransferases?
The aminotransferases catalyze chemical reactions in which an amino group
from one amino acid (amino acids are building blocks of proteins) is transferred from a donor molecule to a recipient molecule. Hence, the names "aminotransferases."
Medical terms can sometimes be confusing, as is the case
with these enzymes.
Another name for aminotransferase is
transaminase.
The enzyme aspartate aminotransferase (AST) is also known as serum
glutamic oxaloacetic transaminase (SGOT).
Alanine aminotransferase (ALT) is also known as
serum glutamic pyruvic transaminase (SGPT).
To put matters
briefly, AST = SGOT and ALT = SGPT.
Normally, where are the aminotransferases?
AST (SGOT) is normally found in a
variety of tissues
including liver, heart, muscle, kidney, and brain. It is
released into the serum when any one of these tissues is damaged. For example,
its level in serum rises in
heart
attacks or with muscle disorders. It is therefore, not a
highly specific indicator of liver injury as it can occur from other injured tissues.
ALT (SGPT) is, by contrast, normally found largely in
the liver. This is not to say that it is exclusively
located in liver, but that is where it is most concentrated.
It is released into the bloodstream as the result of liver
injury. Thus, it serves as a fairly specific indicator
of liver status.
Medical Author: Leslie J. Schoenfield, M.D., Ph.D. Medical Editor: Jay W. Marks, M.D.
The liver is the largest solid organ in the body. I think a lot of people
probably know that. But they may not know that it is also the largest gland in
the body. You see, the liver is also considered a gland because, among its
various functions, it makes and secretes bile. (Just for your reference, the
stomach and intestine are large hollow organs. Glands are organs or parts of
organs that make and secrete substances. And bile is a fluid that both aids in
digestion and transports fats as well as waste products into the intestine.)
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