Liver blood test

 Liver blood test

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 the liver disease.

 Aminotransferases

The aminotransferases catalyze chemical reactions in which an amino group (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); and 

·                          alanine aminotransferase (ALT) is also known as serum glutamic pyruvic transaminase (SGPT).

To put matters briefly, AST = SGOT and ALT = SGPT.

 Normal levels of AST and ALT

The normal range of values for AST (SGOT) is from 5 to 40 units per liter of serum (the liquid part of the blood).

The normal range of values for ALT (SGPT) is from 7 to 56 units per liter of serum.

The ranges of AST and ALT numbers may differ slightly depending on the technique and protocols used by different laboratories. However, normal reference ranges are routinely provided by each laboratory and printed in the report.

Medications cause abnormal aminotransferase levels

A host of medications can cause abnormal liver enzymes levels.

Examples include:

Pain relief medications such as:

·                          aspirin, 

·                          acetaminophen (Tylenol), 

·                          naproxen (Narcosis, Nap élan, Anaprox, Aleve), 

·                          diclofenac (Voltaren, Cataflam, Voltaren-XR), and 

·                          phenylbutazone (Butazolidine)

Anti-seizure medications such as:

·                          phenytoin (Dilantin), 

·                          valproic acid (Depakote, Depakote ER, Depakene, Depacon), 

·                          carbamazepine (Tegretol, Tegretol XR, Equertro), and 

·                          phenobarbital

Antibiotics such as:

·                          tetracyclines, [for example, tetracycline (Achromycin)]

·                          sulfonamides, 

·                          isoniazid (INH) (Nydrazid, Laniazid)

·                          sulfamethoxazole (Gantanol), 

·                          trimethoprim (Trimpex; Proloprim, Primsol)

·                          nitrofurantoin (Macrodantin; Furadantin; Macrobid), 

·                          fluconazole (Diflucan ) and some other anti-fungals, etc.

Cholesterol lowering drugs such as:

·                          the statins:

o                                         lovastatin (Mevacor, Altocor), 

o                                         pravastatin (Pravachol), 

o                                         atorvastatin (Lipitor),

o                                         fluvastatin (Lescol),

o                                         rosuvastatin (Crestor),

o                                         simvastatin (Zocor), and

·                          niacin

Cardiovascular drugs such as:

·                          amiodarone (Cordarone),

·                          hydralazine (Apresoline) 

·                          quinidine (Quinaglute, Quinidex), etc.

Other drugs

·                          Antidepressant drugs of the tricyclic type

With drug-induced liver enzyme abnormalities, the enzymes usually normalize weeks to months after stopping the medications.