Aspartate Amino Transferase (SGOT)

Overview

Aspartate Aminotransferase (AST), also known as Serum Glutamic-Oxaloacetic Transaminase (SGOT), is a vital liver enzyme that helps convert food into energy for various body functions. While primarily found in the liver, it is also present in the heart, kidneys, brain, muscles, lungs, and red blood cells.

When cells in these organs are damaged, SGOT leaks into the bloodstream, resulting in elevated serum levels. The test for SGOT is therefore an essential marker in diagnosing liver injury, heart disease, muscle damage, and other organ dysfunctions.

SGOT is often measured alongside Serum Glutamic Pyruvic Transaminase (SGPT) as part of the Liver Function Test (LFT). The AST/ALT (De Ritis) ratio helps differentiate between types of liver diseases. Normally, this ratio is less than 1 (0.7–0.9). A ratio above 1 suggests liver cell injury, while a ratio greater than 2:1 is a classic indicator of alcoholic liver disease.

SGOT testing also aids in monitoring ongoing liver conditions, evaluating treatment response, and detecting complications such as hepatitis, cirrhosis, and myocardial infarction (heart attack).

Symptoms

SGOT itself does not cause symptoms, but elevated enzyme levels indicate underlying organ damage. Symptoms depend on the affected organ system.

Common Symptoms of Elevated SGOT:

1. Liver-Related:
   1. Yellowing of skin or eyes (jaundice)
   2. Dark-colored urine and pale stools. Itchy skin
   3. Abdominal pain or swelling
   4. Fatigue and loss of appetite
2. Heart-Related:
   1. Chest pain and tightness
   2. Shortness of breath
   3. Weakness or dizziness
3. Muscle or Systemic Disorders:
   1. Muscle pain, stiffness, or weakness
   2. Swelling in limbs
   3. Nausea and vomiting

These symptoms often prompt an SGOT test to determine the cause of tissue damage.

Causes

Elevated or decreased SGOT levels can be due to various physiological or pathological conditions.

Causes of Elevated SGOT:

1. Liver Diseases:
   1. Viral hepatitis (acute or chronic)
   2. Alcoholic liver disease, Cirrhosis
   3. Cholangitis and hemochromatosis
   4. Reye’s syndrome and congestive cardiac failure
2. Heart Diseases:
   1. Myocardial infarction (heart attack)
   2. Myocarditis
   3. Pulmonary infarction
3. Other Causes:
   1. Muscle injury or rhabdomyolysis
   2. Hemolytic anemia
   3. Acute pancreatitis
   4. Malnutrition and drug-induced liver damage

Causes of Low SGOT:

1. Severe liver damage or cirrhosis (due to loss of functioning cells)
2. Vitamin B6 (pyridoxine) deficiency
3. Chronic renal failure
4. Extensive muscle disease
5. Hypothyroidism
6. Malnutrition and cachexia
7. Pregnancy (physiological decrease)

Risk Factors

Certain conditions or lifestyle factors increase the risk of abnormal SGOT levels:

1. Excessive Alcohol Consumption: Chronic intake causes fatty liver and alcoholic hepatitis.
2. Hepatitis Virus Exposure: Infections from hepatitis A, B, or C raise SGOT levels.
3. Use of Hepatotoxic Medications: Drugs such as erythromycin, amiodarone, methyldopa, and amoxicillin-clavulanate can elevate SGOT.
4. Obesity and metabolic syndrome increase the risk of non-alcoholic fatty liver disease (NAFLD).
5. Occupational Exposure: Contact with industrial chemicals or solvents damaging the liver.
6. Uncontrolled Diabetes or Hypertension: Contribute to liver and cardiovascular strain.
7. Genetic Liver Disorders: Conditions like hemochromatosis or Wilson’s disease predispose to enzyme elevation.

Prevention

Prevention involves maintaining liver and heart health, avoiding toxic substances, and routine health monitoring.

Testing and Sample Collection:

1. Sample Type: 3.0 mL of blood collected in a plain red-capped tube.
2. Processing: Serum should be separated as early as possible and sent to the lab for testing.
3. Methods Used: Quantitative enzymatic assays such as Reitman-Frankel, Karment’s, King’s, Mohun’s, Spectrophotometric, and UV-Kinetic methods.
4. Reference Range:
   1. Males: 5–40 U/L
   2. Females: 9–32 U/L
   3. Children: 15–60 U/L (varies with age)

Prevention and Health Maintenance:

1. Limit or avoid alcohol consumption.
2. Eat a balanced diet rich in antioxidants and vitamins (especially B6).
3. Exercise regularly to support liver and cardiovascular function.
4. Avoid unnecessary medications and always consult before taking supplements.
5. Vaccinate against hepatitis A and B to reduce liver infection risks.
6. Manage metabolic diseases like diabetes and obesity effectively.
7. Undergo routine liver function tests, especially if on long-term medication or with a history of alcohol use.