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Relationship between biochemical tests and disease

What is a biochemical tests?

Biochemical test is a laboratory test that is conducted in a hospital or health clinic to find out the individual’s status health. These biochemical test results are used by medical practitioners to perform diagnosis, prognosis and to monitor the disease.

What types of tests are involved?

Among the routine tests that carried out included:

  • Kidney function test (Renal Profile Test)
  • Lipid Profile test
  • Glucose test
  • Liver function tests

Kidney Function Test (Renal Profile Test)

The kidneys have important roles in regulating the electrolytes balance (eg : sodium and potassium) and acid-base homeostasis in the human body. The kidneys also monitor the body’s blood pressure and involved in excretion of waste products through urine and reabsorbing some substance that needed by the body. Kidneys also are able to filter the metabolic products such as urea and creatinine.

The parameters tested in kidney function tests are sodium, potassium, urea and creatinine. Sodium is the major electrolyte in water regulation in the body. No special preparation is required and the patient’s blood can be taken at any time to run the test. Normal serum sodium levels are between 135-145 mmol/L. Hypernatremia is defined by an elevated sodium level in the blood while hyponatremia is a condition that occurs when the level of sodium less than 135 mmol/L.

Potassium helps nerves and muscles communicate. It also helps move nutrients into cells and waste products out of cells. The normal potassium level in the blood is 3.3-5.3 mmol/L. Hyperkalemia is an excessive level of potassium in the bloodstream while hypokalaemia is a condition that occurs when the level of potassium is abnormally low.

Urea and creatinine have been used by clinician as a marker of renal function. Urea is a waste product formed from the breakdown of proteins while creatinine is a specific product for muscle metabolism. Increase concentration of urea in the blood may indicate acute and chronic renal dysfunction meanwhile increase creatinine level may indicate chronic renal dysfunction. A normal range for urea is 2.5 – 8.0 mmol/L while for creatinine is 62-106 umol/L (men) and 44-80 umol/L (women).

Lipid Profile Test

Lipid Profile test include:

  • Triglycerides
  • Cholesterol
  • LDL (low-density lipoprotein cholesterol)
  • HHDL (high-density lipoprotein cholesterol)

Triglycerides

Triglycerides are a type of fat found in the blood that the body uses for energy. Mostly, triglycerides are made in the liver and some are come from the diet. High triglyceride levels are associated with coronary heart disease.

Many factors affect blood triglyceride levels including less physical activity, smoking, excessive alcohol consumption, intake of high carbohydrate diet, medication and some types of diseases and genetic disorders. The normal range for triglycerides is between 0.5 – 1.8

Cholesterol

Cholesterol is a type of lipid that is found throughout the body. It is produced by the liver and can be get from certain foods. Cholesterol is required in the body’s metabolic processes for the formation of new cells and synthesis hormones. However, excess cholesterol will form plaque between layers of artery walls, making it harder for heart to circulate blood. Thus, a clot blocks an artery will causes a stroke and heart attack. Hypercholesterolemia is a condition that occurs when the cholesterol level is high. A normal range for cholesterol is between 3.9 – 5.5 mmol / l.

Low density lipoprotein (LDL)

Low density lipoprotein (LDL) contains mostly 75% of cholesterol and a smaller proportion of protein. LDL is responsible for delivering cholesterol to the parts of your body that need it. Excess LDL, however, causes a buildup of cholesterol in the walls of your arteries, contributing to the development of atherosclerosis. It is also known as a bad cholesterol. The normal range for LDL is <3.3 mmol/L.

High-density lipoprotein (HDL)

High-density lipoprotein (HDL) is known as a good cholesterol. The job of HDL is to remove excess cholesterol from the cells and the walls of the arteries and then transport the cholesterol back to the liver for disposal. It may actually slow or even reverse the development of atherosclerosis. The normal range for HDL is between 1.0 – 2.2 mmol/L.

Glucose test

A blood glucose test measures the amount of a sugar called glucose in a sample of blood and this test may also be used to screen a person for diabetes. There are several types of glucose test included:

  • Fasting Blood Sugar (FBS). FBS are measured by taking a blood test after a period of fasting, usually of 8 hours without food. The normal range is between 3.0 – 5.4 mmol/L.
  • Random Blood Sugar (RBS). A blood sample will be taken at a random time to get a picture of the glucose concentration in the bloodstream. High random blood sugar will shows that a person may has diabetes. But it is not a confirmatory test to diagnose a person with diabetes or not. The normal range is between 3.0 – 7.7 mmol/L.
  • 2- Hour Postprandial Glucose (2HPP). This test measures blood glucose exactly 2 hours after eating a meal timed from the start of the meal. This test is done to see the effectiveness of the pancreas produces insulin to control the sugar.
  • Oral Glucose Tolerance Test (OGTT). The test is used to determine whether the body has difficulty metabolizing intake of sugar/carbohydrate. It is a screening test for the diagnosis of diabetes among pregnant women. The patient is asked to take a glucose drink (75g glucose in 250-300ml of water) and their blood glucose level is measured before and 2 hour after the sugary drink is taken.

Uncontrolled diabetes can lead to complications of eyes, kidneys and heart.

Liver Function Tests (LFT)

Liver function tests (LFT) measure the levels of certain enzymes and proteins in the blood. This test is used to help diagnose and monitor liver disease or damage.

LFT also used to assess the general state of the liver and it can also indicate other diseases, such as malnutrition or bone disease.

Liver function tests are performed:

  • To detect infection of the liver, such as hepatitis.
  • To monitor the development of diseases such as viral hepatitis or alcohol and the effectiveness of the treatment.
  • To measure the level of a disease, especially cirrhosis.
  • To monitor the side effects of the certain drugs.

An abnormal LFT result indicates a problem with the liver and may help to identify the cause. Tests that commonly run under liver function profiles are:

  1. Alanine transaminase (ALT)

    Large amounts of ALT are found in liver cells. ALT is an enzyme that helps to process proteins. When the liver is injured or inflamed (as in hepatitis), the blood level of ALT usually rises. The normal range of values for ALT is between 0-41U/L.

  2. Aspartate transaminase (AST)

    AST is an enzyme that plays a role in alanine and amino acid metabolism. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage. The normal range of values for AST is between 10-35U/L.

  3. Alkaline Phosphatase (ALP)

    Alkaline phosphatase (ALP) is a enzyme found in all body tissues especially in the liver, bile ducts and bone. ALP levels are higher than normal levels indicate the occurrence of cholestasis. The normal range for ALP is between 35-104 U/L.

  4. Albumin and Total Protein

    Albumin and total protein is made mainly in the liver. It helps our body as carrier protein, fight against infection and other function. Lower than normal levels may indicate liver damage or disease. The normal range for albumin is between 35-52 g/L for adults, while the normal range for total Protein is 66-87 g/L.

  5. Total Bilirubin

    Bilirubin is a brownish yellow substance found in bile. It is produced when the liver breaks down old red blood cells. Bilirubin is then removed from the body through the stool (feces) and gives stool its normal color. Higher than normal levels of bilirubin may indicate different types of liver problems. Occasionally, higher bilirubin levels may indicate an increased rate of destruction of red blood cells. Increased levels of bilirubin can also be viewed with the naked eye, namely skin and eyes turn yellow. The normal range is between 0.0 – 17.1 umol/L.

 

Last Reviewed : 26 February 2015
Writer : Asmashah bt. Arshad
Translator : Annurin Ainulhidayah bt. Adenan
Accreditor : Rusli bin Ibrahim