Laboratory MedNews

Clinical chemistry is defined in layman’s language as the study of the substance in biological fluids most specifically blood,  the methods and principles of determination, the intrinsic and extrinsic precautions, the normal levels and the clinical significance of abnormal values.

It belongs to the same discipline as clinical toxicology, endocrinology, physical chemistry, qualitative chemistry, quantitative chemistry, organic chemistry, inorganic chemistry, general chemistry, and biochemistry.

Clinical chemistry is tackled in three general topics for medical technology students. Clinical chemistry 1 is Pure Blood Chemistry including the following topics: Introduction to clinical chemistry, laboratory math, quality assurance, specimen collection, carbohydrates, lipids, proteins, renal functions tests, and liver function tests.

Clinical chemistry 2 is Special Chemistry, which includes automation, blood gas analysis (BGA), electrolytes and enzymology.  Blood gas analysis is very important in the maintenance of the acidity and alkalinity of blood.  The determination has special precautions like an anaerobic collection and the use of dry heparin as an anticoagulant. Electrolytes, on the other hand, are very important substances too that the body has to maintain concentrations of. An elevation and decrease of the concentration levels indicates an existing pathologic condition.

Clinical chemistry 3 includes Toxicology, endocrinology, and drug testing.  Toxicology is the section that deals with toxins that affect man. These include heavy metals, over-dosage of prescribed drugs, prohibited drugs, strong acids, strong bases and many more.  Drug testing is specifically for drugs of abuse and illegal drugs. For endocrinology, different hormones in the body are studied and are utilized to help in the diagnosis of diseases.

Universities and colleges may differ a little bit from the topics included with each phase of clinical chemistry. What is important is that all of the topics are included and are discussed.

Clinical chemistry also is one very important section in the clinical laboratory because it is here where the concentrations of various substances are determined.  Normal levels of each substance have been established and this is the basis for interpreting whether the results or concentrations of the unknown substance is normal or not. It the values fall below or above the normal levels, and then there is an existing pathologic condition or disease in the person. That is why it is very important that all procedures starting from patient identification, to specimen collection, to assaying, to reporting and recording should be reliable.  Correct diagnosis of the patients’ condition is very important to facilitate successful therapy.

In order for the body to function normally, the maintenance of the acidity and alkalinity of the body is vital. The normal pH of blood is 7.35 to 7.45 with an average of 7.4. This slightly alkaline blood pH must be maintained to avoid detrimental effects like comma and evident death. How the body maintains its acidity and alkalinity is a complex process. Presented here is a simple outline regarding the complex process.

Organs involved

The organs involved in the maintenance of blood pH are the lungs and the kidneys. The lungs exhale carbon dioxide to help with pH control while the kidneys excrete hydrogen ions and bicarbonates according to the needs of the body.

Substances involved

Carbon dioxide and hydrogen are considered acidic substances they are excreted more when the body is too acidic. Bicarbonate is considered an alkaline substance so it is excreted more when the body is too alkaline.

Processes that occur

How the body maintains its acidity and alkalinity is based on the processes that occur in the kidneys and the lungs.

Hyperventilation

When the kidneys are dysfunctional and could not respond to the imbalance in blood pH, the lungs will respond. People hyperventilate to bring out more carbon dioxide, an acidic substance, thereby decreasing the acidity of the blood. When there is alkalosis, hypoventilation occurs to retain more carbon dioxide hence, making the blood more acidic.

Bicarbonate excretion by the kidneys

If the lungs are dysfunctional, the kidneys will respond by increasing or decreasing the excretion of bicarbonate and hydrogen ions. When the body is acidotic or has the condition acidosis, the kidneys will excrete more hydrogen ions and retain more bicarbonate to return the blood pH to normal. When the body is alkalotic, the kidneys will increase the excretion of bicarbonate and decrease the excretion of hydrogen ions. Through these processes, the blood pH is maintained.

Acid-base buffer system in the body

The formation of carbonic acid and bicarbonate is reversible so when the body needs more alkalinity, bicarbonate is formed. If the body needs more acidity, carbonic acid is formed.

Homeostasis is maintained through these processes and normal blood pH is restored. In cases where both the lungs and the kidneys are dysfunctional then medical intervention is needed and appropriate medication or management is given to the patient.

Knowing how the body maintains its acidity and alkalinity is good because you will understand why at times you hyperventilate even when you do not want to.

In the laboratory, it is crucial that the clinical laboratory scientist performs the tests reliably, because the doctor bases his diagnosis on these laboratory results. Any source of error therefore is eliminated to ensure that all results are accurate. One source of unreliable results is hemolysis.   Hemolysis is the destruction or rupture of red blood cells (RBCs) causing the release of hemoglobin.   An indication of hemolysis is a pink colored serum or plasma.

Here are pointers to avoid hemolysis in blood samples.

1. Do not use wet materials because water is a hypotonic solution that causes lysis of RBCs.

2. Do not squirt blood directly into the test tube. The rapid flow may cause hemolysis. Allow the blood instead to ooze at the sides of the tube.

3. Remove the needle before transferring the blood to appropriate containers, the small opening of the needle may cause hemolysis.

4. Do not centrifuge blood if it still has not clotted properly.

5. Do not rim or ring the blood several times. This is one major source of hemolysis.

6. Do not freeze whole blood right after collection.

7. Do not vigorously shake whole blood, to avoid hemolysis in blood samples.

8. Do not expose the whole blood specimen to excessively low and hot temperatures.

9. Do not prolong tourniquet application more than necessary.

10.  Transfer the serum immediately to a different container to reduce the propensity for hemolysis.

11.  Do not pull the plunger too quickly. If the bore of the needle is small, it may cause hemolysis

12.   Allow the site to dry first after sterilization.  The alcohol still present in the area may come in contact with your sample and may produce hemolysis.

13.  There should be a proper angle of the needle to the vein to avoid transfixation, which may cause hemolysis.

14.  Any application of mechanical trauma or pressure on the blood sample will cause hemolysis, whether during collection, processing, or transportation.

Avoid hemolysis in blood samples at all cost, as this would produce unreliable results.  Unreliable results would lead to misdiagnosis. Misdiagnosis by the doctor because of your inaccurate results would endanger the life of the patient.  Remember these pointers on how to avoid hemolysis in blood samples and feel confident and secure that you are giving out your best service to patients.  Consider each patient as an important individual who deserves to  receive reliable results.

The diasys spectrophotometer is a brand of spectrophotometer that you can operate manually or semi-manually.  Just like any other spectrophotometer, it operates using the Beer-Lambert’s Law in which the amount of light absorbed is directly proportional to the concentration of the solution. Hence, the more colored a solution is the more concentrated it is, and the less colored a solution is, the less concentrated it is.

Steps

Step 1

Warm up the Diasys spectrophotometer for 10-15 minutes.

Step 2

Code in the number of the test using a standard list. Each substance has an assigned code.  You can modify this number if you want to.

Step 3

Enter the wavelength range and leave the second wavelength prompt blank.

Step 4

Key in the following:  if there are no choices, just type the information in the blanks provided.

1. sipping volume if you are to use the sipping method
2. Temperature for test
3. Units to use
4. Time of incubation
5. Intervals between readings
6. The standard value
7. choice of display values whether absorbance of concentration values
8. highest and lower limits of the substance

Step 5

The Diasys spectrophotometer will prompt you to aspirate water.  Make use of distilled water.

Step 6

The Diasys spectrophotometer will prompt you to read your sample/s.  The machine will blip after every reading.   You could use the cuvette for cell well readings.

Step 7

Record your readings. If they are in absorbance, then you have to compute for the unknown concentration. If they are in concentrations, then you should record and report them accurately.  You can program the machine for automatic printed results also.

Step 8

Terminate your procedure by cleaning the Diasys spectrophotometer of any dust, liquid or dirt. Remove all materials from the machine.  Cover properly and unplug.

Warnings:

1. Warm the Diasys spectrophotometer properly to stabilize it and allow reliable readings.
2. If you decide to use a cuvette, wipe it with soft tissue paper or cloth to prevent smudges and dirt in interfering with the readings.
3. When washing your cuvettes, do not brush them, as scratches would reflect light, making the readings inaccurate.
4. During the readings, remove the solution from the sipping tube as soon as you hear the blip, so air could be aspirated, preventing contamination through the overflowing of one unknown solution to another.
5. Key in the correct information needed to obtain accurate results.
6. Record your results immediately.

You should keep the Diasys spectrophotometer in tiptop shape by protecting it from dirt and contamination.  It should also be calibrated every year.

Fictitious beliefs and half-truths should be categorized for  diabetes mellitus (DM), because the condition precipitates several serious illnesses that could cause death. People should become aware of these myths and classify them from the facts.

Here are some common myths about diabetes mellitus that the public should know about:
1. All diabetic patients are obese and over weight.

Not all persons with diabetes are fat. Persons with type I diabetes mellitus are usually thin, while type II DM (Diabetes Mellitus) persons are usually obese. The weight and size of a person does not indicate whether he/she has DM or not. Only a blood test could determine whether a person is diabetic or not. An FBS (Fasting Blood Sugar), RBS (Random Blood Sugar) or 2-HPPT (Two Hour Post Prandial Test) should be performed in the clinical laboratory to determine this.

2. Diabetes is curable.

Diabetes is a lifetime condition. Once you have it, it will stay. Diabetes can only be properly managed and controlled. This is because uncontrolled DM can cause irreparable damage to all of your organs, your eyes (retinopathy), your kidneys (nephropathy), and the central nervous system (neuropathy). , so when your blood glucose levels go back to normal, do not assume that you are “cured” already, and start going back to your eating binges.

Your observance of proper diet and exercise should be a lifetime process. Although the DM genes may skip a generation or two, it will always appear down line in your family’s lineage.

Scientists are now trying to find a way to alter the genetic composition of a DM person so that the genes would not be passed on from one generation to another. If this happens in your lifetime, then you are lucky!

3. Diabetes is only caused by the lack or absence of insulin.

This is not always the case. Although people know that DM is the insufficiency and lack of insulin and is not acquired from eating too much sugar, people should also be aware that one of the symptoms of DM, which is hyperglycemia (elevation of blood sugar), could be the result of the increase secretion of the hormones glucagon in the alpha cells of the Islets of Langerhans and adrenaline in the adrenal medulla. These secretions can be triggered by caffeine, stress, and emergency situations.

4. Minor wounds would not pose a potential danger for a diabetic person.

A sad fact is that even a small pedicure or manicure wound could cause a gangrenous feet to be amputated. Any wound no matter how small it is should never

be taken for granted. Diabetic patients usually have wounds that have difficulty healing, so they are more prone to infection.

Infection often comes from pathogenic microorganisms like Clostridium perfringens which causes gangrene (necrotization or death of body tissue.) When the tissues or cells die in one part, then it has to be amputated or this will infect all of the parts of the body and would cause inevitable death. If the gangrenous part is amputated, then the rest of the body would be spared.

5. Only sugar and sugar containing foods should be minimized in a diabetic patient’s diet.

This is a half-truth. People should be aware that the most predominant carbohydrate in the bloodstream is glucose. Glucose is a simple sugar generally called a monosaccharide. Glucose comes, not only from sugar, but from a variety of bland foodstuffs like bread, rice (yes, rice!) pasta (even plain pasta), potatoes and many unsweetened foods. This is because glucose is the end product of the metabolism of any carbohydrate in which rice and the rest are included.

Excessive fat intake also could exacerbate the condition. The dietary fat could be stored as triglyceride and would add to the obesity of the person. It should be remembered that losing weight is one good management control for DM patients. So when the doctor tells you to limit your rice and fat intake, do so.
6. All sweet fruits should be avoided as they contain high levels of sugar.

Not all fruits have high sugar levels. Apple, grapefruit, strawberries, papayas, watermelons are examples of fruits good for diabetic persons. These however should be taken in fresh and not in the form of juices or shakes as these preparations have high artificial sugar content. It should be noted that there is also high fiber content with these fruits and are therefore healthy for the body.
Old myths may be proven false eventually but new myths are generated in return. People should have wisdom in distinguishing the two through proper information and education. Do not believe everything you hear through the grapevine. Take time to read good reference materials and be informed!