Dayyal Dg.

Dayyal Dg.

Clinical laboratory professional specialized to external quality assessment (proficiency testing) schemes for Laboratory medicine and clinical pathology. Author/Writer/Blogger

Wednesday, 12 December 2018 22:46

CLASSIFICATION OF DIABETES MELLITUS

Diabetes mellitus (DM) is a metabolic group of disorders characterized by persistent hyperglycemia due to deficiency and/or diminished effectiveness of insulin. There are derangements of carbohydrate, protein, and fat metabolism due to failure of insulin action on target cells.

Saturday, 24 November 2018 19:47

Detection of Fake or Adulterate Urine Sample

Detection of a fake or adulterated urine sample is necessary before going to the further process of urine testing in the laboratory. Urine adulteration causes false-positive and false-negative results. However, most attempts of a fake or adulteration in a urine sample can be detected either by a trained collection site personnel or by a laboratory technician during the testing process. Coordination and cooperation between the collection site and the testing laboratory provide effective and reliable test results. There are some methods by which fake or adulterated urine can easily identify.

Electrocardiogram (ECG / EKG) test is important for the diagnosis of myocardial infarction. ECG reading is obtained rapidly from ECG machine. ECG scan is useful for diagnosis, prognosis, and monitoring of myocardial infarction.

Thursday, 01 November 2018 05:32

Examination of Peritoneal Fluid

The peritoneal cavity is a potential space in the abdomen lined by mesothelial cells and normally containing about 30-50 ml of serous fluid. The fluid is an ultrafiltrate of plasma and its formation is dependent upon hydrostatic pressure, plasma oncotic pressure, and capillary permeability.

Monday, 20 August 2018 12:10

Exercise Tolerance Test (ETT)

The exercise tolerance test (ETT) is also known as an exercise electrocardiogram (ECG). This test is done to assess the severity of coronary heart disease. In such condition, the blood vessels are narrowed due to the blockage causing irritation for free-flowing blood supply to the heart. Exercise tolerance test (ETT) assess the response of the heart to raised workload and demand of blood. This is obtained by recording the ECG whilst the patient start walking on a treadmill machine.

Once the patient starts walking on the treadmill, heart rate, blood pressure, general condition and ECG will be monitored continuously. After every 3 minutes, the speed and incline of the treadmill will be increased. The patient will be encouraged to exercise for as long as he/she can and the test will be continued until the patient reaches to the desired heart rate and/or cannot exercise anymore (usually 10 to 15 minutes). After the test, the patient will be asked to rest while his/her ECG and blood pressure are recorded and until his/her recordings reach the normal baseline heart rate. All the recordings will be analyzed by a cardiologist (a doctor with special training to treat heart-related diseases).

What is an electrocardiogram (ECG)?

An electrocardiogram (ECG) test is done by an ECG machine. It records the electrical activity of the heart. The heart produces micro electrical impulses which spread through the heart muscle to make the heart contract. The micro electrical impulses are detected by an ECG machine. The ECG machine amplifies the micro electrical impulses that occur at each heartbeat and records them on to a paper or computer.

An ECG recording is harmless since it records the electrical impulses coming from your body and it does not put any electricity into your body.

What is an exercise tolerance test (ETT)?

An exercise tolerance test (ETT) records the electrical impulses of your heart whilst you exercise. This test is very useful for a patient experiencing chest pain when they exert themselves. This test is also very useful for the detection of rhythm abnormalities.

Some decades ago this was the routine test of choice to investigate a patient for the presence of narrowing of the arteries to the heart. Nowadays it is common for scans of the heart to be done rather than an ETT. The scans that can be done for the heart include:

  • Computerised tomography (CT) coronary scan/CT coronary angiography
  • Cardiac magnetic resonance imaging (MRI) scan of the heart
  • Myocardial perfusion scan

How is an exercise tolerance test (ETT) done?

Small electrodes are stuck on to the patient's chest. Wires from the electrodes are connected to the ECG machine. The patient is asked to walk on a treadmill and the heart rate, blood pressure, general condition and ECG is monitored continuously. After every 3 minutes, the speed and incline of the treadmill are increased. The patient is encouraged to exercise for as long as he/she can and the test is continued until the patient reaches to the desired heart rate and/or cannot exercise anymore (usually 10 to 15 minutes). After the test, the patient is asked to rest while his/her ECG and blood pressure are recorded and until his/her recordings reach the normal baseline heart rate. All the records are analyzed by a cardiologist. The whole process ends in 15-20 minutes.

Are there any risks when doing an exercise tolerance test (ETT)?

An exercise tolerance test (ETT), normally do not cause any complications since, in this procedure, micro electrical pulses are recorded produced by the heart contraction. For this purpose, ECG machine is used which does not input electricity into your body.

If you do not have coronary heart disease (CHD) then complications are rare. However, serious complications occur in a small number of people who have coronary heart disease and there are reports of, very rarely, some people who have died during an ETT.

WARTS

A wart is a viral infection of the surface layers of the skin. The incubation period varies from a few weeks to several months. Warts can be spread by direct or indirect contact with a wart to damaged skin.

CORNS

A corn is a small, hardened area of skin which often looks yellow compared to the surrounding skin. It is typically round or corn-shaped, pointing down into the skin. Corns most often form on the feet and sometimes on the hands and are caused by constant or repeated friction or pressure.

CALLUSES

A callus is rough, thickened skin spread over a wide area. Like a corn, it caused by constant or repeated friction or pressure, but unlike corns, calluses are flat and have normal skin markings.

Friday, 10 August 2018 19:15

Examination of Cerebrospinal Fluid (CSF)

It is a clear, colorless fluid formed in the ventricles of the brain mainly by choroid plexus (an interlaced structure or meshwork of tiny small blood vessels in the lateral third and fourth ventricles). It is mainly an ultrafiltrate of plasma.

Sunday, 05 August 2018 08:51

Stool Examination for Ova and Parasites

Waste products excreted from the digestive tract are composed of water (up to 75%), indigestible residue, undigested food, food which is digested but not absorbed, bile, epithelial cells, secretions from the digestive tract, inorganic material, and bacteria. The normal amount of feces in an adult is 100-200 grams per day. Examination of feces is helpful in the investigation of diseases of the gastrointestinal tract.

Saturday, 04 August 2018 08:05

Bilirubin: Conjugated (Direct Bilirubin)

Collection of sample

This test is performed with the patient's serum. There is no restriction for a fasting sample. The test can be done by a random blood sample the patient.

About 3 to 5 ml of blood is collected in a plain test tube, and blood is allowed to clot to get clear serum. In infants, the sample may be collected from the heel. The blood sample is centrifuged for 5 to 10 minutes and the serum is separated for the test.

The patient's serum is stable at 4° C for 3 days and protects it from the light.

Note: Bilirubin is photo-sensitive (photo-oxidized) so keep the sample in dark place otherwise false-negative results may obtain.

Precautions

  • Avoid sample from hemolysis
  • Do not expose the sample to light. Exposure of sample to light may decrease the value.
  • If there is a delay in performing the test then keep the sample in dark and refrigerate it.
  • Avoid shaking of the test tube as it may lead to an inaccurate result.

Pathophysiology

  • Serum bilirubin is a very useful test to evaluate liver functions. Raised level of bilirubin can be seen in the hepatic and post-hepatic type of jaundice.
  • Clinically jaundice appears when the level of bilirubin is more than 2 mg/dl.
  • Direct (or conjugated) bilirubin: It is water-soluble and dissolves in water and is synthesized in the liver form indirect bilirubin.

Normal Values

  • Total bilirubin 0.3 to1.0 mg/dL or 5.1 to 17.0 mmol/L
  • Direct bilirubin 0.1 to 0.3 mg/dL or 1.0 to 5.1 mmol/L
  • Indirect bilirubin 0.2–0.7 mg/dL

Raised level of direct bilirubin is seen in

  • Gallbladder tumors
  • Gallstones
  • Dubin-Johnson syndrome
  • Rotor syndrome
  • Obstruction of extrahepatic ducts or inflammatory scarring
  • Can be resolved by the surgery
  • Drugs may cause cholestasis

Why is this test performed?

This test is performed for the diagnosis and differentiation of jaundice. This test is also done in a patient with hemolytic anemia in adult and newborn. This test is very useful to evaluate liver functions and for the follow-up of a patient with treatment.

Collection of sample

This test is performed with the patient's serum. There is no restriction for a fasting sample. The test can be done by a random blood sample the patient.

About 3 to 5 ml of blood is collected in a plain test tube, and blood is allowed to clot to get clear serum. In infants, the sample may be collected from the heel.

The blood sample is centrifuged for 5 to 10 minutes and the serum is separated for the test. The patient's serum is stable at 4° C for 3 days and protects it from the light.

Precautions

  • Avoid sample from hemolysis
  • Do not expose the sample to light. Exposure of sample to light may decrease the value.
  • If there is a delay in performing the test then keep the sample in dark and refrigerate it.
  • Avoid shaking of the test tube as it may lead to an inaccurate result.

Pathophysiology

  1. This is the end product of hemoglobin metabolism.
  2. From the breakdown of RBC, hemoglobin is released in form of Heme and Globin. Heme is further metabolized to Biliverdin and this is transformed into bilirubin.
  3. The raised level of bilirubin is the indicator of liver dysfunction.
  4. Bilirubin is a component of bile which is transported from the liver and stored in the gallbladder and from that organ, it is it is delivered to the intestine.
  5. Bile formed in the liver. It is made up of bilirubin, bicarbonate (HCO3), phospholipids, cholesterol, bile salts, and water.
  6. Further metabolism of bilirubin takes place in the intestine.
  7. Most of it is metabolized in the intestine and discharged in the feces.
  8. An increased level of bilirubin causes the yellow color of the skin and jaundice (conjunctiva).
  9. The bilirubin which is not conjugated to the liver, attach to albumin (carrying protein) is called Indirect bilirubin.
  10. The bilirubin conjugate with the glucuronic acid. This process takes place in the liver and gives rise to direct or conjugated bilirubin. Now conjugated bilirubin is no more bound to protein.
  11. Jaundice occurs when the bilirubin level is above 2.5 mg/dl.
  12. When the bilirubin level exceeds 15 mg/dl then the treatment is immediately started to avoid the brain damage.
  13. While physiologic jaundice appears after 3 to 4 days and subsidies itself.
  14. In the newborn, when the liver can not conjugate bilirubin and if the level increases then this indirect bilirubin can cross the blood-brain barrier which may lead to toxic injury to the brain and called Kernicterus.

Types of jaundice

Types of jaundice are defined as follows:

  • Pre-hepatic jaundice: The etiology is before the liver like excessive hemolysis of RBC.
  • Hepatic jaundice: Dysfunction of the liver caused by hepatic diseases e.g. hepatitis.
  • Post-hepatic jaundice: The cause is after the liver like cancer, gallstone, etc. These are the obstructive type of jaundice.
Table 1178.1 Different type of Jaundice and their causes
Type of Jaundice Causes Pathophysiology
Conjugated hyperbilirubinemia Drugs like cyclosporine and estrogen
Dubin-Johnson syndrome
Pregnancy
There is a defect in the transmembrane secretion of conjugated bilirubin into the canaliculus. This is also called hepatocellular jaundice.
  Mechanical obstruction by stones or strictures, tumors, and primary biliary cirrhosis There is a defect in the flow of conjugated bilirubin through canaliculi and bile ducts. Called cholestatic jaundice.
  Sepsis Like above
Unconjugated hyperbilirubinemia Drugs like Rifampicin and Gilbert syndrome There is a defect in the uptake of unconjugated bilirubin into hepatocytes
  Right heart failure and Cirrhosis There is a defect in the delivery of unconjugated bilirubin to liver
  Extravascular hemolysis Heme is converted to unconjugated bilirubin
  Crigler-Najjar syndrome and Hypothyroidism There is a defect in the conjugation of bilirubin in the hepatocytes
Table showing the Different type of Jaundice and their causes

Calculation of total, direct and indirect bilirubin

Total bilirubin is calculated as follows:

Total bilirubin = Direct bilirubin + Indirect bilirubin

Direct bilirubin is calculated as follows:

Direct bilirubin = Total bilirubin – Indirect bilirubin

Indirect bilirubin is calculated as follows:

Indirect bilirubin = Total bilirubin – Direct bilirubin

Normal Values

  • Total bilirubin 0.3 to 1.0 mg/dL or 5.1 to 17.0 mmol/L
  • Direct bilirubin 0.1 to 0.3 mg/dL or 1.0 to 5.1 mmol/L
  • Indirect bilirubin 0.2 to 0.7 mg/dL or 3.4 to 11.9 mmol/L

Total bilirubin in

  • Umbilical cord blood less than 2 mg/ dl

Normal values of total bilirubin in infants

  • 0 to 1 days less than 6 mg/ dl
  • 0 to 2 days less than 8 mg/ dl
  • 3 to 5 days less than 12 mg/dl
  • after 5 days less than 0.2 to 1.0 mg/ dl

Physiologic jaundice of the newborn

  • This is found in the newborn when the liver is immature and an insufficient amount of conjugating enzymes. This will lead to an increased amount of unconjugated bilirubin.
  • This unconjugated bilirubin can cross the blood-brain barrier and give rise to encephalopathy (Kernicterus).

Bilirubin level more than 15 mg/dl in newborn needs immediate treatment.

  • This is treated by the exchange of blood or light therapy.

Raised Bilirubin level is seen in

  • Diseases that cause liver damage, such as cirrhosis, hepatitis, or mononucleosis.
  • In some infections, such as cholecystitis, and an infected gallbladder.
  • In some inherited diseases, such as Gilbert’s syndrome. Although jaundice may occur in some people with Gilbert’s syndrome, the condition is not harmful.
  • In some diseases that cause blockage of the bile ducts, such as cancer of the pancreas or gallstones.
  • Medicines that may increase the level of bilirubin. This consist of many antibiotics, diazepam (Valium), some types of birth control pills, phenytoin (Dilantin), flurazepam (Dalmane), and indomethacin (Indocin).
  • Rapid destruction of red blood cells in the blood, such as from an allergic reaction to blood received during a transfusion (called a transfusion reaction) or sickle cell disease.

Decreased Bilirubin level is seen in

  • Medicines that may decrease the level of bilirubin. This includes phenobarbital, vitamin C (ascorbic acid), and theophylline.

Bilirubin levels that may require treatment in a full-term, healthy baby

  • 24 hours or younger infant needs to be treated if the level of bilirubin is more than 10 mg/dL or more than 170 mmol/L.
  • 25 to 48 hours infant needs to be treated when the level of bilirubin is more than 15 mg/dL or more than 255 mmol/L.
  • 49 to 72 hours infant needs to be treated when bilirubin level is more than 18 mg/dL or more than 305 mmol/L
  • Older than 72 hours infant need to be treated when the bilirubin level is more than 20 mg/dL or more than 340 mmol/L

Causes of direct hyperbilirubinemia

If the direct bilirubin level is more than 50%.

  1. Gallbladder tumors
  2. Gallstones
  3. Dubin-Johnson syndrome
  4. Rotor syndrome
  5. Obstruction of extrahepatic ducts or inflammatory scarring
  6. Can be resolved by the surgery
  7. Drugs may cause cholestasis

Causes of Indirect hyperbilirubinemia

If the indirect bilirubin level is less than 15 to 20%.

  1. Hepatitis
  2. Increased RBC hemolysis ( Erythroblastosis fetalis)
  3. Sickle cell anemia
  4. Congenital enzyme deficiency
  5. Cirrhosis
  6. Gilbert syndrome
  7. Crigler-Najjar syndrome
  8. Drugs
  9. Transfusion reactions
  10. There is no role of surgery
Page 2 of 18