INVESTIGATION OF DISEASE
History taking and clinical examination by the doctor provides a tentative diagnosis of disease. Investigations are of two types: laboratory testing and X-ray scanning.
Investigations by laboratory testing of body secretions can reveal whether the organ functions are affected and to what extent. X-ray and scanning by CT scan or MRI technology tells us of structural abnormalities of the organ, caused by disease.
Blood, urine and stools are routinely examined in the pathology laboratory.
X-Rays are cheap and serve to screen the body tissues before performing time consuming and expensive CT or MRI scans. While CT Scans can cause significant radiation exposure, MRI’s rely on magnetism and do not cause radiation exposure, being enclosed within the funeral casket of a scanner with loud clanging noises can often unnerve the patient and make him claustrophobic.
The BASIC BLOOD TEST is made of
BLOOD CELL COUNT: is made of Red Blood Cell (RBC), White Blood cell (WBC) and Platelet count per mm3 of blood. RBC count is in millions, WBC in thousands and Platelets in Lakhs. When Haemoglobin (or Red Blood Cells) levels fall, it is called Anaemia and makes a person pale and tired. WBC count rises in Bacterial infection & falls in viral infections, malaria and typhoid. Platelet count falls in serious haemorrhagic fevers like Dengue. WBCs rise in phenomenal numbers in Leukaemia.
HAEMOGLOBIN & RBC COLOR: Fall in Haemoglobin levels produces Anaemia. Anaemia can be caused by Nutritional Deficiency or Blood loss. Dietary deficiency of Iron causes RBCs to become smaller, less coloured while Vitamin B12 or Folic Acid deficiency causes RBCs to become bigger and retain their colour.
ESR -ERYTHROCYTE SEDIMENTATION RATE: This nonspecific Test is about the rate of fall of cells in stagnant blood. ESR is grossly raised in autoimmune disease, TB and Cancers.
LIVER FUNCTION TEST: The destruction of RBC’s after its lifespan of 21 days results in yellow pigment Bilirubin which is metabolised by the Liver. Liver disease impedes bilirubin metabolism causing bilirubin levels to rise in blood and cause a yellowish tint of the skin, nails and eyes. The Lab test shows a rise of Bilirubin levels in the blood. Destruction of the liver cells releases enzymes called SGPT and SGOT into blood.
KIDNEY FUNCTION TEST: Kidney excretes urea. In Kidney failure urea excretion is reduced and therefore the blood level of Urea or (BUN – Blood Urea Nitrogen) rises.
URINE TEST: Urine shows pus cells (WBCs) in Urinary Tract Infection. Urine shows presence of oxalate crystals in Renal Stone disease.
STOOL TEST: Stools show Amoeba or Worms or Worm eggs. This can help diagnose abdominal pain or diarrhoea.