About Lab Tests

The Haematology discipline also studies how efficiently blood clots. Haemophiliacs for example have a bleeding tendency and as such their condition is studied with these tests. Patients who take drugs to “thin” their blood and prevent it from clotting too quickly require regular  PT (Prothrombin Time) and INR (International Normalized Ratio) tests to monitor such drugs.

Other haematology investigations include mono tests to help diagnose the presence of infectious mononucleosis and investigations that detect the presence of abnormal haemoglobins by molecular structure e.g.  Hb Electrophoresis.

There are many different kinds of chemistry test which detect analytes quantitatively.  Most of the routine chemistry tests are carried out on automated analyzers.  Some common examples are

• Glucose – measured for the diagnosis and monitoring of Diabetes Mellitus
• BUN and Creatinine – tests of kidney function
• Calcium and Phosphorus – tests used to evaluate Calcium physiology and to assist in the diagnosis of the cause of osteoporosis
• Sodium, Potassium, Chloride (electrolytes) – these are salt balance tests which are important for people with kidney disease and in people taking diuretics or in management of dehydration and in alkalosis
• Bilirubin, ALP, AST, ALT, GGT –  tests of liver function
• Total Protein and Albumin – these provide information about liver function, kidney disease, infection, nutrition, and certain disorders of the antibody producing cells.

Immunology tests assess the body’s immune system. .  There are a variety of tests that help detect autoimmune disease and assist in clarifying disorders of the immune system eg ANF, Anti DNA, LE Cells etc.  When the immune system “over-reacts”, the body regards its own tissue as a “foreign substance” and begins to inflict damage on itself e.g Lupus Erythematosus; when the immune system is immunocompromised or “under-reacts” the patient is unable to ward off infections as a normal response eg in HIV patients.

These tests evaluate levels of various hormones present in blood, the most common ones being

• Thyroid Function Tests (e.g. T3, T4 TSH) – these are used to detect disorders of the thyroid gland and assist with treating thyroid disease
• Testosterone – the “male” hormone low levels in men or elevated levels in women result in clinical problems
• LH and FSH – these hormones which control the menstrual cycle in women and the production of testosterone and sperm in men are used to assess fertility

The Microbiology lab helps to determine what is causing an infection and how best to treat it. Testing employs swabs, blood, urine, or faeces. Swabs are sterile sticks with cotton wrapped around one end. The infected area is swabbed with the cotton tip (like a sore throat or a wound) in order to “pick up” some of the bacteria that are causing the infection. Swabs or other materials are smeared on the surface of a small plate of agar (a nutrient rich gelatine-like material) and placed overnight in an incubator that is maintained at body temperature. After timed incubation, the plates are removed and examined for the presence of bacterial growth. Using a microscope, special stains and chemical tests, technologists can determine the type of bacteria that is present. Further testing then determines which antibiotics will inhibit or eliminate the bacteria.

Fungal studies as well as the presence of parasites in faeces can also be detected in this part of the lab.

There are two types of drug testing

• Drug screening – used to detect illicit drug administration. These tests are carried out on persons receiving drug treatment with Methadone, on those who have “overdosed”, and for legal purposes.
• Therapeutic Drug Monitoring (TDM) is carried out to help control the dose of prescription drugs.

This is a common observation and evaluation consisting of a series of chemical tests. These are conducted using a plastic strip with chemical pads/testing sites (dipstick) which is soaked in the sample and then “read” by visual appearance or using a machine. The tests help to detect diabetes, liver disease, diseases of the kidney and bladder and some blood disorders and infections.  The urine is also examined under a microscope to confirm findings such as RBCs, WBCs, casts, yeasts and even parasites