Blood Tests

Free T3 (Free Triodothyronine)

FreeT3 is the active thyroid hormone present in serum which regulates metabolism.
Determination of this hormone concentration is important for the diagnostic differentiation of euthroid, hyperthyroid and hypothyroid states.
Free thyroid hormone testing may be ordered along with thyroid antibodies to help diagnose Graves’ disease, an autoimmune disorder that is the most common cause of hyperthyroidism.

Free T4 (Free Thyroxine)

FreeT4 is part of the regulating circuit of the thyroid gland and has an effect on general metabolism. Free T4 is measured together with Free T3 and TSH when thyroid function disorders are suspected.    
Since free T4 is the active form of thyroxine, it is thought by many to be a more accurate reflection of thyroid hormone function. This helps the doctor to determine whether the thyroid hormone feedback system is functioning as it should, and the results of the tests help to distinguish between different causes of hyper- and hypothyroidism.
Thyroid hormone tests may be ordered to help evaluate a patient with an enlarged thyroid gland (a goiter) and to aid in the diagnosis of female infertility. If the doctor suspects that the patient may have an autoimmune-related thyroid condition, thyroid antibodies may also be ordered.
Elevated Free T4 results may indicate an overactive thyroid gland (hyperthyroidism), and low Free T4 results may indicate an underactive thyroid gland (hypothyroidism).

The test results alone are not diagnostic but will prompt the doctor to perform additional testing to investigate the cause of the excess or deficiency. Both decreased and increased thyroid hormone results are associated with a variety of temporary and chronic thyroid conditions.

Back To Top

TSH (Thyroid Stimulating Hormone)

TSH is the central regulating mechanism for the biological action of thyroid hormones.
A high TSH result often means an underactive thyroid gland that is not responding adequately to the stimulation of TSH due to some type of acute or chronic thyroid dysfunction.
TSH testing is used to:

• diagnose a thyroid disorder in a person with symptoms,

• monitor thyroid replacement therapy in people with hypothyroidism
• diagnose and monitor female infertility problems,
• help evaluate the function of the pituitary gland (occasionally), and
• screen adults for thyroid disorders (many NHS labs adopt this policy)

The following table summarizes test results and their potential meaning.

Back To Top

Ferritin 

The ferritin test will determine how much iron your body has stored for future use.

Lipid Profile (TC; HDL; LDL; Triglycerides) (Fasting)

Cholesterol Test (TC; HDL; TC/HDL Ratio) (Non-Fasting)

This group of tests are often ordered together to determine risk of coronary heart disease. The tests that make up a lipid profile are tests that have been shown to be good indicators of whether someone is likely to have a heart attack or stroke caused by blockage of blood vessels (hardening of the arteries).
The lipid profile includes total cholesterol, HDL-cholesterol (often called “good cholesterol”), LDL-cholesterol (often called “bad cholesterol”), and triglycerides. The lipid profile is used to guide healthcare professionals in deciding how a person at risk should be treated. The results of the lipid profile are considered along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Patients must provide a fasting blood sample for this test.
The Cholesterol test will calculate the Total Cholesterol, HDL cholesterol, together with a calculated ratio of the two – this ratio is used by healthcare professionals as a guide in determining the balance of “good” and “bad” cholesterol.

Back To Top

Total & Free PSA (Prostate Specific Antigen)

PSA is produced normally by the prostate gland and most of it is released into the semen. A small amount will enter the blood stream and can be measured by taking a blood test. In conditions which affect the prostate (not just cancer) where the architecture of the prostate is altered, more PSA is released into the blood stream leading to a raised PSA in a blood sample.
The PSA indicates your risk of having prostate cancer. It does not diagnose the disease itself. Therefore if you have a PSA greater than 10ng/ml, you will have a 50% chance of having prostate cancer. If your PSA is between 4-10 ng/ml, you will have a 25% chance of having prostate cancer. However even if your PSA is below 4ng/ml, it does not mean you do not have cancer but you would be at very low risk of having cancer. Oesterling JE. Prostate specific Antigen: a critical assessment of the most useful tumour marker for adenocarcinoma of the prostate. J Urol. 1991. 145, 907-923.
PSA can also be elevated due to:

• An enlarged prostate
• Prostatitis
• Catheterisation
• Prostate Surgery
• Urinary Tract Infection

A normal result may provide reassurance but does not absolutely rule out prostate cancer.
An elevated result may cause anxiety and may not lead to a diagnosis of prostate cancer.
PSA remains the best tumour marker for prostate cancer. It will lead to the diagnosis of men with prostate cancer, allow early treatment and then is used as a marker for monitoring treatment success.
PSA testing may be performed when a man has symptoms suggestive of prostate cancer such as difficult, painful, and/or frequent urination. It may also be ordered during and at regular intervals after prostate cancer treatment. Or to help determine the necessity for a biopsy of the prostate, to monitor the effectiveness of treatment for prostate cancer, and to detect recurrence of prostate cancer.

Back To Top

Serum Oestradiol

This test can be used to measure or monitor oestrogen levels if you are a woman who has unexplained abnormal menstrual cycles, abnormal or heavy bleeding, infertility, symptoms of menopause, or any other hormonal alterations; also used to test for the presence of female-like characteristics in males.
Oestradiol is also sometimes used to monitor menopausal hormone replacement therapy.
Taking oestrogen and progesterone supplements can affect results.

Serum Progesterone

This test can be used to help determine the cause of infertility, track ovulation, help diagnose an ectopic or failing pregnancy, monitor the health of a pregnancy, and help diagnose the cause of abnormal uterine bleeding.
Interpretation of progesterone test results requires knowledge of where a woman is in her menstrual cycle.
Taking oestrogen and progesterone supplements can affect results.

Back To Top

Serum DHEA-s

DHEAS, testosterone, and several other androgens are used to evaluate adrenal function and to distinguish between androgen secreting adrenal conditions from those that originate in the ovary or testes.
Concentrations of DHEAS are often measured, along with other hormones such as FSH, LH, prolactin, estrogen, and testosterone, to help diagnose polycystic ovarian syndrome (PCOS) and to help rule out other causes of infertility, amenorrhea, and hirsutism.
DHEAS concentrations peak after puberty, and then, like other male and female hormones, the levels tend to decline with age.

Serum Cortisol

Tests for cortisol are used to help diagnose Cushing's syndrome and Addison's disease, two serious adrenal disorders. Some physicians are using salivary cortisol to diagnose Cushing's syndrome as well as to evaluate stress-related disorders
Saliva tests are most frequently used to evaluate excess cortisol production.
Once an abnormal cortisol concentration has been detected, the doctor will do additional testing to help confirm the excess or deficiency and to help determine its cause.

Back To Top

Vitamin B12

B12, and an assortment of other tests may be ordered to help evaluate the general health and nutritional status of a patient with signs of significant malnutrition or malabsorption. This may include those with alcoholism and those with disorders associated with malabsorption such as celiac disease, Crohn’s disease, and cystic fibrosis.
In patients with known B12 and folate deficiencies, these tests may be ordered to help monitor the effectiveness of treatment. This is especially true in patients who cannot absorb B12 and/or folate and must have lifelong treatment.
When a person, especially an elderly person, exhibits mental or behavioral changes such as irritability, confusion, depression and/or paranoia, B12 and folate may be done to help diagnose the underlying cause. They may also be ordered when a patient has physical symptoms that suggest a B12 or folate deficiency, including dizziness, weakness, fatigue, or a sore mouth or tongue.
When a patient has symptoms suggesting nerve damage or impairment, such as, tingling, burning, or numbness in their hands, arms, legs, and or/feet, a B12 test may be requested to help diagnose the cause and detect the presence of a B12 deficiency.

Back To Top

Test Requirements:

All of the following tests require an unanticoagulated (clotted) serum sample
The Lipid Profile requires a fasting sample – i.e. no food or drink (other than water) for at least 8 hours prior to blood draw.

Back To Top

Iron/TIBC

Iron is needed to help form adequate numbers of normal red blood cells, which carry oxygen throughout the body. Iron is a critical part of hemoglobin, the protein in red blood cells that binds oxygen in the lungs and releases it as blood travels to other parts of the body. Low iron levels can lead to anemia, in which the body does not have enough red blood cells. Other conditions can cause too much iron to accumulate in your body. This can produce damage to several organs, including the liver, heart, and pancreas.
Iron status is evaluated by several tests that are not always run together. These include:

• Serum iron - measures the level of iron in the liquid part of your blood. 
• Total Iron Binding Capacity (TIBC) - measures the amount of iron that can be carried through blood by transferrin. Transferrin is the protein that transports iron from the gut to the cells that use it. Your body makes transferrin in relationship to your need for iron; when iron stores are low, transferrin levels increase and vice versa. In healthy people, about one-third of the binding sites on transferrin are used to transport iron. This number is called the transferrin saturation.
• Serum ferritin - reflects the amount of stored iron in your body; ferritin is the main storage protein for iron inside of cells. 

These tests are often ordered together, and the changes in each can help your doctor to determine if you have a deficiency or excess of iron in your body.

Back To Top

Intrinsic Factor Antibodies

Used to evaluate the cause of pernicious anaemia and/or decreased levels of Vitamin B12.

Glucose

The blood glucose test is ordered to measure the amount of glucose in the blood at the time of sample collection. It is used to detect both hyperglycemia and hypoglycemia and to help diagnose diabetes.
It is desirable for blood glucose to be measured on a fasting basis (sample collected after an 8 to 10 hour fast).

Back To Top

Selenium

A test to determine selenium deficiency

LFT (Liver Function Test)

A liver panel, also known as liver (hepatic) function tests or LFT, is used to detect, evaluate, and monitor liver disease or damage.

U & E (Urea & Electrolytes)

Test includes, Sodium, Potassium, Chloride, Urea and Creatinine

FBC

To determine general health status and to screen for a variety of disorders, such as anemia and infection.

ESR

The ESR is an easy, nonspecific test that has been used to help diagnose conditions associated with acute and chronic inflammation, including infections, cancers, and autoimmune diseases.
ESR is said to be nonspecific because increases do not tell the doctor exactly where the inflammation is in your body or what is causing it, and also because it can be affected by other conditions besides inflammation. For this reason, ESR is typically used in conjunction with other tests. ESR is helpful in diagnosing two specific inflammatory diseases, temporal arteritis and polymyalgia rheumatica. A high ESR is one of the main test results used to support the diagnosis. It is also used to monitor disease activity and response to therapy in both of these diseases.

Back To Top

Test Requirements:

The following tests require samples as set out below:

• Glucose – FX (grey top) tube

• Selenium – LH (green top) tube
• FBC – EDTA (purple top) tube
• ESR – Black top tube
• Red Cell Folate – EDTA (purple top) tube

All other blood tests require an unanticoagulated sample (yellow or red top) tube.

Back To Top