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A Comprehensive Guide to Blood Testing

Introduction to Blood Testing

Blood testing is an insightful way to understand things about our health, and when done at the right time and in the right context, is an excellent tool for helping to solve your health issues.

It is important to follow instructions to the letter regarding blood testing and also to make sure that you are prepared so that the doctors or healthcare professionals analysing your results will have the right information.

When blood testing is done correctly, the results can enhance someone's treatment and give insight into particular conditions or diseases.

Introduction to Blood Testing

What is Blood Testing?

Blood testing is a medical procedure in which a sample of your blood is collected and analysed in a laboratory. Blood tests are a common diagnostic tool used by healthcare professionals to assess various aspects of your health. They provide valuable information about your overall health, specific medical conditions, and the functioning of various organs and systems in your body.

Blood testing can help your doctor or naturopath to understand your symptoms more clearly, and can provide clues about your body system such as the immune system, digestive system, liver function, hormones, blood sugar regulation, and thyroid health. For example, if you are suspected to have diabetes, your healthcare provider might request blood testing for fasting insulin and glucose to check how your body is handling carbohydrates.

Each type of blood test comes along with reference ranges. This is usually based on a survey of a healthy population as a guide for what is acceptable. In some cases, the reference range numbers only rule out disease, but aren't representative of what is 'optimal'. Here is some information about what is involved when you get a blood test:

Types of
Blood Tests

Blood testing can measure a wide range of parameters in the human body. It can look at the composition of blood cells, detecting abnormalities in red blood cells, white blood cells, and platelets, aiding in the diagnosis of conditions such as anemia and infections.

In addition, blood chemistry panels evaluate the levels of various substances like glucose, cholesterol, electrolytes, and proteins, offering insights into diabetes, liver and kidney function, and cardiovascular health.

Coagulation tests assess the blood's clotting ability and are vital for diagnosing bleeding disorders and monitoring clotting disorders. Blood gas analysis measures oxygen and carbon dioxide levels, crucial for evaluating respiratory function, while hormone assessments can pinpoint thyroid issues, hormonal imbalances, and diabetes.

Blood testing is also invaluable in detecting infections, allergies, and genetic predispositions, contributing significantly to both preventive and diagnostic healthcare practices.

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Benefits of Blood Testing

Blood testing can help with:

Diagnosing current and past infections, such as Epstein Barr Virus (EBV)
Looking into hormonal imbalances
Checking thyroid, iron, and electrolytes to investigate fatigue
Finding out about mineral and vitamin deficiencies such as Vit D, B vitamins, and zinc or magnesium
Preparing for preconception by looking at thyroid, selenium, iron, B vitamins, folate, and hormone levels
Investigating autoimmune conditions such as Hashimotos, Lupus, or Sjogren's disease
Discovering if you have a genetic predisposition to a certain cancer
Monitoring for hereditary diseases

Testing for coeliac disease if you have digestive issues

Blood testing for allergies such as mould, animals, dust
For anyone suspected of having a heart attack or a stroke to determine what has happened
Verifying the effectiveness or appropriateness of medications and supplements
Checking liver function

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Risk of Blood Testing

Pain or discomfort

Some people may experience mild pain or discomfort when the needle is inserted into the vein to draw blood or when the tourniquet is tightened. This discomfort is usually temporary and subsides once the needle is removed.


It is common to develop a small bruise at the site where the needle was inserted. This is usually minor and resolves on its own within a few days.


Although rare, there is a small risk of infection at the puncture site. Healthcare providers take precautions to minimize this risk, such as using sterile equipment and cleaning the area before the blood draw.

Fainting or lightheadedness

Some individuals may feel faint or lightheaded during or after a blood draw. This is more common in people who have a fear of needles or a history of fainting during medical procedures.


In some cases, blood can leak from the puncture site and collect under the skin, forming a hematoma (a localized collection of blood). Hematomas are usually not serious but can cause swelling and discomfort.

Nerve damage

Extremely rare, but there is a risk of nerve damage if the needle is inserted too deeply or in the wrong location. Proper training and technique by the healthcare provider help prevent this.

Allergic reactions

Although exceedingly rare, it is possible for individuals to have an allergic reaction to the antiseptic used to clean the puncture site or to the materials used in the blood collection tubes. Allergic reactions can range from mild skin irritation to severe allergic reactions (anaphylaxis).

Blood clotting disorders

In individuals with certain blood clotting disorders, there may be an increased risk of bleeding complications during or after a blood draw. Healthcare providers should be aware of such conditions and take appropriate precautions.

Incorrect results

Blood test results can sometimes be inaccurate due to various factors, including laboratory errors, sample contamination, or issues with the collection process. This can lead to misdiagnosis or unnecessary follow-up testing.

Preparing for a Blood Test

Before your blood test appointment, it is important to ensure you are getting the testing done on the right date and time.

For some hormones, they must be tested at a particular time in your menstrual cycle, and for other hormones, it's important to test at a certain time during the day. Some testing requires you to attend fasting, meaning no food in the 24 hours before, and other testing must be done after you eat a meal. At the pathology collection center, the staff will ask you to confirm your personal details before taking your blood.

Generally, it is a good idea to make sure you are well hydrated, as this can make it easier for your nurse to find your veins. If you are someone who gets nervous around blood or has a needle phobia, you should let staff know how you are feeling in case you feel light-headed or faint.

Common Blood Tests

Iron studies
Liver function
Immune markers
Blood glucose
Thyroid-stimulating hormone

Interpreting Blood Test Results

To interpret blood test results accurately, it's necessary to know when they were done, and often requires the context of other testing markers to make sense.

For example, fasting insulin testing must be done first thing in the morning on an empty stomach, not after exercise or any supplements are taken.

When we review thyroid stimulating hormone (TSH) it's also important to look at your thyroid hormone production, so we need to review T3 and T4. Without these, we can't fully understand how the thyroid is working.

Another important aspect is to take into account the person's symptoms to understand how the results might affect someone's health.

Factors that Affect Blood Test Results

Fasting or Non-Fasting Status

Some blood tests, like fasting blood glucose and lipid panels, require the patient to fast for a certain period before the test. Eating or drinking before these tests can significantly affect the results.

Time of Day or Month

Certain hormones and analytes in the blood exhibit diurnal or monthly variations. For example, cortisol levels are highest in the morning, and progesterone is highest in the luteal phase of a woman's menstrual cycle.


Pregnancy can affect numerous blood parameters, including hormonal levels and blood cell counts. Specialized pregnancy-specific reference ranges are used for many tests during pregnancy.

Recent Illness or Infection

Acute illnesses or infections can lead to transient changes in blood parameters, such as an elevated white blood cell count.

Lab Variability

Different laboratories may have slightly different methods and equipment, which can result in variations in test results.

Alcohol and Caffeine

Alcohol and caffeine consumption can affect various blood tests, including liver function tests and lipid panels.

Recent Exercise

Intense physical activity before a blood test can lead to temporary changes in blood parameters such as creatine kinase, which is elevated after strenuous exercise.


Not drinking enough fluids can cause an increase in the concentration of certain substances in the blood, such as electrolytes.

Age and Gender

Normal reference ranges for some blood parameters can vary with age and gender. Pediatric and geriatric populations may have different reference ranges for some tests.

Stress and Anxiety

Emotional stress can lead to the release of stress hormones like cortisol and adrenaline, which can affect some blood test results.

Recent Meals

Even when fasting is not required, the composition of recent meals can influence certain blood tests. For example, a high-fat meal can temporarily raise triglyceride levels.

Medications and Supplements

Many medications and supplements can alter blood test results. This includes prescription drugs, over-the-counter medications, and herbal supplements. It's crucial to inform your healthcare provider about all the medications and supplements you are taking.


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Blood Testing for Specific Conditions

To interpret blood test results accurately, it's necessary to know when they were done, and often requires the context of other testing markers to make sense.

For example, fasting insulin testing must be done first thing in the morning on an empty stomach, not after exercise or any supplements are taken.

When we review thyroid stimulating hormone (TSH) it's also important to look at your thyroid hormone production, so we need to review T3 and T4. Without these, we can't fully understand how the thyroid is working.

Another important aspect is to take into account the person's symptoms to understand how the results might affect someone's health.

  • Fasting Blood Glucose Test: Measures blood sugar levels after an overnight fast. Elevated levels may indicate diabetes.
  • Hemoglobin A1c (HbA1c) Test: Provides an average of blood sugar levels over several months, helping to assess long-term glucose control.
  • Cholesterol Panel: Measures levels of total cholesterol, LDL (low-density lipoprotein), HDL (high-density lipoprotein), and triglycerides to assess cardiovascular risk.
  • High-Sensitivity C-Reactive Protein (hs-CRP): Evaluates inflammation associated with heart disease risk.
  • Troponin: Detects cardiac damage, often used in diagnosing heart attacks.
  • Thyroid Function Tests: Include tests like TSH (thyroid-stimulating hormone), free T4, and free T3 to assess thyroid gland function and diagnose conditions like hypothyroidism or hyperthyroidism.
  • Complete Blood Count (CBC): Assesses red blood cell count, hemoglobin, hematocrit, and other parameters to diagnose anemia and identify its cause.
  • Iron Studies: Measure iron levels, total iron-binding capacity (TIBC), and ferritin to determine iron-deficiency anemia.
  • Liver Function Tests: Include tests like ALT (alanine aminotransferase), AST (aspartate aminotransferase), ALP (alkaline phosphatase), bilirubin, and albumin to evaluate liver health and diagnose liver diseases.
  • Basic Metabolic Panel (BMP) or Comprehensive Metabolic Panel (CMP): Assess kidney function through tests like creatinine, BUN (blood urea nitrogen), and electrolyte levels.
  • Glomerular Filtration Rate (GFR): Estimates the kidney's filtration rate, often used to stage chronic kidney disease (CKD) or kidney failure.
  • Autoantibody Tests: Identify specific autoantibodies associated with conditions like lupus, rheumatoid arthritis, or celiac disease.
  • Erythrocyte Sedimentation Rate (ESR) or C-Reactive Protein (CRP): Elevated levels may indicate inflammation associated with autoimmune conditions.
  • PSA (Prostate-Specific Antigen): Used for prostate cancer screening.
  • CA-125: May be elevated in ovarian cancer.
  • CEA (Carcinoembryonic Antigen): Elevated in some types of cancer, including colorectal cancer.
  • Hormone Panels: Assess hormones like testosterone, estrogen, progesterone, and others to diagnose hormone-related conditions or imbalances.

  • Complete Blood Count (CBC): This can reveal an elevated white blood cell count, which may indicate an infection.
  • Specific Antibody Tests: Detect antibodies against pathogens like HIV, hepatitis, or various bacteria and viruses.

Expert Advice on Blood Testing

When you require blood testing, it's important to know the best time to do it so that the results are accurate. Always remember to ask the GP or health practitioner if you are required to fast, and what time of the day or month you should do the blood testing. Sometimes blood testing is not enough to get to the bottom of your symptoms, which is why it can be necessary to do further testing, such as stool testing, saliva testing, or even urine testing in some cases.

Even if your blood test results come back 'normal' they might not be in the optimal range, so it's important to always keep a record of all testing in case your naturopath might want to review the results.

Blood Testing with a woman in the office

Common Questions: Blood Testing Myths Debunked

MYTH: As mentioned, your blood test results can be in the reference range but not the optimal range. As an example, iron levels might be in the reference range, but for someone who is trying to fall pregnant and will need high iron levels, they might be at the lower end of the range. 
MYTH:Blood tests are usually performed by a trained medical professional, such as a doctor or nurse.
MYTH: Knowing what day of your menstrual cycle is integral to interpreting your hormone results, but it's definitely not pointless.
FACT: Unless the blood testing is covered by Medicare or your health care fund, blood testing can cost anywhere from $50 up to $300.
FACT:Unless there are special requirements, the average turnaround can be 1-2 days for most blood testing.
FACT:Blood testing can check for infections of things such as HIV, hepatitis, and syphilis.
FACT: This is correct. Blood testing can look at all of these elements to determine the overall health.

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Seek advice from a health professional

Blood testing can be extremely helpful for understanding someone's condition or symptoms, but only when taken at the right time and interpreted correctly by a health professional.

As Naturopaths, our job is to look at all the evidence to piece together what is happening to your health, and often, the first step is testing so we have a clear answer.

However, as mentioned, sometimes blood testing doesn't tell us the whole picture, which is where functional testing comes in handy to explore your hormones, gut, or stress levels.

If you are unsure about your health or recent test results, reach out to book with us so we can put your mind at ease!

Book an online or in-person consultation, or give us a call.

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