What do my lab results mean?

They say your eyes are a window to your soul — but did you know that your blood is a window to your health?

There are plenty of ways your doctor can look inside your body, from X-rays to MRIs to ultrasounds. These are all important tests that save lives every day. However, there’s another simple way to take a look at what’s happening inside your body: a blood test.

Your blood is a special fluid, and it has many important roles. From bringing oxygen and nutrients to your organs to carrying around important cells that fight infections, your blood is essential to your livelihood. About 7 to 8% of your body weight is blood, and by taking a small sample of it, your doctor can find out a lot about your health.

Most lab results are accompanied by a set of numbers called a reference interval. These are present to assist your doctor to interpret the results in a meaningful way. There are two main types of reference intervals, ‘population-based’ and ‘health-based.’

Population-based reference intervals:

These are obtained after statistical analysis of results from a representative normal, disease free population. Often reference intervals are further partitioned to consider result differences in sub populations of people. This is usually the case for age and gender, as there can be significant physical and hormonal differences between males and females, and adults and children, for example with regards to haemoglobin levels.

Most commonly, 95% of healthy people would be expected to fall within these values. As a result, some normal, healthy individuals may return a result that is outside of this range. For example, some abnormal test results may be temporary, such as biochemical changes that may occur after physical exercise. Therefore, it is important to understand that having a result outside of the reference interval may not be cause for concern and may in fact still be normal for you. Your doctor will evaluate your result in the context of your medical and personal history to determine whether the result is significant. Follow-up may include repeating the test on a separate occasion or performing confirmatory or complementary testing that may assist in the interpretation.

Health-based reference intervals:

Some tests are compared against health-based reference values, which are values that are associated with optimal health and reduced risk of disease and/or disease related complications. This includes vitamin D, which has such a high prevalence of deficiency in the population, that comparing against most people in the population would not indicate a desired result. Additional lab tests based upon health-based reference intervals include glucose and haemoglobin A1c (a marker of long-term glycaemic control) which are partitioned into the categories, normal, pre-diabetic, and diabetic, based on the risk of long-term diabetic complications relating to micro- and macrovascular disease.

What could alter my result?:

Unless otherwise specified, reference intervals generally don’t consider factors such as diet (including fasting), time of day, physical activity, medications, or posture, which may alter the results of the test. It is crucial that all information is disclosed to your doctor, so that informed decisions can be made about your results. This is especially important regarding medications, where both prescription and non-prescription medications may cause false results through interference with the methodology of the test. This includes supplements such as biotin, which is found in large amounts in hair, skin, and nails supplements, and can have a significant effect on some tests. Some medical conditions that produce excess substances, such as rheumatoid factor in rheumatoid arthritis, may contribute to false results for some tests.

Comparing results from different labs:

Different labs may use different kinds of instruments and different testing methods, so it is important to apply the reference interval supplied by the laboratory to the results they have produced. Although some results may be similar, there may be some that are significantly different between labs. Also, tests can be reported in different units. Like how length may be reported in metres or yards, tests can be reported in different units and have reference intervals to reflect this.

At GluCare, our in-house lab performs most routine tests in real-time, normally within 30 minutes for most tests, enabling you to complete your journey on the same day. Our laboratory technologists have a collaborative working relationship with your doctors to ensure that all results are high quality and concerns are investigated in conjunction with clinical and personal history.