It’s not uncommon to have multiple labs provide results for the same blood test at various points in time. Doctors may prescribe lab tests to keep tabs on a patient’s health, evaluate a treatment’s efficacy, or rule out the possibility of erroneous positive or negative results.

The results should be consistent if the samples were collected in the same way and tested with the same method. On the other hand, blood tests may provide varying results based on a number of factors, such as the laboratory performing the analysis, the time of day the sample was collected, and so on.

This occurs since different laboratories utilize varying methods, storage conditions, and analytical tools when processing materials. There may be some variation in test findings even when laboratories employ the same instruments and procedures.

But what if there’s a big discrepancy in the findings? What causes this, and how can it be stopped? You may learn more about it below.

Determining Your Target Range

You’ll also see a reference or target range alongside your actual results. Within these bounds, results are often expected to be within the norm. It was derived from a massive sample of healthy individuals. Your doctor will use this range as a benchmark to analyze your lab results. If your results are significantly different from this range, further investigation may be warranted to determine the cause. The magnesium blood test, for instance, has a reference range of 1.7–2.2 mg/dL.

Depending on the characteristics of the control group, the goal ranges established by different laboratories may vary. For those of African, Mediterranean, or Southeast Asian origin, the HbA1C test may give an inaccurate result because they may have a kind of hemoglobin that messes with the test.

It is possible that a result beyond the normal range in a healthy person does not necessarily indicate the existence of a disease. If you want to make sense of your results, it’s best to talk to a doctor.

Factors That May Affect the Blood Test Results

Vitamin D, cortisol, glucose, and other chemicals can all be used as biomarkers because they can be evaluated in the blood. They are measured in a blood test, and their concentrations might change for several causes. Normal blood test results may be affected by the following variables.

  • The Time of Day, Eating Habits, and Water Intake

Biomarker concentrations in the blood might change throughout the day. An excellent illustration of a biomarker that changes throughout the day and in response to diet is thyroid stimulating hormone (TSH), which is elevated after a fast.

Blood levels of numerous biomarkers can be affected by an individual’s diet and fluid intake. Since blood glucose levels can change depending on diet and exercise, the HbA1C blood test is a good example of a flexible diagnostic tool for diabetes. A similar biomarker of kidney function, blood urea nitrogen (BUN), tends to rise in people who are dehydrated.

Blood tests require strict protocol adherence, particularly regarding timing, diet/fasting, and hydration.

  • Stress and Health Conditions

The amounts of biomarkers may be temporarily altered by certain situations. Sickness and stress, for instance, might have an effect on blood glucose, which can then affect HbA1C values.

  • Changes in Cyclical Hormone Levels

Iron, lipid (cholesterol) levels, vitamin D, and high-sensitivity C-reactive protein (hsCRP) levels are only a few biomarkers whose levels might change throughout the menstrual cycle. After menopause, TSH levels can drop below the normal range and during menstruation, pregnancy, and menopause.

  • Medications

The outcomes of blood tests may be affected by medication. A number of medications, including glucocorticoids and chemotherapeutic medicines, work to reduce TSH levels in the body. Nonsteroidal anti-inflammatory drugs (NSAIDs), heparin, and the B vitamin complex component biotin can all skew TSH test results even if they don’t affect hormone levels. Some antibiotics and other medicines can impact creatinine test results; if necessary, your healthcare provider may instruct you to temporarily discontinue their use before the test.

So that they can properly interpret your results, it is essential that your healthcare practitioner is aware of any and all drugs, vitamins, and other treatments you are currently taking.


It’s important to understand that blood test results may vary for a variety of reasons. Sometimes, they may be affected by the way the blood was drawn or processed. Other times, different laboratories may use different methods to measure the same thing, which can lead to different results.

If you’re concerned about your blood test results, it’s important to talk to your doctor. They can help you understand what they mean and whether you need to take any follow-up steps.

If you are looking for an institution that provides blood test services in Troy, look no further than our services here at Family Medicine and Wellness. We believe that health and wellness are of utmost importance for well-being and are attained through a personalized patient-physician relationship. Call us today to book your first blood test appointment with us.