It is not unusual for blood test results to differ from one blood draw to another or from one lab to another. This variance can be confusing to a patient and challenging for a physician.
Why does it occur? Multiple factors may contribute to the variation:
- Time the blood sample was taken: Hormone levels and other biomarkers vary during the day and often are higher in the morning vs evening.
- Timing of your lab in relation to when you take your medication: Taking a testosterone injection and then getting a lab the following day vs getting a lab the day before your next injection can show dramatic differences.
- Diet: Fasting and/or the type of foods you eat and the fluids you drink can affect blood levels.
- Exercise: The timing of your exercise in relation to your lab draw can affect lab results.
- Intimacy / ejaculation / nipple stimulation: Affect levels of testosterone, prolactin, prostate specific antigen, etc.
- Sickness and Stress
- Medications / Supplements
- Sleep: Getting a good night of sleep vs pulling an all-nighter can impact your hormone levels the following day.
- Calibration of instruments
- Differences in lab equipment from one lab to another
- Difference in analyzing techniques from one lab to another
- Blood sample handling and storage
So, what can you do to help ensure an accurate reading?
- With your initial labs, follow up labs or additional labs be sure to carefully follow the instructions when testing.
- Know that your Hone physician has been well trained in lab variance and will help you make sense of your lab values.
- Don’t be surprised if on occasion you may be asked to repeat a lab in order to determine the correct treatment plan.