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.