A prolactin blood test measures the level of prolactin, a hormone, in the bloodstream. This common diagnostic tool helps healthcare providers evaluate various health conditions. Accurate results rely on proper patient preparation before the blood draw.
Fasting for Your Prolactin Test
Fasting is generally not required for a prolactin blood test. Unlike tests for glucose or cholesterol, where food intake directly influences results, prolactin levels are not typically affected by recent eating. Therefore, individuals usually do not need to abstain from food or drink before their blood sample is collected.
While fasting is broadly unnecessary, it is important to follow any specific instructions from your healthcare provider or the laboratory. Protocols can vary depending on the specific reason for the test or the laboratory’s internal guidelines. Adhering to these instructions ensures the most reliable and accurate measurement of prolactin levels.
What Prolactin Is and Why the Test is Done
Prolactin is a hormone primarily produced by the pituitary gland, a small gland at the base of the brain. Its primary role is stimulating milk production (lactation) in women after childbirth. It also influences reproductive health in both men and women, affecting menstrual cycles, fertility, and sexual function.
Healthcare professionals order a prolactin blood test for various reasons. The test can investigate symptoms like unexplained headaches or visual disturbances, which may indicate a pituitary issue. It also evaluates irregular menstrual periods, infertility, or nipple discharge (galactorrhea) in women who are not pregnant or breastfeeding. In men, it assesses symptoms such as erectile dysfunction, reduced libido, or breast enlargement (gynecomastia).
Other Factors Affecting Prolactin Levels and Test Preparation
Beyond fasting, several other factors can influence prolactin levels and require attention before a blood test. The timing of the blood draw is significant; healthcare providers typically recommend the test be done in the morning, ideally within three to four hours of waking. This timing helps capture baseline prolactin levels, as they can fluctuate throughout the day.
Avoiding certain activities before the test is also important for accurate results. Stress, vigorous exercise, and sexual activity can temporarily elevate prolactin levels, potentially leading to a misleadingly high reading. Patients are usually advised to avoid these activities for several hours, or even the day before, their scheduled blood test. Individuals should also discuss any medications with their doctor, as some drugs can affect prolactin levels and might need temporary adjustment or notation before the test.