Is the menstrual cycle affecting the skin prick test reactivity?

Allergen skin prick tests (SPT) are very sensitive and specific tests to detect allergic sensitization in atopic patients. Certain factors like antihistamines, antidepressant therapies or circadian rhythms can alter the results of SPT. In women, the changes in endogenous hormone levels throughout the menstrual cycle may affect the allergic responses and natural course of allergic diseases. The aim of this study was to investigate the probable influence of the phases of the menstrual cycle on SPT reactivity to allergen extracts and histamine. Forty-two female patients with seasonal allergic rhinoconjunctivitis were enrolled in the study. Skin prick test reactivities to allergens and histamine were measured at the beginning of the menstrual cycle (3rd or 4th day), mid-cycle (14th or 15th day) and end-cycle (27th or 28th day) consecutively. Serum estradiol, progesterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) levels were determined simultaneously. We observed the most significant reactions to allergens when SPT is performed at mid-cycle. However, SPT reactivity to histamine did not vary throughout the menstrual cycle. Serum estradiol and LH levels showed positive correlation with SPT reactivity to allergens at mid-cycle. Our results suggest that SPT give the best results when they are performed at mid-cycle. Additionally, allergens seem to cause mast cell degranulation to a greater extent in subjects in which endogenous hormones like estradiol and LH are elevated.