What to watch with FT3 and Fruchtbarkeit?

FT3 (free triiodothyronine) is an active thyroid hormone marker. Both low and high levels can impair fertility by disrupting ovulation, egg quality, and endometrial receptivity. Thyroid screening is standard in fertility workups, but TSH is the primary marker; FT3 and FT4 provide additional nuance. Isolated low FT3 with normal TSH may indicate 'low T3 syndrome' often seen in chronic illness or caloric restriction, which can reduce fertility. Caveat: a single FT3 value without TSH, FT4, and antibodies is insufficient for diagnosis. MyBody-X tests may measure these markers, but interpretation requires an endocrinologist. Evidence for FT3-fertility link is human-moderate (observational studies, no large RCTs).