What to watch with FT4 and Fruchtbarkeit?

FT4 (free thyroxine) is a key thyroid marker reflecting active hormone availability. For fertility, an optimal FT4 level is critical: both overt hypothyroidism (low FT4) and subtle thyroid dysfunction can impair ovulation, menstrual regularity, and implantation. Evidence links even subclinical hypothyroidism (normal TSH but low-normal FT4) to increased miscarriage risk. Hyperthyroidism (high FT4) also disrupts cycles. However, FT4 alone is insufficient – TSH, TPO antibodies, and possibly fT3 should be assessed. For women trying to conceive, a target TSH <2.5 mU/L is recommended. Important: Thyroid hormones are prescription drugs; self-adjustment is dangerous. The evidence is based on endocrine guidelines and fertility research (human-moderate), not on the provided context snippets. Genetic variants (e.g., PCM1) have unclear relevance for thyroid-fertility interactions. Always consult a specialist for personalized interpretation.