“…The baseline levels of serum iron, ferritin, folate, and VB12 are shown in Table 2, and their reference range is shown in Table S3. Twenty‐one studies 24,25,29–33,35,37–49 recommended prophylactic iron supplementations, 22 studies 21,23–25,29–33,35,37,39–49 recommended prophylactic folate supplementations, and 22 studies 21,23–25,29–35,37,39–46,48,49 recommended prophylactic VB12 supplementations. According to the guidelines of the AACE‐TOS‐ASMBS, seven studies 24,29,38,42,43,46,47 were sufficient for iron supplementations, seven studies 32,42,43,46–49 were sufficient for folate supplementations, and four studies 34,42,43,46 were sufficient for VB12 supplementations.…”