thyroxine levels normal range
Reference ranges for total thyroxine (TT4) are as follows: 1  In newborns up to age 14 days: 11.8â22.6 mcg/dL (152â292 nmol/L) 2  In babies and older children: 6.4â13.3 mcg/dL (83â172 nmol/L) 3  In adults: 5.4â11.5 mcg/dL (57â148 nmol/ L)