Pregnancy Subject index

It must be appreciated that the same factors that affect total T< levels have a similar, although less pronounced, effect on total Tj. For example, pregnancy and the administration of oral contraceptives, through their TBG-elevating effect, significantly elevate the serum total T3 concentration in euthyroid subjects (B21). The reader is also referred to Fig. 4. Unfortunately, the calculation of a free Ts index is not necessarily a valid procedure, and furthermore, there is as yet, no uniformity in tlie performances of various free T3 concentration procedures, nor is any simple enough for routine assay. 

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