Hyperthyroidism
28
Flowchart 4. Approach to Decreased TSH Levels in Pregnancy
TSH <0.10 mU/L
in pregnancy
Check FT4
and (F)T3
Normal FT4
and (F)T3
Green boxes indicate a diagnosis, yellow boxes indicate an action, and orange boxes indicate
recommended follow-up. (F)T3 = serum free and/or total T3 (See Box 5).
a
For women with a clear presentation of hCG-induced hyperthyroidism/gestational transient
thyrotoxicosis (for example with a non-fully suppressed TSH, twin pregnancy, or hyperemesis
gravidarum without extrathyroidal signs of Graves' disease), it is reasonable to follow-up with a TSH
and FT4 in 2–4 weeks before checking TRAb and/or TSI.
Repeat TSH and FT4
every 2–4 weeks
• Additional work-up
• Restart flowchart
No follow-up,
contact if symptoms
Subclinical
hyperthyroidism
Stable
TSH/FT4
b
Biochemical
progression
Euthyroidism
