Hypothyroidism — High TSH

Dx:     High TSH, Low Free T4

Subclinical:  Slight ↑ TSH, Normal Free T4
  • Treat TSH >15 mU/L
  • Don’t Treat <10 mU/L   (10-15 mU/L equivocal)
 Central (rare):  low FT4
  • TSH maybe low or normal
 TSH in Pregnancy: Adjust Values
  • Non-Pregnant:    0.4 – 4.5 mU/L
  • 1st Trimester:      0.1 – 2.5
  • 2nd Trimester:      0.2 – 3.0
  • 3rd Trimester:      0.3 – 3.0
T4 in Pregnancy
  • Free T4: Use specific lab kit values for pregnancy.
  • Total T4:  Multiply x 1.5
Newly Dx’d Pregnancy in Hypothyroid Pt. on Tx:
  • Increase L-Thyroxine dose by 1/3  [to avoid miscarriage]
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