- Subclinical Hypothyroidism as defined by an elevated TSH (≥ 3.00 mU/L) and a free-T4 in the normal range (i.e. 0.86 to 1.90 ng/dL) or Hypothyroxinemia as defined by a TSH in the normal range (0.08 to 2.99 micrometers (mU)/L) and a low free-T4 (<0.86 ng/dL)