Thyroid Physiology

Screening for thyroid disease

Laboratory evaluation of thyroid function



Thyroid Disorders in Pregnancy


"Nontoxic goiters" & Thyroid Nodules

Definitions of thyroid disorders

  1. "Subclinical hypothyroidism" = elevated TSH but normal T4 (aka "mild thyroid failure")
  2. "Subclinical hyperthyroidism" = low TSH but normal T4
  3. "Overt hypothyroidism" = elevated TSH and low T4
  4. "Overt hyperthyroidism" = low TSH and elevated T4
  5. "Sick Euthyroid" syndrome (aka "nonthyroid illness syndrome")-Low T3 with low or normal T4 and TSH normal or high (but rarely > 20 microunits/mL) in setting of severe non-thyroid illness
  6. All of the above can be symptomatic or asymptomatic
  7. Symptomatic hyper- or hypothyroidism can be "clinically apparent" or "clinically inapparent," i.e. sx exist but not suspected to be due to thyroid dysfunction
    1. Prevalence of symptomatic, clinically inapparent thyroid disease is about 1.4% in women > 50yo
    2. Prevalence much less in women < 50yo