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Subclinical Hypothyroidism

Imran Bashir

Subclinical hypothyroidism • TSH above the limit of reference range when FT4 levels

are normal• Prevalence 4-15%• Prevalence rises with age, higher in females

SH • Can be an incidental finding• Can present with non-specific symptoms of

hypothyroidism like fatigue, constipation• Patients with chronic autoimmune thyroiditis• Prior ablative or anti thyroid drug therapy• Drugs impairing thyroid functions• Most patients with TSH < 10 are asymptomatic• If elevated, should be repeated with FT4 levels

SH: D/D• During period of recovery from nonthyroidal illness• Untreated adrenal insufficiency • TSH producing pituitary adenomas and resistance to

thyroid hormone• Central hypothyroidism

SH: Progress• Spontaneous recovery• Overt hypothyroidism • Cardiovascular risk & neuropsychiatric symptoms

SH: treat or not treat?• TSH values 4.5-10, unlikely to benefit• Those with sign and symptoms and TSH 10-15 likely to

benefit• Treatment in specific group of population

Prospective evaluation of the natural course of idiopathic subclinical hypothyroidism in childhood and adolescence Malgorzata Wasniewska, Mariacarolina Salerno1, Alessandra Cassio2, Andrea Corrias3, Tommaso Aversa, Giuseppina Zirilli, Donatella Capalbo1, Milva Bal2, Alessandro Mussa3 and Filippo De Luca

• Prospective study to evaluate course of SH in children & adolescents

Design • Clinical status, thyroid function, and autoimmunity

evaluated at entry, 6, 12 & 24months in 92 patients with idiopathic SH

• Did the study address a clearly focused issue?

– Yes: prospective study for children with subclinical hypothyroidism

• Did the author use an appropriate method to answer their question?

– Yes: Prospective study is the best way to evaluate the progress

Results• 38 patients normalized their TSH (Group A)

– 16 between 6-12 months– 22 between 12-24 months

• 54 maintained TSH within baseline values (Group B)• 11 exhibited a further increase in TSH (Group C)• No patient showed any signs of hypothyroidism

Results• Majority of patients (88%) normalized or maintained their

TSH• TSH changes were not associated with either FT4

values or clinical status or auxological parameters

• Was the cohort recruited in an acceptable way?

– Yes: appropriate inclusion and exclusion criteria used

• Was the exposure accurately measured to minimize bias?– Yes

• Was the outcome accurately measured to minimize bias?– Yes:

• Confounding factors accounted for?

– Possibly yes• Family history not very well explained

• Was the follow up of subjects long enough?

– Can’t tell: Probably long term follow up is required to see progress of TSH and FT 4

• How precise are the result? And do we believe the results?– Yes: Same laboratory and analyzer used

• Can the results be applied to local population?

– Yes: With same group of subclinical hypothyroid children who don’t have any clinical sign & symptoms or risk factor for thyroid disease.

• Do the results of the study fit with other available evidence?

– Can’t tell: Need more randomized multicenter trials

Thank you….