Subclincal Thyroid Disease and the Work-up of a Thyroid Nodule Jared Bunevich MS IV LECOM

Objectives Discuss the diagnosis and clinical presentation of subclincal hypothyroidism Discuss the controversies surrounding treatment of subclincal hypothyroidism Discuss the diagnosis and clinical presentation of subclincal hyperthyroidism Discuss the controversies surrounding the treatment of subclincal hyperthyroidism Discuss cost-effective and clinically based work-up of a Thyroid Nodule

Subclinical Hypothyroidism Definition: Increased TSH levels in the face of normal free thyroxin (T4) Even though referred to as subclinical, patients still may have symptoms (fatigue, weight gain, muscle loss)

Subclinical Hypothyroidism Diagnosis Increase serum TSH and free T4 within the normal range Measurement of TSH is sensitive and specific, even though free T4 levels maybe within normal limits the actual levels of T4 maybe less than that patient previously had 7% of women and 3% of men aged 60-89 were found to have TSH greater than 10 uU per mL without obvious hypothyroidism clinical findings Risk Factors for Diagnosis: family history of thyroid disease, autoimmune disease, previous head and neck radiation, drugs (lithium, amiodarone)

Subclincal Hypothyroidism Guidelines: U.S. Preventive task force recommends routine universal screening NOT be carried out on asymptomatic patients because clinical benefit is insufficient American Thyroid Association recommends screening in men and women every five years beginning at age 35

Subclincal Hypothyroidism

Subclinical Hypothyroidism Course: TSH may return to normal after several month reassessment and can be attributed to: Lab error Silent thyroiditis Sub clinical hypothyroidism with detectable antithyroid antibodies progesses to overt hypothyroidism at about 5% per year, and maybe as high as 20% in the elderly and patients with high antithyroid antibodies

Subclinical Hypothyroidism Symptoms: In studies comparing euthyroid individuals and subclinical hypothyroid easy fatigability, cold intolerance and dry skin were more common in the subclincal hypothyroid group Arem et al and Franklin et al found a decrease in the LDL of patients with subclincal hypothyroidism when treated with synthyroid Cooper et al found the PEP:LVET was found to significantly improve in subclincal patients when treated with levothyyroxine

Subclincal Hypothyroidism When should we treat? When TSH is consistently 10 uU/mL on two or more occasions six months apart and the patient has increased antithyroid antibodies Persons who have hypothyroid type complaints and elevated TSH should be treated (even if TSH is in the 5-10 uU/mL range)

Subclinical Hypothyroidism

Subclinical Hypothyroidism Treatment options Overt Hypothyroidism Typical Patient Start with Levothyroxine 25-50 ug daily and increased slowly by 25-50 ug to 75 or 100 ug Elderly and the Patients with heart disease Start a lower doses and progress at smaller increments to 50 or 100 ug or 1.6 ug/kg Subclinical Hypothyroidism Levothyroxine 25-50 ug with a repeat TSH in 6 weeks with the goal of maintaining TSH in the normal range Smaller overall dosages are more commonly utilized

Subclinical Hyperthyroidism

Subclinical Hyperthyroidism Diagnosis Definition: normal serum free thyroxine and free triiodothyronine with a TSH suppressed below the normal levels Physical exam will NOT yield an enlarged thyroid gland

Subclinical Hyperthyroidism Differential Diagnosis Silent thyroiditis Steroid use Dopamine administration Pituitary dysfunction Early Hashimoto’s or Graves disease Multinodular goiter (particularly in the elderly)

Subclinical Hyperthyroidism Etiology Vanderpump et al found subclinical hyperthyroidism progresses to overt hyperthyroidism at 1-3% year There is an increased risk of cardiac and bone density abnormalities

Subclinical Hyperthyroidism Cardiac Abnormalities A-fib risk increased 3-5 fold in persons older than 60 with decreased TSH values (Sawin et al) A small study showed resting baseline left ventricular diastolic filling was impaired at maximal exercise In addition patients increased interventicualr wall thickness

Subclinical Hyperthyroidism Bone Density Premenopausal women with subclinical hyperthyroidism do NOT appear to be at risk for increased bone loss 41 studies including 1200 postmenopausal patients found patients with suppressed TSH values were associated with significant bone loss in the lumbar spine and femur

Subclinical Hyperthyroidism Neuropsychiatic: Boomer et al Reduced feelings of well being Inability to concentrate Feelings of fear

Subclinical Hyperthyroidism Diagnostic Assessment TSH, T3, T4 evaluation Monitor for three months if indicative of subclinical hyperthyroidism If TSH concentration remains suppressed a RAIU is indicated with possible sonography Also, in elderly patients consider ECG, bone mineral density exams

Subclinical Hyperthyroidism Treatment options Antithyroid medications PTU 50-100 mg /day Mehtimazole 5 mg /day if not pregnant Initiate if RAIU is positive or if patient is symptomatic for 6-12 months Surgery Non-complaint or patients who develop Garves, Hashimoto’s Radioactive iodine Only cost-effective if medical therapy fails x2

Thyroid Nodule Work-up Clinical Hx Consider Age Malignancy is higher in youth with nodules Sex Less common in men but more likely to be malignant Family history History of neck radiation 0.5 Gy increases risk of thyroid cancer 1-7% up to 30 years later

Thyroid Nodule Tests: Calcitonin: Small reports suggest meduallry CA mets can be prevented Cost effectiveness unclear FNA: Gold standard to evaluate thyroid nodule Adequate specimen can be obtained in 90% of patients False negative and false positive are reported to be as low as 5%

Thyroid Nodule FNA 5-8% of aspirates are diagnostic of malignancy 10-20% considered suspicious for malignancy 2-5% fail to provide adequate samples With suspicious findings 25% of patients are found to have malignancy If patients chooses, questionable biopsy can be followed with sonography every 6 months

Thyroid Nodule Thyroid Sonography Sensitive to 3 mm nodules 3-20% of nodules are found to be cystic Cystic lesions have lower incidence of malignancy than solid masses (3% vs. 10%)

Thyroid Nodule

Thank you Questions?