Subclincal Thyroid Disease and the Work-up of a Thyroid Nodule

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Subclincal Thyroid Disease and the Work-up of a
Thyroid Nodule

• Jared Bunevich MS IV
• LECOM

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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

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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)

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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)

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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

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Subclincal Hypothyroidism
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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

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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 PEPLVET was found to
  significantly improve in subclincal patients when
  treated with levothyyroxine

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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)

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Subclinical Hypothyroidism
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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

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Subclinical Hyperthyroidism
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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

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Subclinical Hyperthyroidism

• Differential Diagnosis
• Silent thyroiditis
• Steroid use
• Dopamine administration
• Pituitary dysfunction
• Early Hashimotos or Graves disease
• Multinodular goiter (particularly in the elderly)

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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

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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

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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

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Subclinical Hyperthyroidism

• Neuropsychiatic Boomer et al
• Reduced feelings of well being
• Inability to concentrate
• Feelings of fear

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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

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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,
  Hashimotos
• Radioactive iodine
• Only cost-effective if medical therapy fails x2

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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

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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

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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

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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)

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Thyroid Nodule
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Thank you

• Questions?