Transcript Subclinical Hyperthyroidism

Subclincal Thyroid
Disease and the Work-up
of a Thyroid Nodule
Jared Bunevich MS IV
LECOM
Objectives
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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
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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
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Diagnosis
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Increase serum TSH and free T4 within the normal range
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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
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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
Subclinical Hypothyroidism
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Course:
TSH may return to normal after several month
reassessment and can be attributed to:
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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
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Symptoms:
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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
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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
Subclinical Hypothyroidism
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Treatment options
Overt Hypothyroidism
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Typical Patient
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Elderly and the Patients with heart disease
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Start with Levothyroxine 25-50 ug daily and increased slowly by 25-50
ug to 75 or 100 ug
Start a lower doses and progress at smaller increments to 50 or 100 ug
or 1.6 ug/kg
Subclinical Hypothyroidism
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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
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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
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Differential Diagnosis
Silent thyroiditis
 Steroid use
 Dopamine administration
 Pituitary dysfunction
 Early Hashimoto’s or Graves disease
 Multinodular goiter (particularly in the elderly)
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Subclinical Hyperthyroidism
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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
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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
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In addition patients increased interventicualr wall
thickness
Subclinical Hyperthyroidism
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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
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Neuropsychiatic: Boomer et al
Reduced feelings of well being
 Inability to concentrate
 Feelings of fear
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Subclinical Hyperthyroidism
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Diagnostic Assessment
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TSH, T3, T4 evaluation
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Monitor for three months if indicative of subclinical
hyperthyroidism
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If TSH concentration remains suppressed a RAIU is indicated
with possible sonography
 Also, in elderly patients consider ECG, bone mineral density
exams
Subclinical Hyperthyroidism
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Treatment options
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Antithyroid medications
PTU 50-100 mg /day
 Mehtimazole 5 mg /day if not pregnant
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Surgery
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Initiate if RAIU is positive or if patient is symptomatic for 6-12
months
Non-complaint or patients who develop Garves,
Hashimoto’s
Radioactive iodine
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Only cost-effective if medical therapy fails x2
Thyroid Nodule Work-up
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Clinical Hx
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Consider
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Age
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Malignancy is higher in youth with nodules
Sex
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Less common in men but more likely to be malignant
Family history
 History of neck radiation
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0.5 Gy increases risk of thyroid cancer 1-7% up to 30 years later
Thyroid Nodule
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Tests:
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Calcitonin: Small reports suggest meduallry CA mets
can be prevented
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Cost effectiveness unclear
FNA: Gold standard to evaluate thyroid nodule
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Adequate specimen can be obtained in 90% of patients
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False negative and false positive are reported to be as low as 5%
Thyroid Nodule
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FNA
5-8% of aspirates are diagnostic of malignancy
 10-20% considered suspicious for malignancy
 2-5% fail to provide adequate samples
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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
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Thyroid Sonography
Sensitive to 3 mm nodules
 3-20% of nodules are found to be cystic
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Cystic lesions have lower incidence of malignancy than
solid masses (3% vs. 10%)
Thyroid Nodule
Thank you
Questions?