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

2. 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

3. 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)

4. 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 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)

5. 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

6. Subclincal Hypothyroidism

7. 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

8. 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

9. 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)

10. Subclinical Hypothyroidism

11. Subclinical Hypothyroidism
Treatment options
Overt Hypothyroidism
Typical Patient
Start with Levothyroxine ug daily and increased slowly by 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 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

12. Subclinical Hyperthyroidism

13. 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

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

15. 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

16. 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

17. 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

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

19. 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

20. Subclinical Hyperthyroidism
Treatment options
Antithyroid medications
PTU 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

21. 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

22. 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%

23. 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

24. 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%)

25. Thyroid Nodule

26. Thank you
Questions?