1. Thyroid Disorders:
Pitfalls in Diagnosis and
Management
Professor Steven Boyages
Specialist Services
Westmead Hospital

3. Overview
• Physiology and
pathophysiology
• Pitfalls in diagnosis
– Blood tests
– Imaging
• Pitfalls in management
– Adjusting thyroid
hormone

4. Thyroid Gland
• Regulates metabolism
• Essential for life
• Active hormone is T3
• Prohormone is T4
• Iodine essential for
normal function

5. Thyroid Physiololgy

6. Pathophysiology
• Function
– Euthyroid
– Hypothyroid
– Hyperthyroid
• Morphology
– Nodule
– Single
– Multiple
– Benign
– Malignant

7. Thyroid Function Testing
• TSH
• FT4
• FT3
• What is normal?
• 0.3 to 2.5 mIU/l

8. Subclinical hypothyroidism
• What is normal?
• Should we treat?
• When and who to
treat?
• > 2.5 MIU/l
• Positive thyroid
antibodies
• Yes, it may have impacts
on lipid, cardiac status,
and fecundity

9. Subclinical hyperthyroidism
• Low TSH
• Normal FT4
• Normal FT3
• Causes
– Illness
– Nutrition
– Psychological Illness
– Drugs
• Excess iodine
• Amiodarone
• Contrast agents
– Early nodular thyroid
disease
– Early autoimmune disease
– Thyroditis

10. Complications
• Increased risk of
tachyarrythmias
• May contribute to
increased bone
turnover
• Fatigue
• Mood disturbance

11. Adjusting thyroid hormone
• Weekly dose is more important than daily dose
• Aim for 0.3 to 2.5 mIU/l
– Increase levels by 100 mcg per week
– Do not remeasure within 6 weeks
• Aim for a low TSH or suppressed
– Thyroid cancer patients
• Use FT4 and not TSH
– In patients with pituitary disease

12. Morphology
• Imaging
– Thyroid Ultrasound
– MRI
– Non Contrast CT scan