Clinical thyroid disease Flashcards
What will happen if hypothyroidism is severe?
- FBC (MCV (mean corpuscular volume) increased)
- Lipids (hypercholesterolaemia)
- Hyponatraemia (low sodium) due to SIADH (high secretion of antidiuretic hormone)
- Increased muscle enzymes (ALT and CK)
- Hyperprolactinaemia
What are the common tests for hypothyroidism?
○ TSH/ fT4
○ Autoantibodies: TPO (Thyroid peroxidase antibodies)
What are the common tests for hyperthyroidism?
- Thyroid peroxidase antibodies
- TSH receptor antibodies
- Review personal/ family history for concurrent autoimmune disease
What are the common presentations of hypothyroidism?
○ Weight gain
○ Lethargy
○ Heavy periods
○ Feeling cold
○ Dry skin/ hair
○ Slow reflexes
○ Constipation
○ Bradycardia
○ Goitre
○ Severe
- Puffy face
- Large tongue
- Hoarseness
- ComaWhat are the common presentations of hyperthyroidism?
- Weight loss
- Sensitive to heat
- Light periods
- Anxiety/ irritability
- More bowel movements
- Palpitations
- Sweaty palms
- Hyperreflexia/ tremor
- Thyroid eye symptoms/ signs
- Goitre
What are the common presentations for grave’s disease
- Thyroid eye disease (10%)
- Gynecomastia
- Thyroid acropathy
- Goitre
- Grave’s demopathy
What are the different types of hypothyroidism?
○ Primary (thyroid) ○ Secondary (pituitary) ○ Subclinical (compensated) ○ Acquired ○ Pituitary/ hypothalamic damage
What are the different types of hyperthyroidism
○ Primary
○ Secondary
○ Thyrotoxicosis without hyperthyroidism
○ Subclinical hyperthyroidism
What are the general hyperthyroid management strategies?
○ Surgery ○ Antithyroid drugs ○ Radioiodine ○ Beta blockers - Symptom management
Explain antithyroid drugs in more detail
- Drugs □ Carbimazole □ Propylthiouracil - Side effects □ Rash □ Agranulocytosis 1:500 - Administration □ Titration regime ® start at a high dose and then decrease the dose when stable ® 50% cure ® 30% hypothyroidism □ Blockage ® Start at a high dose and then add in thyroxine when stable ® 50% cure ® 30% hypothyroidism ® Higher side effects - Selected cases for long term low dose administration □ Elderly □ Cardiac complications □ Unwilling for radioiodine
Explain radioiodine in more detail
- Types
□ High ablative dose
® 90% cure
® 70% hypothyroidism
□ Variable calculated
® 60-90% cure
® Less hypothyroidism - Side effects
□ Cannot have contact with children or pregnant women for 4 weeks
□ It could cause eye problems (steroids)
□ For a month or two security alarms at the airport will go off
Discuss the principles of treatment of hypothyroidism
• Levothyroxine (T4) tablets
• Liothyronine (T3) doesn’t really work and a combination of T3 and T4 doesn’t work either
• Initial dose of levothyroxine is 50mcg/ day increase after 2 weeks to 100mcg
• Alter dose until TSH is normal (or fT4 is in normal range in secondary)
• After stabilisation there should be annual testing of TSH
• Compliance
• Ischemic heart disease
○ Start at lower dose 25mcg
○ Increase cautiously
○ Risk of precipitating angina
• Pregnancy
○ Most patients need an increase (35-40%) in LT4 dose
○ If they have subclinical hypothyroidism treat
○ Inadequate treatment of hypothyroidism linked with increased foetal loss and lower IQ
○ At diagnosis of pregnancy
- Increase LT4 dose by about 25% and monitor closely
- Aim to keep TSH in low normal range and FT4 in high normal range
• Postpartum thyroiditis
○ Trial withdrawal
○ Measure TFTs in 6 weeks
• Myxoedema coma
○ Very rare emergency
○ May need IV T3 (steroid)
• Subclinical hypothyroidism
○ Consider treating TSH >10
○ TSH >5 with positive thyroid antibodies
○ TSH elevated with symptoms: trial therapy of 3-4 months and continue if symptomatic improvement
○ Risk of overtreatment
- Osteopenia
- Atrial fibrillation
What are the types of thyroid cancer
- Papillary
- Follicular
- Anaplastic
- Lymphoma
- Medullary
How is thyroid cancer managed?
○ Prognosis poorer
- Age <16 or >45
- Tumour size
- Spread outside thyroid capsule and metastases
- TNM stage
○ Near total thyroidectomy
○ High dose radioiodine (ablative)
○ Long term suppression doses of thyroxine
○ Follow up
- Thyroglobulin
- Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal)
What happens in primary hypothyroidism?
- Raised TSH (thyroid secreting hormone)
- Low FT4 and FT3 (free thyroid 3 and 4)
What happens in secondary hypothyroidism?
- Low TSH
- Low FT4 and FT3
What happens in subclinical hypothyroidism?
- Raised TSH
- Normal FT4 and FT3
Explain acquired hypothyroidism
- Autoimmune thyroid disease (this is the most common in the UK)
□ Hashimotos
□ Atrophic - Iatrogenic
□ Postoperative/ post radioactive iodine
□ External RT for head and neck cancers
□ Antithyroid drugs, Amiodarone, Lithium, Interferon - Chronic iodine deficiency (commonest worldwide)
- Post subacute thyroiditis
□ Postpartum thyroiditis
What sort of pituitary/ hypothalamic damage causes hypothyroidism?
- Pituitary tumour
- Craniopharyngioma
- Post pituitary surgery or radiotherapy
- Sheehan’s syndrome (where a woman has a massive postpartum haemorrhage)
- Isolated TRH deficiency
Describe primary hyperthyroidism
- Grave’s disease
□ 70-80% of hyperthyroidism
□ Thyroid antibodies (TSH receptor antibodies) - Toxic multinodular goitre
□ Most common cause of thyrotoxicosis in the elderly
□ Characteristic goitre and absence of grave’s disease
□ Will not go into spontaneous remission - Toxic adenoma
What causes secondary hyperthyroidism?
Pituitary adenoma secreting TSH (quite rare)
Explain thyrotoxicosis without hyperthyroidism
- Destructive thyroiditis (postpartum, subacute, amiodarone induced)
□ Subacute
® Generally younger patients <50 years
® Viral trigger (e.g. enterovirus, coxsackie)
® Often painful goitre +/- fever/ myalgia; ESR increased
® May require short term steroids and NSAIDs - Excessive thyroxine administration
Explain subclinical hyperthyroidism
- TSH suppressed
- Normal free thyroid hormones
- Concerns
□ Bone: decreased bone density in postmenopausal; no clear fracture data
□ AF: 3 fold increased risk in over 60 - Treatment: consider ATD or RAI if persistent especially in the elderly or those with increased cardiac risk
Explain papillary thyroid cancer
○ Commonest
○ Multifocal, local spread to lymph nodes
○ Good prognosis
