hyperthyroidism and thyrotoxicosis Flashcards
Thyrotoxicosis
State when tissues are exposed to excess thyroid hormone
Primary Hyperthyroidism
Free T3/T4 high
TSH low
Secondary hyperthyroidism
Free T3/T4 high TSH high (or 'normal')
Hyperthyroidism Aetiology
Excessive thyroid stimulation
- Graves disease
- Hashitoxicosis
- Thyrotropinoma
- Thyroid cancer
- Choriocarcinoma
Thyroid nodules with autonomous function
- toxic solitary nodule
- Toxic multi nodular goitre
Thyrotoxicosis Aetiology
Causes of Hyperthyroidism
- Excessive thyroid stimulation
- Thyroid nodules with autonomous function
Thyroid inflammation (thyroiditis)
- Subacute (de Quervains)
- Post partum
- Drug induced
Exogenous Thyroid Hormones
- Over treatment with levothyroxine
- Thyrotoxicosis factitia
Ectopic Thyroid tissue
- Metastatic thyroid carcinoma
- Struma Ovarii
Thyrotoxicosis Signs and Symptoms
Cardiac
- Palpitation (AF)
- Cardiac failure (very rare0
Sympathetic
- Tremor
- Sweating
CNS
- Anxiety
- nervousness
- Irritability
- sleep disturbance
GI
-frequent, loose bowel movements
Vision
- liquid retraction
- double vision (diplopia)
- Proptosis (–> Graves)
Hair and skin
- brittle, thin hair
- Rapid fingernail growth
Reproductive
- Menstrual cycle changes (lighter bleeding and less frequency)
Muscle Weakness (esp, thighs and upper arms)
metabolism
- Increased appetite
- unintentional weight loss
Thermogenesis
-Intolerance to heat
Graves Disease Aetiology & Epidemiology
Interacting susceptibility genes plus environmental factors
Younger (20-50 years)
Smoking important
Graves Disease; Laboratory Investigations
Decreased TSH
Increased fT3/T4
hypercalcaemia and increase Alk Phos.
- increased bone turnover: Osteoporosis
Leucopenia (decreased WCC)
TSH receptor antibody (TRA b)
Specific Graves Clinical Signs
pretibial Myxoedema Thyroid acropachy Smooth goitre Thyroid bruit -Associated only with large goitres
Graves Eye Disease
Graves Eye Disease
Thyroid Eye Disease
Occurs in ~20% of patients with Graves
Associated with smoking
TRAb driven pathology
Treatment
- Mild: Topical
- Severe; Steroids, surgery
Nodular Thyroid Disease Presentation
Older patients. More insidious onset
Thyroid may feel nodular Asymmetrical goitre (smooth in graves)
Nodular Thyroid Disease Investigation
Increased fT3/T4
Decreased TSH
Antibody negative.
Scintigraphy: high uptake
Thyroid Ultrasound
Thyroid storm
Crisis
- Medical Emergency
Severe hypothyroidism
Thyroid storm features
Respiratory and cardiac collapse
Hyperthermia
Exaggerated reflexes
Thyroid Storm Treatment
may require mechanical ventilation
Lugols. iodine Glucocorticoids PTU B-blocker FLuids Monitoring
Hyperthyroidism Treatment
Antithyroid drugs (ATDs)
Beta-blockers
Radioiodine
Thyroidectomy
Antithyroid Drugs (ATDs) Mechanism
Inhibition of thyroid peroxidase (TPO) thereby blocking thyroid hormone synthesis
ATD examples
Carbimazole
- 1st line (once daily dosing)
- Risk off aplasia cutis in early pregnancy
Propylthiouracil
-1st line in first trimester pregnancy
ATD Side Effects
Generally well tolerated
Allergic Type Reactions (1-5%)
Liver
- Increased risk of cholestatic jaundice
- Increased liver enzymes
- Fulminant hepatic failure
Agranulocytosis (0.1-0.5%)
- Important to warn patient verbally and in writing to STOP drug and urgent FBC checked in event of fever, oral ulcer or oropharyngeal infection
- ATDs cannot be used again
- Risk highest in first 6 weeks
beta- blockers mechanism and use
B-adrenoreceptor blockage, reduced activity of sympathetic nervous system
Propranolol is drug of choice
Useful for immediate symptomatic relief of thyrotoxic symptoms
Radioiodine
1st line treatment in
- Relapsed Graves disease
- Nodular Thyroid disease
Radioiodine contraindications
Contraindicated in pregnancy
Relatively contraindicated in active thyroid eye disease (can be used with steroid cover)
High risk of hypothyroidism in Graves
Thyroidectomy
useful if radio iodine contraindicated
Will leave a scar
Surgical/ anaesthetic risks
- recurrent laryngeal nerve palsy
- hypothyroidism
- hypoparathyroidism
