Hyperthyroidism, Hypothyroidism and Thyroiditis Flashcards
What is secondary thyroid disease?
Hypothalmic or pituitary disease
(this will indirectly impact the thyroid)
What is a goitre?
A swelling in the neck from an enlarged thyroid
By what other name is thyrotropin known?
Thyroid stimulating hormone
Which cells secrete TSH?
Thyrotroph cells
(anterior pituitary)
How are T3/T4 produced?
- Postive stimulus on hypothalamus
- Thyroid releasing hormone secreted
- TRH acts on anterior pituitary
- Thyroid stimulating hormone secreted
- TSH acts on thyroid
- T3/T4 produced
At which pointsin the hypothalmic-pituitary-thyroid axis can T3/T4 self regulate their release?
- Act on hypothalamus to reduce TRH release
- Act on pituitary to reduce TSH release
What are the thyroid hormone levels like in primary hypothyroidism?
Free T3/4 low
TSH high
What are the thyroid hormone levels like in primary hyperthyroidism?
Free T3/4 high
TSH low
What are the thyroid hormone levels like in secondary hypothyroidism?
Free T3/4 low
TSH low (or “normal” within the context)
What are the thyroid hormone levels like in secondary hyperthyroidism?
Free T3/4 high
TSH high (or “normal” in the context)
Hypothyroidism is the product of any disorder that results in what?
Insufficient thyroid hormone secretion
What is myxoedema?
Severe hypothyroidism
Pretibial myxoedema is a rare clinical sign of which condition?
Graves’ disease
Hypothyroidism is most common in which ethnic background?
White caucasian
Chronic thyroiditis is known by which other term?
Hashimoto’s thyroiditis
What can cause chronic goitrous thyroiditis (Hashimoto’s)?
- Iodine deficiency
- Drugs (amiodarone, lithium)
- Maternal transmission (antithyroid drugs)
- Hereditary biosynthetic defects
Non-goitrous primary hypothyroidism is known by which other term?
Atrophic thyroiditis
What may induce non-goitrous primary hypothyroidism?
- Post-ablative therapy (radioiodine, surgery)
- Post-radiotherapy (e.g. lymphoma treatment)
- Congenital developmental defect
Self-limiting primary hypothyroidism may be the result of which 3 main things?
- Withdrawal of antithyroid drugs
- Subacute thyroiditis with transient hypothyroidism
- Post-partum thyroiditis (immediately following birth)
What are some causes of secondary hypothyroidism?
- Infection
- Infiltrative
- Malignant
- Traumatic
- Congenital
- Cranial radiopathy
- Drug-induced
What is the most common cause of autoimmune hypothyroidism in the western world?
Hashimoto’s thyroiditis
How is autoimmune (Hashimoto’s) thyroiditis characterised?
- Antibodies against thyroid peroxidase (TPO)
- T cell infiltrate and inflammation
Which parts of the body are affected in hypothyroidism?
- Hair and skin
- Neurological
- Cardio
- Respiratory
- GI
- Gynae/reproductive
- Metabolic
How are the hair and skin affected in hypothyroidism?
- Coarse, sparse hair
- Dull expressionless face
- Periorbital puffiness
- Pale cool skin that feels doughy
- Vitiligo
- Hypercarotenaemia
- Pitting oedema
How is the cardiovascular system impacted by hypothyroidism?
- Reduced heart rate
- Cardiac dilatation
- Pericardial effusion
- Worsening heart failure
How are metabolic processes affected in hypothyroidism?
- Hyperlipidaemia
- Slowed, decreased appetite, weight gain
How is the GI system affected in hypothyroidism?
- Constipation
- Megacolon and intestinal obstruction
- Ascities
How is the respiratory system affected in hypothyroidism?
- Deep hoarse voice
- Macroglossia
- Obstructive sleep apnoea
What is macroglossia?
Abnormally enlarged tongue
How is the CNS affected in hypothyroidism?
- Decreased intellectual or motor activities
- Depression, psychosis
- Muscle stiffness, cramps
- Peripheral neuropathy
- Prolongation of the tendon jerks
- Carpal tunnel syndrome
- Cerebellar ataxia, encephalopathy
- Decreased visual acuity
How is the gynae/reproductive system affected in hypothyroidism?
- Menorrhagia (heavy periods)
- Oligo (reduced periods) or amenorrhoea (absent periods)
- Hyperprolactinaemia (due to increased TRH)
What may the results show for the following things in hypothyroidism?
a) Red cell size
b) Creatine kinase
c) LDL
d) Na+
e) Prolactin
a) Macrocytosis (enlarged)
b) Increased CK
c) Increased LDL
d) Decreased Na+ (hyponatraemia)
e) Increased prolactin (hyperprolactinaemia)
What are the three thyroid antibodies which ca be detected in Hashimoto’s thyroiditis (and Grave’s disease)?
- Anti-thyroid peroxidase (anti-TPO)
- Anti-thyroglobulin
- TSH receptor antibody
What may occur to a patient with hypothyroidism if restoration of metabolic rate occurs rapidly?
Cardiac arrhythmias