Week 23 - Hyperparathyroidism, hypothyroid, thyroid eye disease and thyrotoxicosis Flashcards
in what cases is hyperparathyroidism most clinically significant
in cases of chronic kidney disease
what are the PTH and calcium levels in primary hyperparathyroidism
PTH - normal
Calcium - high
what are the causes of primary hyperparathyroidism
tumour of the parathyroid gland (rare)
what are the PTH and calcium levels in secondary hyperparathyroidism
PTH - high
calcium - low
what are the causes of secondary hyperparathyroidism
a low level of calcium induces the parathyroid gland to produce large amounts of PTH
low levels of calcium are also commonly due to chronic renal failure
can also be caused by insuddicient vitamin D, insufficient calcium in the diet, excessive magnesium in the diet
what are the PTH and calcium levels in tertiary hyperparathyroidism
PTH - high
calcium - high
what are the causes of teritiary hyperparathyroidism
basically occurs after years of secondary hyperparathyroidism, after the secondary cause has been resolved
the parathyroid gland has been used to producing such high levels of PTH for so long, it basically just broken and secretes high levels of PTH even though levels of calcium are now responsive to PTH.
there is hyperplasia of the glands, and loss of response to calcium
what does hypothyroid refer to
insufficient thyroid hormones - T3, T4
what is primary hypothyroidism
where the thyroid behaves abnormally and produces inadequate thyroid hormones. negative feedback is absent, resulting in increased production of TSH
what are the TSH and T3,T4 levels in primary hypothyroidism
TSH is raised, T3,T4 are low
what is secondary hypothyroidism
where the pituitary gland behaves abnormally and produces inadequate TSH
this results in under-stimulation of the thyroid and insufficient T3,T4 levels
what are the levels of TSH, T3,T4 in secondary hypothyroidism
are ALL low
what is the most common cause of hypothyroidism
Hashimoto’s thyroiditis
what is hashimotos
an autoimmune condition causing inflammation of the thyroid gland.
what antibodies is Hashimoto’s associated with
anti-thyroid peroxidase (anti-TPO) antibodies and anti-thyroglobulin (anti-Tg) antibodies.
what is the most common cause of hypothyroidism in the developing world
iodine deficiency
what treatments for hyperthyroidism can cause hypothyroidism
Carbimazole
Propylthiouracil
Radioactive iodine
Thyroid surgery
what does amiodarone interfere with
thyroid hormone production and metabolism, usually causing hypothyroidism but can also cause thyrotoxicosis.
what causes a goitre in hypothyroidism
iodine deficiency
what is the mainstay of treatment of hypothyroidism
levothyroixine
synthetic version of T4 and metabolises to T3 in the body
how is the dosage of levothyroxine managed
the dose is titrated based on the TSH level, initially every 4 weeks
what is the synthetic version of T3 that is very rarely used when leveothyroixine is not tolerated
Liothyronine sodium
what is thyroid eye disease typically associated with the signs of
Grave’s disease - goitre, acropathy, hyperthyroidism and pretibial myxodema
what are the clinical features of thyroid eye disease
Swelling of the eyelids
Oedema (chemosis) and engorgement of vessels of conjunctiva
Exposure of the cornea (loss of blink, apparent lid retraction)
Pronounced exophthalmos (if absent because tight orbital septum may restrain contents and lead to raised intraorbital pressure and optic nerve compression)
Restricted eye movements (infiltration of muscles by inflammatory cells, inflammation, oedema and fibrosis)
Optic neuropathy (fundal vascular congestion, swelling or atrophy of disc)
what is the management of thyroid eye disease
Includes excluding or treating thyroid dysfunction, smoking cessation and artificial tears/ointments
o Lid retraction can be reduced by guanethidine drops (relax smooth muscle)
o If corneal exposure threatens sight, tarsoraphy performed.
o In serious disease with corneal problems or pressure on CN II: high dose steroids, surgical orbital decompression and radiotherapy.
what kind of tremor is seen in thyrotoxicosis
fine tremor
what is a thyrotoxic storm
severe acute presentation of thyrotoxicosis
what are the features of thyrotoxic storm
A marked fever (>38.5’)
Seizures
Vomiting
Diarrhoea
Jaundice
Death – can be caused by arrhythmias, heart failure or hyperthermia.
what is the treatment of thyrotoxic storm
Treatment should be started as soon as possible – and patients should be given propanolol, antithyroid drugs, potassium iodide (to reduce vascular flow to the gland) and corticosteroids.
