Thyroid Diseases Flashcards
Give examples of autoimmune hypothyroidism conditions
Hashimoto’s thyroiditis
Atrophic thyroiditis
What is Graves’ disease?
Overproduction of thyroid hormones giving hyperthyroidism symptoms and sometimes Graves’ ophthalmopathy (gritty, irritated, swollen, sensitive eyes) or Grave’s dermopathy (red, thick and rough, commonly on shins)
___ antibodies may be checked in patients with a high TSH, to help establish the underlying cause. If the ___ antibodies are positive, it means the cause of hypothyroidism is an autoimmune disease (e.g. Hashimoto’s thyroiditis)
TPO (thyroid peroxidase)
________ (Tg) is produced by thyroid cells: both benign and malignant cells, helps body create, store and release thyroid hormones. After successful cancer treatment, ______ should not be detectable in blood. Detectable presence, particularly rising ______ level, may give early warning of recurrence of cancer.
thyroglobulin
P_____ t_____ happens when a woman’s thyroid becomes inflamed after having a baby. It may first cause the thyroid to be overactive. But in time it can lead to an underactive thyroid.
Postpartum thyroiditis
What % of women will get Graves’ disease autoimmune hypothyroidism?
2%
What % of women will get postpartum thyroiditis?
5%
Which 2 autoantibodies are found in almost all patients with autoimmune hypothyroidism?
Thyroglobulin and thyroid peroxidase (TPO)
Mechanism of thyroid cell destruction
Cytotoxic T cell-mediated
Thyroglobulin and TPO antibodies may cause secondary damage
What antibody causes Grave’ disease
Many thyroid stimulating antibodies (TSH receptor antibodies) leading to hyperthyroidism
What happens in Myxoedema (hypothyroidism)? :
TSBAb (blocking antibodies) bind to receptor and block TSH causing hypothyroidism
Risk factors to thyroid autoimmunity
Female
Postpartum
Genetics (HLA-DR3 genes)
Environmental factors (stress, high iodine intake, smoking)
Name some autoimmune disease associated with thyroid autoimmunity
Type 1 diabetes mellitus
Addison’s disease
Chronic active hepatitis
Rheumatoid arthritis
Graves’ disease
Pernicious anaemia
Vitiligo
What is thyroid associated ophthalmopathy?
Present in most Grave’s disease patients, swelling in extraocular muscles, likely due to autoantigen that is similar shape to thyroid autoantigen
Grave’s disease is caused by thyroid stimulating antibodies that may cross the p___
placenta
What is goitre?
Palpable and visible thyroid enlargement
True of false: goitre is endemic in iodine deficient areas?
True
What is the most common endocrine disorder?
Sporadic non-toxic goitre (8.6% prevalance), normal thyroid function.
Definition of hyperthroidism
Excess of thyroid hormone in blood due to:
1) overproduction of thyroid hormone
2) leakage of preformed thyroid hormone from thyroid
3) ingestion of excess thyroid hormone
Toxic m______ goitre and toxic adenoma can also cause hyperthyroidism
multinodular
Drug iinduced hyperthyroidism
Iodine
Amiodarone
Lithium
Radiocontrast agents (contains iodine)
Clinical features of hyperthyroidism
Weight loss
Anxiety
Tremor
Hyperphagia
Tachycardia
Heat intolerance
Sweating
Diarrhoea
Lid lag and stare
Menstrual disturbance
Specific clinical signs of Graves’
Thyroid eye disease
Pretibial myxoedema (accumulation of excess glycosaminoglycans in the dermis and subcutis of the skin)
Acropachy (digital clubbing, soft tissue swelling of the hands and feet, and periosteal new bone formation)
Adenoma specific clinical signs
Solitary nodule
Investigation of hyperthyroidism
Thyroid function test
Supporting investigation: isotope uptake scan, thryoid antibodies: TPO, Tg, TRAb
In primary hyperthyroidism, thyroid function tests would show…
increased free T4, increased free T3, suppressed TSH
In secondary hyperthyroidism, thyroid function tests would show…
Increased free T4, increased T3, inappropriately high TSH
Treatment for hyperthyroidism
Antithyroid drug (eg thionamides)
Radioiodine 131I
Surgery
Name some thionamides (antithyroid drug)
Carbimazole (most common)
Propylthiouracil (PTU)
Methimazole
How do thionamides work?
Decrease synthesis of new thyroid hormone
Alongside decreasing synthesis of new thyroid hormone, what does PTU also do?
Inhibit conversion of T4 to T3
Side effects of thionamides
Rash
Agranulocytes
Less common: arthralgia, hepatitis, neuritis, thrombocytopenia, vasculitis
What is the most serious side effect of thionamides?
Agranulocytosis (deficiency of granulocytes in the blood, causing increased vulnerability to infection)
Signs = sore throat, fever, mouth ulcers
Stop thionamides if symptoms develop
Slides 58-65
Hypothyroidism
Thyroid hormones abnormally low (3 types)
Primary (>99%) absence/dysfunction thyroid gland, mostly due to Hashimoto’s thyroiditis
Secondary/tertiary
Pituitary/ hypothalamic dysfunction
Causes of primary hypothyroidism
Hashimoto’s thyroiditis
131I therapy
Thyroidectomy
Postpartum thyroiditis
Drugs
Thyroiditides
Iodine deficiency
Thyroid hormone resistance
Causes of secondary/tertiary hypothyroidism
Pituitary disease
Hypothalamic disease
Clinical features of hypothyroidism
Fatigue
Weight gain
Cold intolerance
Constipation
Menstrual disturbance
Muscle cramps
Slow cerebration
Dry, rough skin
Periorbital oedema
Delayed muscle reflexes
Carotenaemia
oedema
Investigation of hypothyroidism
Primary hypothyroidism:
Increased TSH, usually decreased T3 and T4
Secondary/ tertiary hypothyroidism:
TSH inappropriately low for reduced T3/4 levels
Treatment for hypothyroidism
Synthetic L-thyroxine (T4)
