Hyperthyroidism and Hypothyroidism Flashcards
(53 cards)
What are the definitions of hyperthyroidism, hypothyroidism and thyroiditis?
Hyperthyroidism = overactive thyroid Hypothyroidism = underactive thyroid Thyroiditis = inflammation of the thyroid caused by excess thyroid hormone
What is the difference between primary and secondary thyroid disease?
Primary - disease affecting the thyroid gland itself
Secondary - hypothalamic or pituitary disease affecting the thyroid
What are the thyroid hormones?
T3 (triiodothyronine)
T4 (thyroxine)
Is more of T3 or T4 secreted?
T4 (80%)
Describe the hypothalamic-pituitary-thyroid axis?
The hypothalamus secretes TRH (thyrotropin releasing hormone)
TRH stimulates the pituitary to secrete TSH (thyroid stimulating hormone), also called thyrotropin
TSH stimulates the thyroid to secrete T3 and T4
Excess T3 and T4 inhibit the pituitary gland and hypothalamus to stop secreting TSH and TRH
Which thyroid hormone needs to undergo an extra step, and what is that step?
T4 is converted to T3 which activates it
How are TSH levels affected in primary hyper and hypothyroidism, and why?
In primary hyperthyroidism the problem in the thyroid means too much T3 and T4 are secreted so the negative feedback effect means TSH levels are low
In primary hyperthyroidism the problem in the thyroid means not enough T3 and T4 are secreted so the negative feedback effect means TSH levels are high
What are the symptoms of thyrotoxicosis?
Brittle, thin hair Proptosis (bulging eyes) Enlarged thyroid Palpitations Tremor of fingers Soft nails Sweating Frequent, loose bowel movements Infertility Scant menstrual periods Muscle weakness Heat intolerance Weight loss Anxiety, nervousness, irritability Insomnia
What are the causes of thyrotoxicosis?
Graves' disease Hashitoxicosis Thyrotropinoma Thyroid cancer Toxic solitary thyroid nodule Toxic multi nodular goitre Thyroid inflammation (subacute, post-partum or drug-induced thyroiditis) Over-treatment with levothyroxine Metastatic thyroid carcinoma
Which causes of thyrotoxicosis are associated with hyperthyroidism?
Grave's disease Hashitoxicosis Thyrotropinoma Thyroid cancer Toxic solitary thyroid nodule Toxic multi nodular goitre
What percent of the population are affected by Graves’ disease?
Females - about 1%
Males - about 0.1%
What ages usually present with Graves’ disease?
20-50 year olds
What causes Graves’ disease?
Autoimmune - interacting susceptibility genes (70%) and environmental factors
What is the biggest risk factor for developing Graves’ disease?
Smoking
What are the results of blood tests done in Grave’s disease?
TSH - low Free T3/4 - high Hyperhalcaemia Increased alkaline phosphatase Leucopenia
What conditions are associated with Graves’ disease?
Osteoporosis
What antibody test results indicate Graves’ disease?
TSH receptor antibody (70-100%)
Anti-TPO antibody (70-80%)
What clinical signs are specific to Graves’ disease?
Pretibial myxoedema
Thyroid acropachy (clubbing)
Thyroid bruit
Graves’ eye disease
What is nodular thyroid disease?
Hyperthyroidism with a nodular-feeling asymmetrical goitre
Occurs in older patients with a more insidious onset
What will blood test results be in nodular thyroid disease?
High free T4 and T3
Low TSH
Antibody negative
High uptake on scintigraphy
What investigation is diagnostic for nodular thyroid disease?
Thyroid ultrasound
What is thyroid storm (crisis)?
Severe hyperthyroidism involving respiratory and cardiac collapse, hypothermia, exaggerated reflexes - a medical emergency
Which patients are most likely to have thyroid storm?
Hyperthyroid patients with an acute infection/illness or recent thyroid surgery
What is the treatment for thyroid storm?
Lugol’s iodine
Glucosorticoids
Propylthiouracil
Beta blockers
