clinical biochem - thyroids Flashcards
what is the histology of the thyroid
spherical sacs - follicles
follicular cells
parafollicular cells
what do follicular cells do
produce thyroid hormones
what are the examples of thyroid hormones
thyroxine - T4
Tri-iodothyronine - T3
what are the 8 stages of thyroid synthesis and release
- Trapping of iodine
- Synthesis of thyroglobin
- Oxidation of iodide
- Iodination of tyrosine
- Coupling
- Pinocytosis of colloid
- Secretion of thyroid hormones
- Transport in the blood
what are the advantages of thyroxin binding global
decease in renal excretion
increase in solubility
what are the limitations of thyroxin binding globin
unbound t3 and t4
bound receptors trigger negative feedback
what is 3 functions of the thyroid hormones
bone growth
grown and differentiation of neuronal cells
chloesterol synthesis and metabolism
what increases when there is a decrease in thyroid hormones
↑ Plasma Cholesterol
↑ Creatine Kinase
↑ Creatinine
↑ Thyroid binding globulin
what increases when there is a rise in thyroid hormones
↑ Metabolic rate
↑ Plasma Calcium
↑ Sex hormone binding globulin ↑ Angiotensin Converting Enzyme ↑ Elevated Liver Enzymes (GGT)
what parts controls t3 and t4 secretion
- hypothalamus
- anterior pituitary
- thyroid gland 1
what is the most thyroid disorder
hyperthyroidism
what causes hyperthyroidism
increased thyroid hormone release
overactive thyroid
what is graves disease
autoimmune
hyperthyroidism
what causes graves disease
antibodies to TSH receptor
stimulates T3 andT4 release -> hyperthyroidism
what are symptoms of graves disease
bulging eyes
goitre- enlargement of the thyroid gland
what are symptoms of hyperthyroidism
increased irritability
increased sweating
heat intolerance
loss weight
what is the diagnosis of graves disease
low TSH, high T4
increased iodine uptake
what is the treatment and management for hyperthyroidism
- anti-thyroid drugs
- radioactive iodine
- subtotal thyroidectomy
what does primary hyperthyroidism affect
the thyroid directly
what does secondary hyperthyroidism affect
the anterior pituitary or hypothalamus
what is hashimotos thyroiditis
autoimmune destruction of the thyroid gland
what congenital abnormalities
developmental defeats
metabolic defects
ectopic organ development
what are the clinical features of hypothyroidism
myxoedema
(swelling of skin)
what are the main biomarkers of hyperthyroidism
Thyroid stimulating hormone(TSH)
T4
what happens to TSH sonf TV in hypothyroidism
↑TSH
↓T4
