Thyroid Gland and Its Disorders
Diffuse thyroid disease - including hyper- and hypo-thyroidism
(Graves' and Hashimoto's diseases) - clinical features, causes,
investigstion and treatment
Nodular thyroid disease - including thyroid cancer - clinical
features, causes, investigations and treatment
The thyroid gland is a butterfly shaped gland, in the neck over the trachea. It consists
of a right and left lobe joined by a narrow isthmus. There is also a variable pyramidal
lobe. It weighs around 15-20 grams and there are parathyroid glands at the back.
Thyroid gland produces two hormones,
T4 – thyroxine
T3 – Triiodothyronine
Endocrine organs, including the thyroid gland are under control of the hypothalamus
pituitary axis.
So hypothalamus releases TRH, which stimulates the pituitary gland to release TSH,
which stimulates the thyroid gland to synthesise and release T3/T4.
There can then be negative feedback of TH on pituitary gland (and hypothalamus?)
We have primary problems that are an issue with the gland itself and secondary
problems that are an issue with the pituitary.
The thyroid gland mostly releases T4, but T3 is the much more active one. Therefore
T4 may be converted to T3 in the liver but also specifically in target tissues (through
, the deiodinases), because your heart will need different amount of T3 compared to
your CNS/brain etc.
The thyroid gland is made up of thyroid follicles, which themselves are composed of a
mass of colloid surrounded by follicular cells.
Follicular cells produce thyroid hormone.
There are also para-folicular cells (C-cells), that produce calcitonin which are involved
in calcium metabolism.
Colloid – Contains thyroglobulin which is a protein synthesised by the follicular cells.
Thyroglobulin contains tyrosine residues, which get combined with iodine which
allow the formation of thyroid hormones.
T4 – contains 4 iodines
T3 – contains 3 iodines
Reverse T3 – inactive
Tyrosine + Iodine = monoiodotyrosine (MIT)
Monoiodotyrosine + iodine = diiodotyrosine (DIT)
Diffuse thyroid disease - including hyper- and hypo-thyroidism
(Graves' and Hashimoto's diseases) - clinical features, causes,
investigstion and treatment
Nodular thyroid disease - including thyroid cancer - clinical
features, causes, investigations and treatment
The thyroid gland is a butterfly shaped gland, in the neck over the trachea. It consists
of a right and left lobe joined by a narrow isthmus. There is also a variable pyramidal
lobe. It weighs around 15-20 grams and there are parathyroid glands at the back.
Thyroid gland produces two hormones,
T4 – thyroxine
T3 – Triiodothyronine
Endocrine organs, including the thyroid gland are under control of the hypothalamus
pituitary axis.
So hypothalamus releases TRH, which stimulates the pituitary gland to release TSH,
which stimulates the thyroid gland to synthesise and release T3/T4.
There can then be negative feedback of TH on pituitary gland (and hypothalamus?)
We have primary problems that are an issue with the gland itself and secondary
problems that are an issue with the pituitary.
The thyroid gland mostly releases T4, but T3 is the much more active one. Therefore
T4 may be converted to T3 in the liver but also specifically in target tissues (through
, the deiodinases), because your heart will need different amount of T3 compared to
your CNS/brain etc.
The thyroid gland is made up of thyroid follicles, which themselves are composed of a
mass of colloid surrounded by follicular cells.
Follicular cells produce thyroid hormone.
There are also para-folicular cells (C-cells), that produce calcitonin which are involved
in calcium metabolism.
Colloid – Contains thyroglobulin which is a protein synthesised by the follicular cells.
Thyroglobulin contains tyrosine residues, which get combined with iodine which
allow the formation of thyroid hormones.
T4 – contains 4 iodines
T3 – contains 3 iodines
Reverse T3 – inactive
Tyrosine + Iodine = monoiodotyrosine (MIT)
Monoiodotyrosine + iodine = diiodotyrosine (DIT)
