thyroid and diabetes Flashcards
Thyroid hormones and iodine deficiency ??
Iodine is needed for production of thyroid hormone.
The body cannot make iodine has to come from diet.
iodine deficiency - don’t make enough thyroid hormone - Hypothyroidism - can cause Goitre (swelling of the thyroid gland in neck - gland becomes progressively larger to keep up with demand karger to keep up with
What period of time does thyroid stimulation increase ?
During :
Cold
Exercise
Pregnancy - due HCG -fetal development
Increases metabolism
Palpation and thyroid?
Thyroid gland should not be able to be palpated
can be palpated when it enlarges.
What amino acids is used to produce thyroid hormones
Tyrosine.
Where is Calcitonin produced ?
Thyroid C - Cells which reduces blood Ca and has opposite effect of PTH.
How does Thyroid hormone exert its action ?
T4 enters cells ——- > T4 loses iodine so converted into T3 via action of iodinase enzyme ——–> T3 enters the nucleus ——– > T3 binds to thyroid hormone receptor ——– > This stimulates gene transcription ——- > mRNA leaves nucleus to allow the synthesis of proteins .
Proteins facilitate the action of thyroid hormone e.g Brain , heart , GI Tract , basal metabolic rate etc.
How is Thyroid hormone made ?
1, Follicular cell synthesizes Thymoglobulin - protein and enzymes into colloid - Glycoprotein (nodule thingy - collects here before release)
- Iodine co-transported unto cell with Sodium
- Iodine transported into colloid
- Iodine added to Thymoglobulin to make T3 and T4 by enzymes - Thyroid perioxidase (TPO)
- Thymoglobulin taken back into cell.(with T3 and T4 attached )
- T3 and T4 separated from Thymoglobulin by intracellular enzymes.
- T3 and T4 enter into circulation.
What is the lifetime of T3 and T4?
T4 - 6-7 days - long-lasting hormone - so treatment - need to be patient - especially Hyperthyroidism - take some time for effects to be seen - don’t overdose patient.
T3 - 10 hours
What is Thyrotoxicosis?
Conditions characterized by Excess of thyroid hormone produced by the thyroid gland.
a most common form - Graves disease / diffuse toxic goiter- autoimmune.
Patients with autoimmune Hyperthyroidism are at higher risk of developing autoimmune diseases e.g type 1 diabetes, Addison’s disease, Rheumatoid arthritis. etc.
Hyperthyroidism - excess synthesis of Thyroid hormone
Thyrotoxicosis - excess circulating thyroid hormone.
Graves disease - what is it powerpoint ?
Graves disease - automimmune condition - Hyperthyroidism
T cell stimulate B cells to release TSI ( Thyroid stimulating immunoglobulin - autoantibody )
These bind to receptors of thyroid cell for 24 hours or more - strongly binds ( same receptors and TSH - which only binds for a few mins)
This leads to overproduction of T3 and T4.
TSI test - can be used to check for Graves disease
High levels of TSI auto-antibody suggest Graves disease.
(also Thyrogloblin antibodies , Thyroperoxidase antibodies )
IMPORTANT SIGNS -
- protrusion of eyes - thyroid eye diease.
- Goitre
Hashimotos disease ?
Immune system attacks your thyroid gland .
Auto reactive B cell differentiate into plasma cell which release auto antibodies which damage thyroid cells e.g apoptosis and thyroid cell death.
Blood test look for anti thyroid antibodies -
0 Thyroglobulin (Tg ) antibodies - low levels with normal function.
0 TP0 antibodies- thyroperoxidase. - enzyme that attaches iodine to thyroglobulin - antibodies are against this enzyme.
(Raised level found in almost all Hashimoto patients, raised levels can also indicate Graves disease and other automimmune thyroid diseases. )
What is sub- clinical hypothyroidism ?
early . mild form of hypothyroidism - they are experiencing symptoms of hypothyroidism.
0 TSH levels are below normal range but T3 and T4 are normal .
Treatment of thyriod storm ?
emergency
- Intravenous fluids
- Propanolol - beta blocker - need to stabilise the heart
- Hydrocortisone
oral iodine solution , carbimazole , propylthiouracil.
Hypothyroidism - low t3 - expand
Can have increased TSH , T4 but low T3 — slow conversion of T4 to t3 (deiodinase deficiency )
iodinase converts t4 to t3 by removing iodine.
excess Thyroid hormones and Diabetes ?
Excess T3 and T4 promote Hyperglycemia
(Thyroid hormones increase basal metabollic rate - due to increased gluconeogenesis, Glycogenlysis etc. )
Thyroid hormones enhance Glycogen clearence .
0 Diabetes can be missed in patients with Hyperthyroiditis.
0 Thyroid storm may be masked by hyperglycemia.
