Parathyroid And Thyroid Flashcards
Where is the parathyroid gland located?
It is located below the larynx on each side of and interior to the trachea.
What is the parathyroid gland composed of?
The right and the left loops, which are United by the isthmus.
Superior parathyroid gland
Inferior parathyroid gland
Closed follicles filled with secretary substances called COLLOID.they are lined with cuboid epithelial cells.
What is the Job of the follicular cells?
They are responsible for the trapping of iodine which they secrete alongside the thyroglobulin.
What are the parafollicular cells and what is their main function?
These are also known as c cells
-they secrete the hormone calcitonin and it is a peptide hormone that works by lowering the plasma calcium concentration and has has opposite effects to those of the PTH.
What is said about the capillaries surrounding the parathyroid gland?
There is a dense capillary network running through this and has a high blood flow compared to other tissues.
Where is the venous return?
By the thyroid vein which drains into the internal jugular veins.
What stimulates the thyroid stimulating hormone and where are they both released from?
Thyrotropine releasing hormone (TRH) secreted by the hypothalamus, stimulates the production of thyroid stimulating hormone (TSH) secreted from the anterior pituitary
What are the two main thyroid hormones?
T4(thyroxine) , 90% =inactive
T3 (triiodothyronine) ,10% =active
Where do these thyroid hormones bind to?
Bound to:
-thyroxine binding globulin (TBG) carries 70% of T4 and T3
-thyroxine binding prealbumin( TBPA) binds 10% of circulating T4 and lesser amounts of T3
-albumin, binds 15% of circulating T4 and T3
Unbound form =active
Bound form= reservoir
What is the main function of thyroid hormone?
-growth
-maturation of tissues
-cell metabolism
-heat production
-oxygen consumption
-mental development
What are the parathyroid glands?
These are small glands that are located behind the upper and lower poles of the thyroid gland
What are the main functions of the parathyroid glands?
They produce parathyroid hormone
-they regulate serum calcium by secreting calcitonin from the parafollicular cells (c cells)
Why is calcium important in our bodies?
Calcium is important in the conduction of electrical impulses in nervous and muscular systems and it is the only element that has its own regulatory system which is the parathyroid glands.
If there is a decrease in calcium in serum what happens?
There is increased PTH secretion
-it acts on the kidney, gut and the bones
-to increase serum calcium level it does this by ….
THIS LEADS TO OSTEOCLAST ACTIVATION and releasing free calcium
What is the maintenance of plasma calcium?
9-10mg/dl
-40% calcium is tightly bound to plasma proteins
-10% is combined to unionised salts
-50% is free 5mg per dl
Where is calcium absorbed?
In the small intestine
How is calcium homeostasis maintained?
The absorption of calcium from the intestine is balanced by daily calcium loss through renally excretion (0.2g per day) and through saliva and bile eliminated in the faeces (0.2g per day)
What body processes is calcium important for?
-neurotransmitter release
-muscle contractions
-blood coagulation
What is the conversion factor to convert mg/dl into mmol/l?
0.250
What’s happens if the parathyroid gland releases PTH?
It will activate the osteoclast formation where it will go on to degrade bone matrix and release calcium into the blood causing an increase in the calcium level.
What will happen if calcitonin is released from the parathyroid gland?
The parathyroid gland recognises that the calcium serum level has been risen it releases calcitonin which stimulates calcium deposition in bone and therefore is a decrease in the free calcium in serum.
What is primary hyperparathyroidism?
This means that there is a fundamental increase in the amount of PTH that’s is secreted from one or more glands
-this means there is abnormally high levels of calcium
-bone degradation leading to osteoporosis
-development of kidney stones
-begin growth of parathyroid gland
What is secondary hyperparathyroidism?
This is when there is an increase in the PTH level to chronic disease
What are signs and symptoms of hyperparathyroidism?
-fatigue
-muscle weakness
-vomiting
-hypertension
-demineralisation of bones
-development of kidney stones
-apathy (loss of movement)
What is a hypercalemic Crisis?
This is when the calcium serum levels are over 15mg/dl
This can develop into neurological, cardiovascular and renal symptoms
How do we decrease calcium levels in the body?
Give :
-IV fluids to flush the calcium out
-phosphate therapy, as the calcium is increased there is a decrease in phosphate so if we increase phosphate levels we can decrease the calcium levels
-calcitonin, to store calcium in bones
-dialysis
What is hypoparathyroidism?
This is abnormally low PTH levels, so low calcium levels
This is usually caused by damage of the thyroid or surgery of the thyroid gland
What are the signs and symptoms of hypoparathyroidism?
-neuromuscular irritability ( cramps, spasms etc)
-numbness
-tingling
-bronchospasm
What would we give for hypoparathyroidism?
Calcium gluconate at bedside 10-20ml
Iv administration for 10-20 minutes but for some patients can be hours
Vitamin B
What is the difference between T3 and T4?
T3 =active
T4=inactive
What are the major functions of the thyroid hormone?
1, increases metabolism
2.protein synthesis
3.influences growth and development in children
-mental development and attainment of sexual maturity
What happens if there is a decrease in TSH?
There is decrease in a TSH there is decrease in size of thyroid gland
What happens to the thyroid functions in hypothyroidism?
-decreased metabolic rate
-elevated cholesterol levels
-myxoedema, this is the swelling of the skin and the underlying tissue giving off a waxy consistency.
What happens to the thyroid functions in hyperthyroidism?
-increased metabolic rate and oxygen consumption
-increased use of metabolic fuels
-increased sympathetic nervous system responsiveness
-thyrotoxicosis, this is the excessive secretion and activity of the thyroid hormone
-Graves’ disease (autoimmune disease) where the body attacks your thyroid gland which causes it to become overeactive.
-goiter (enlarged thyroid gland)
-thyrotoxic crisis
What is Graves’ disease?
It is a state of hyperthyroidism and goiter
This is an autoimmune disease that means the immune system mistakes your thyroid gland as a foreign inhaler meaning that it will destroy it and make it overeactive.thyroid gland stimulates thyroid stimulating antibodies which are called thyroid stimulating immunoglobulins that act through the normal TSH receptor.
What are the signs of thyroid storm?
-very high fever
-tachycardia
-angina
-congestive failure
-agitation
-restlessness
What are the signs and symptoms of hypothyroidism?
-mental and physical slugishness
-decreased cardiac output
-bradycardia
-constipation
-decreased appetite
-cold intolerance
-coarse dry ski and hair
-weight gain
Wharton are signs and symptom,s of hyperthyroidism?
-thyroid storm
-wakefullnbess
-restlessness
-irritability
-anxiety
-tachycardia
Palpitations
-diarrhoea
Weight loss
-thin and silky skin and hair
-increased sweating
What is exophthalmos?
This is the buldging of the eyes (associated with hyperthyroidism)
-bilateral in Graves’ disease (both eyes)
-unilateral in orbital tumour (one eye)
White eye staring gaze due to the overactivity of the sympathetic nervous system. There is also a collection of lose connective tissue which adds to the buldging effect.
What do we see in regards to the eyes when a patient is suffering with hypothyroidism?
Drooping of the eyes
-large tongue
In regards to the heart what problems are seen to occur in patients that have hyperthyroidism?
-low peripheral vascular resistance
-increase heart rate ,stroke volume ,cardiac output and pulse pressure
-angina
In regards to the heart what problems are seen to occur in patients that have hypothyroidism?
-high peripheral vascular resistance
-decreased heart rate,stroke volume, cardiac out
-low output heart failure
-bradycardia
In terms of GI side effects what are seen with patients with hyperthyroidism?
-increased appetite
-increased frequency of bowel movements so diarrhoea
-hypoproteinemia
In terms of GI side effects what are seen with patients with hypothyroidism?
-decreased appetite
-decreased frequency of bowel movement
In terms of the MSK system what effects are seen with a patient who has hyperthyroidism?
-weakness and muscle fatigue
-hypercalcemia
-osteoporosis
In terms of the MSK system what effects are seen with a patient who has hypothyroidism?
Stiffness and muscle fatigue
Deep tendon reflexes
In terms of the renal system, what symptoms are seen when a person is suffering with hyperthyroidism?
-mild polyuria
-increased renal blood flow
-glomerular filtration rate increased
In terms of the renal system, what symptoms are seen when a person is suffering with hypothyroidism?
-impaired water excretion
-decreased renal blood flow
-decreased glomerular filtration
In terms of the hematopoiteic system, what symptoms are seen when a person is suffering with hyperthyroidism?
-increased erythropoietin (production of red blood cells)
-anaemia
In terms of the hematopoiteic system, what symptoms are seen when a person is suffering with hypothyroidism?
-decreased red blood cell production
-anaemia
In terms of the reproductive system, what symptoms are seen when a person is suffering with hyperthyroidism?
-menstrual irregularities
-decreased fertility
-increased gonadal steroid metabolism ( the breakdown of cells that aid the reproductive cells/hormones )
In terms of the reproductive system, what symptoms are seen when a person is suffering with hypothyroidism?
-infertility
-decreased libido
-decreased gonadal steroid metabolism
-low sperm count in males
In terms of the metabolic system, what symptoms are seen when a person is suffering with hyperthyroidism?
-increased basal metabolic rate
-negative nitrogen balance
-hyperglycaemia
-increased free fatty acids
-decreased cholesterol
-increased hormone degradation
-increased rug metabolism
-decreased warfarin requirement
-increased requirements for fats and water soluble vitamins
In terms of the metabolic system, what symptoms are seen when a person is suffering with hypothyroidism?
-decreased basal metabolic rate
-increased sensitivity
-increased cholesterol
-decreased hormone degradation
-decreased drug metabolism
-increased warfarin requirement
What is Hashimoto’s disease?
This is the auto immune destruction of the thyroid thus resulting in over time the thyroid being unable to produce enough of the thyroid hormone
A goitre is present in earlier stages and is later absent.
What else can cause hypothyroidism?
Drug induced = blocked hormone formation and a goitre is to appear
What is dyshormonogensis?
This is impaired synthesis of T4 due to enzyme deficiency
A goitre is present
What drugs can cause hypothyroidism?
-PTU( propylthiouracil)
-potassium iodide
-Carbimazole
-amiadarone
-lithium
THESE DRUGS BLOCK THE THYROID FORMATION
How can radiation cause hypothyroidism?
It causes destruction of the gland or removal
A goitre is absent and it is severe
What is congenital hypothyroidism and what is it caused by?
-iodine deficiency
-TSH receptor blocking antibodies
A goitre can be either present or not
What is secondary hypothyroidism and what causes it?
This is TSH deficiency
-pituitary or hypothalamic disease
Goitre is absent
How do we measure to diagnose thyroid disorders?
-measuring the T3,T4 and TSH levels
-resin uptake test
-assessment of thyroid autoantibodies
-radioiodine 123i
-thyroid scans
-CT and MRI scans
-biopsy of the thyroid nodules
What process must be completed in lab assessments?
Sample requirement:
-5ml of venous blood
-Blood plasma collected into a tube that contains an anticoagulant
-blood collected in a plain tube
Request card information:
-drugs and pre-exsisting non thyroid disease can affect interpretation
THESE TESTS CAN BE USED WHEN CHECKING EFFECTIVENESS OF THE DRUGS USED AS THERAPY
WHAT ARE THE TYPICAL VALUES FOR THYROID FUNCTION TESTS in sub clinical primary hyperthyroidism?
-plasma TSH reduced
-plasma FT4 and FT3 are normal
-greater risk of developing graves diseased
When should thyroid tests be carried out?
6-12 months
What can hyperthyroidism lead to?
-atrial fibilaration in elderly
-reduced bone density e.g. osteoporosis in postmeneousal women
What typical values are seen for thyroid function tests in hypothyroidism?
Increased serum TSH
Serum FT4 are partially high (inactive form of thyroxine)
Offered annual testing 7
What are the three most used therapies in the treatment of hyperthyroidism?
-anti thyroid drugs
-surgery
-radioactive iodine
What is the goal in the treatment of hyperthyroidism?
To eliminate excessive thyroid hormone production and to control the symptoms
Why are beta blockers used in the treatment of hyperthyroidism?
To decrease the signs and symptoms of:
-tachycardia
-dysrhythmias
-tremor
-agitation
E.g. propranolol (non selective)
Alongside Carbimazole
What are the unwanted effects of Levothyroxine?
The thyroid hormone can increase the heart rate and output, causing dysrhythmias and signs and symptoms of hyperthyroidism.
