Endocrine disorders Flashcards
explain Hypothalamic-pituitary axis (HPA)?
- Stimuli (drugs, stress & emotions) stimulate Hypothalamus which produce Most hormones (but not all) to produce “releasing hormones” that will go via the portal circulation to stimulate pituitary gland (initial signalling)
- So, Pituitary (the anterior part) will release 6 “trophic hormones” into bloodstream going to stimulate or inhibit other endocrine glands (Thyroid, Parathyroid, Adrenal, Pancreas, Testis and Ovary)
- Then, once Endocrine glands are stimulated by the trophic hormones, they will produce end product (to act on other cells) OR acts directly (in case of growth hormone ”somatotropin” that secreted by the pituitary stimulating endocrine gland to act directly to grow and develop the body)
define The pituitary gland and its 2 distinct parts?
Small organ sitting in the base of the brain and can control endocrine system
2 distinct parts:
- Anterior pituitary:
The hypothalamic ‘releasing hormones’ will pass via “portal circulation” from hypothalamus into anterior pituitary to stimulate it to secrete 6 trophic hormones into systemic bloodstream to act on targeted glands - Posterior pituitary:
The hypothalamic ‘releasing hormones’ will pass via “neural structures” from hypothalamus into posterior pituitary to stimulate it to secrete 2 trophic hormones (ADH & Oxytocin) into systemic bloodstream
what is Negative feedback loop?
When hypothalamus is stimulated, it will secrete a hormone that stimulates the pituitary gland which in turns will secrete a hormone to stimulate another gland to secrete a specific hormone, when this specific hormone is secreted; its presence will send signals to inhibit the hypothalamus to stop secreting more of the stimulating hormone. But again when his specific hormone secretion is stopped, the hypothalamus will be triggered once again to stimulate pituitary gland and so on. This is to control hormone production from glands due to that Hormones should be only produced in specific circumstances when needed (e.g: insulin hormone production in response to ↑ glucose meal) but after adjusting the problem, gland hormones secretion should be stopped.
define Thyroid gland?
Bi-lobed organ with isthmus, sitting in lower anterior part of the neck and larynx & close to the trachea
explain how does thyroid gland get stimulated?
and what hormones it secretes?
Stimulation:
Hypothalamus secretes TRH (Thyrotropin-releasing hormone) going to the anterior pituitary gland to stimulate it to secrete TSH (Thyroid-stimulating hormone “Thyrotropin”) going via bloodstream, stimulating Thyroid gland to secrete its hormones
Thyroid Hormones:
1) T3 “Active”
2) T4 which will be converted in the blood into T3 “Active”
→ Iodine is needed to produce these hormones
Function of thyroid hormones?
1) Increase and speed up metabolic activity (fast burning gut) and basal metabolic rate (BMR)
2) Increase HR and BP
3) Growth
thyroid conditions?
1) Goitre
2) Hypo-thyroidism
3) Hyper-thyroidism
explain Goiter disorder, and how does it relate to Derbyshire Neck syndrome?
Thyroid swelling in 1 or both sides of the thyroid and it moves during swallowing
Derbyshire Neck syndrome is caused by Iodine deficiency, and it can lead to endemic Goitre as thyroid will be swollen and enlarged due to trying to produce thyroid hormones as a response to the hypothalamus and pituitary stimulation although there is no Iodine
explain Hypo-thyroidism (definition, causes, signs and symptoms, investigations and treatment)?
Failure to form T3/T4 and Low secretion of T3/T4
Causes:
1) Iodine deficiency
2) Drugs interfere with Iodine metabolism & absorption
3) Auto-immune diseases leading to destruction of thyroid
4) Iatrogenic destruction of thyroid during thyroid procedures
5) Thyroidectomy (Thyroid removal; so can’t secrete thyroid hormones)
6) Radioactive-iodine treatment (treats hyper-thyroidism and thyroid cancer), destroying the gland’s cells
Signs & Symptoms:
EVERYTHING SLOWS DOWN:
1) Weight gain (due to the reduced and slow metabolic rate)
2) Hair and nail changes and Depression
3) Loss of appetite and energy
4) Slowing of thought
5) Low HR and BP
6) Cold intolerance
Investigations:
1) Clinical examination looking at signs and symptoms (neck nodes and swellings, HR, BP)
2) Blood tests (Thyroid function tests looking for TSH, T3 and T4 levels)
3) Imaging, Ultrasound, CT and MRI of the neck
Treatment:
1) Thyroid replacement therapy (Thyroxine/Levothyroxine tablets)
explain Hyper-thyroidism (definition, causes, signs and symptoms, investigations and treatment)?
Excess formation and secretion of T3/T4
Causes:
1) Auto-immune diseases (Graves disease) “most common”, mimicking TSH action
2) Thyroid tumour (cancer)
Signs & Symptoms:
EVERYHING WILL BE FAST!:
1) Weight loss (due to the increased and fast metabolic rate)
2) Anxiety and Mania (Psychosis)
3) Tachycardia (fast HR >100bpm) and Atrial fibrillation (Irregular fast heart rate)
4) Palpitations and Tremor (due to the increased and fast metabolic rate)
5) Heart murmur (whooshing sound due to the rapid turbulent blood flow)
6) Heat intolerance
Investigations:
1) Clinical examination looking at signs and symptoms (neck nodes and swellings, HR, BP)
2) Blood tests (Thyroid function tests looking for TSH, T3 and T4 levels)
3) Imaging, Ultrasound, CT and MRI of the neck
Treatment:
1) Surgery to remove the gland
2) Radioactive-iodine treatment but it can damage the gland, leading to Hypo-thyroidism, so pt needs life-long thyroid replacement therapy
define adrenal gland, and its distinct parts (mention hormones of each part)?
2 glands just above both kidneys (but not related to the kidneys) and having 2 regions:
- Outer cortex, producing:
* Glucocorticoids (Cortisol) -> Glucose metabolism (increase blood sugar) due to body stress
* Mineralocorticoids (Aldosterone) -> Salt and water balance
* Sex steroids (Oestrogens & Androgens) -> Masculinisation (development of sexual characteristics) - Inner medulla, producing:
* Catecholamines (Adrenaline & Noradrenaline) -> Increase Heart rate and blood pressure
how does adrenal glands get stimulated in case of Cortisol secretion?
Hypothalamus secretes CRH (Corticotrophin-releasing hormone) going to the anterior pituitary gland to stimulate it to secrete ACTH (Adreno-Corticotrophic hormone) going via bloodstream, stimulating Adrenal gland (the cortex part) to secrete Cortisol
what is Cushing’s syndrome, causes, signs and symptoms?
Cushing’s Syndrome (Hyper-adreno-corticism):
Excess cortisol secretion
Causes:
1) Iatrogenic: Long-term Steroid (Cortico-steriods) prescription
2) Cushing’s Disease
3) Other tumours secreting their own ACTH
Signs & Symptoms:
1) Diabetes (due to very increased blood glucose)
2) Central obesity, Moon face, Buffalo hump and Striae
3) Thin skin with Facial hair and Acne and Thin hair
4) Peripheral wasting and weakness
what is Adrenal insufficiency and its causes?
Adrenal insufficiency (Hypo-adreno-corticism):
Low cortisol secretion
Causes:
1) Primary Adrenal Insufficiency (Addison’s disease; Autoimmune diseases destruction of adrenal glands, so cannot produce endogenous “natural” steroids, so pts need to take exogenous steroids)
2) Secondary Adrenal Insufficiency/Suppression/Atrophy (Reduced adrenal size due to taking Exogenous steroids “Hydro-cortisone, Prednisolone” acting the same as Cortisol, affecting on feedback loop as their presence in the blood will reduce CRH and ACTH secretions “Inhibition of Hypothalamus and Pituitary”, this eventually leads to low natural Cortisol secretions from adrenal glands, so reducing in size)
So what will happen if having atrophic adrenal glands “reduced size”?
Adrenals will not respond to Stress, illness and Surgery as normally as these events need more Cortisol secretion to manage HR, BP and blood glucose and adrenals will be unable to do that, leading to Addisonian Crisis (Acute adrenal insufficiency)
Non-specific symptoms:
1) Fatigue, Malaise, Weight loss and Depression
2) Abdominal pain, Nausea and Vomiting
3) Muscle pain and Joint pain
