Endocrine Flashcards
What is an endocrine hormone?
blood borne and acts at distant sites
What is a paracrine hormone?
acting on adjacent cells
What is an autocrine hormone?
feedback on the same cell that secreted the hormone
What is an endocrine gland?
secretes into the blood stream (thyroid, adrenal, beta cells of the pancreas)
What is an exocrine gland?
secretes through a duct (pancreas amylase and lipase)
Do fat soluble of water soluble hormones have a longer half life?
fat soluble
Are fat soluble of water soluble hormones protein bound or unbound?
fat - protein bound
water - unbound
Where do peptides store hormones?
in secretary granules
What are the different classes of hormones?
peptides, amines, idothyronines, cholesterol derivatives and steroids
Synthesis of T3 and T4?
thyroglobulin released into colloid and acts as a base for thyroid hormone sysnthesis, the incorporation of iodine forms idothyrosines, it is conjugated and then forms T3 and T4 and stored in colloid bound to thyroglobulinm TSH stimulates the movement of colloid unto secretory cell, T4 and T3 cleaved from thyroglobulin
How do adrenocortical and gonadal steroids work?
enter call and pass to nucleus by diffusing through plasma membrane, altered to an active metabolite and bind to a cytoplasmic receptor, receptor hormone complex binds to GRE, initiating transcription of gene to mRNA, and this directs protein synthesis
How is hormone secretion controlled?
continuous basal secretion, superadded rhythms (day night cycle), release inhibiting factors, releasing factors
What is synergism?
combined effects of two hormones amplified
What is permissiveness?
a hormone needed for another’s full potential effect
Function of the thyroid hormone?
accelerates food metabolism, increases protein synthesis, stimulation of carbohydrate metabolism, enhances fat metabolism, increase in ventilation rate, increase in cardiac output and heart rate, brain development during foetal life and postnatal development, growth rate accelerated
Function of growth hormone?
stimulates production of IGF-1 to induce metabolic changes
decreases adipose, increase liver function and increase muscle, increase protein synthesis, increase lipolysis
What hormone stimulates GH?
GHRH (grehlin increased GH secretion)
What hormone inhibits GH?
somatostatin
What is acromegaly?
an overgrowth of all organ systems, bones, joints, soft tissues from excessive GH secretion after fusion of the epiphyseal plates
What is giantism?
an overgrowth of all organ systems, bones, joints, soft tissues from excessive GH secretion before fusion of the epiphyseal plates
What causes acromegaly?
benign pituitary GH producing adenoma or GHRH producing bronchial carcinoid
Symptoms of acromegaly?
ABCDEF
arthralgia, arthritis, bp raised, carpal tunnel syndrome, diabetes, enlarged organs, field defect
prognathism, interdental separation, macro glossia, spade like hands and feet, increased jaw and hand size, lower pitch of voice, headaches
Investigations for acromegaly?
monitor visual fields, raised glucose, serum phosphate, urinary calcium and serum triglycerides, MRI and CT, IGFBP-3 increased, ECG, ECHO, serum prolcatin, raised IGF-1
What is the diagnostic test for acromegaly?
glucose tolerance test
GH is inhibited by glucose so should be suppressed 2 hours after oral glucose load, if not
What is IGFBP-3?
the main binding protein for circulating IGF, and is increased in acromegaly due to increased IGF-1
Management of acromegaly?
control symptoms, normalise hormones levels and correc tumour compression
trans-sphenoidal surgery of endoscopic trans sphenoidal treatment in pituitary adenomas if non invasive macroadenoma
pegvisomant
somatostatin nalogues
dopamine agonists
radiotherapy/sterotactic radiotherapy
follow ups
How does pegvisomant treat acromegaly?
for those who don’t respond to somatostatin, suppressed IGF-1 levels - does not affect tumour size
How does somatostatin analogues treat acromegaly?
inhibit GH secretion
side effect of long term dopamine agonists for acromegaly?
cardiac fibrosis - need regualr ECHO
Why is stereotactic radiotherapy better than radiotherapy in acromegaly?
more accurate for tumour location and irradiation and is less radiation to normal brin tissue
Complications of acromegaly?
hypertension, cardiac faiure, diabetes, obsturctive sleep apnoea, increased colonic polyp risk, post surgery hypopituitarism, DI, CSF rhinorrhoea, infection, hyperprolactinaemia, hormone deficiencies, gestational diabetes, gravid hypertension
Prognosis of acromegaly?
2-3x increased mortality, prediction of survival is based of the post treatment GH conc, untreated lead to death by CV disease or cancer
What are carcinoid tumours?
slow growing tumours that originate in cells of the diffuse neuroendocrine system (enterochromaffin cells)
Where do carcinoid tumours usually occur?
gastro entero pancreatic tumours, in the appendix, ileum, rectum, bronchi of lung
What condition is carcinoid tumours related to?
carcinoid syndrome
Symptoms of carcinoid tumours?
pain, weight loss, appendicitis, intussception, obstruction, RUQ pain, bradykinin, tachykinin, subsatnce P, VIP, gastrin, insuline, glucagon, ACTH, parathyroid and thyroid hormone secretion
What is carcinoid syndrome?
increased release of 5-hydroxytryptamine, prostagladins, kinins, substance P, somatostatin, corticotropin and neuron specific enolase into the peripheral circulation, secretion depends on tumour location and metastases
Presentation of carcinoid syndrome?
bronchoconstriction, paroxysmal flushing in upper body and post alcohol, coffee, food or drugs, diarrhea, abdo pain, palpitations, increased peptic ulcer risk, changes in mental state
What is the common size of a carcinoid syndrome?
1-2cm, the bigger the more likely for metastases
Investigations of carcinoid syndrome?
plasma chromogranin reflects tumour mass
24hr urinary 5-hydroxyindoleacetic acid, >25mg is diagnostic (but can be changed by other drugs and food)
pentagastrin test
gastric US and endoscopy, CT, MRI, laparotomy, scintigraphic imagaing with labelled somatostatin to find site
somatostatin SPECT
Complications of carcinoid tumours?
MEN1, appendicitus, intussception, bowel obstruction, metastatic spread
Management of carcinoid tumour and syndrome?
avoid precipitating factors, chemo e.g. doxorubicin, external beam radiotherapy, chemoembolisation, liver transplant, octreotide (somatostatin analogue) to block release of tumour mediators, loperamide for diarrhea, IFN-a, resect tumours, bebulking, radiofrequency ablation, PPI do prevent ulceration
What is carcinoid crisis?
when tumour outgrows its riction, altered mental state, hyperglyaemiablood supply or handled too much during surgery so that vasoactive mediators flow out, causing life threatening vasodilations, hypotension, tachycardia, bronchoconst
Treatment for carcinoid crisis?
octrotidem supportive measure, fluid balance managment
Prognosis of carcinoid crisis?
5-8years survival, 3 if metasatases, prognosis depends on site
What is hypothyroidism?
decreased thyroid hormone production, causing a slow down in body’s functions
Symptoms of hypothyroidism?
bradycardia, reflexes relax slowly/mentally slowing, aches, ataxia, dry skin and hair, fatigues, drowsy, cold intolerance, ascities, round puffy face, defeated demeanour, irregular/heavy periods, hoarse voice, carpal tunnel syndrome, weight gain, constripation, fluid retention, infetility, loss of libido, memory loss, confusion, goitre
What are the complications of hypothyroidism in pregnancy?
pre eclampsia, anaemia, premature labour, low birth weight, still birth, serious blleding post birth, hypothryoid coma (myxoedema coma)
How common is hypothyroidism?
0.1-0.2% of pop., increased risk with age and in women
Causes of hypothyroidism?
AUTOIMMUNE - attack thyroid gland, block binding of TSH to receptor (hashimotos if a goitre is formed)
surgery, radioactive treatment iron deficiency, medicine side effects, thyroiditis, pituitary gland problem, congenital (thyroid aplasia/dysplasia)
Risk factors for autoimmune hypothyroidism?
FH, downs, turner syndrome, enlarged thyroid, Graves disease, thyroiditis post birth, autoimmune conditions
Diagnosis of hypothyroidism?`
raised TSH, low thyroxine, thyroid antibodies, anaemia, hyperlipidaemia, hyponatraemia, incresed serum creatinine kinase levels, associated myopathy
What is subclinical hypothyroidism?
raised TSH, normal thyroxine, but thyroid glands need extra stimulation to make the required thyroxine needed, this increases hypothyroidism risk
Treatment of hypothyroidism?
lifelong levothyroxine, start low dose (esppecially in elderly) and increase dose
check TSH once a year for adjustment, which is also needed in weight gain and pregnancy
Complications of levothryoxine?
angina pain worsens, hyperthyroidism
How dose levothyroxine treat hypothyroidism?
replaces thyroxine production and normalises serum TSH concentrations
What is myxoedema coma?
severe hypothyroidism with confusion, coma, hypothermia, cardiac failure, hypoventilation, hypoglycaemia and hyponatraemia, common in elderly
Treatment of myxoedema coma?
oral T3, o2, gradual rewarming, hydrocortisone, glucose in fusion, supportive managment, thyroid diet by changing iodine in food into thyroid hormones
What is borderline hypothyroidism?
slight increased serum TSH, normal T4, due to early phase chronic autoimmune thyroiditis so 2-4% will develop overt hypothyroidism, treat with levothyroxine
What is Hashimoto’s disease?
autoimmune hypothyroidism with a goitre
Examples of thyroid diet foods?
protein, green leafy vegetables, fish, iodized salt, eggs, seaweed, avoid alcohol
Cause of Hashimoto’s disease?
iodine, medications, infection, smoking, stress
goitre associated with HLA-DR5 causing lymphatic and plasma cell infiltration, formation of lymphoid molecules from follicular hyperplasia, and damage to follicular basement membrane
In who is Hashimoto’s disease most common?
women aged 60-70
Symptoms of Hashimoto’s disease?
rapidly enlarged thyroid gland, dyspnoea, dysphagia, mild neck pain and tenderness, increase in size, thyrotoxicosis, hyperlipidaemia, fatigue, forgetfullness, myxoedema, feeling cold, weight gain, depression, poor memory
Investigations of Hashimoto’s disease?
low T3 and T4, high thyroid antibodies (anti-TPO and anti-Tg) and TSH, damaged thyroid cells, increase lymphocytes and plasma cells, thyroid parenchyma atrophy, follicular hyperplasia, lymphoid follicles, radioactive iodine uptake for hot or cold classification
Whats the difference between a hot and cold thyroid nodule?
cold has higher malignancy risk and needs a fine needle aspiration biopsy
Treatment of Hashimoto’s disease?
levothyroxine sodium to restore clinically and biochemically euthyroid state, surgery if large goitre or cosmetic reasons
Complications of Hashimoto’s disease?
over replacement can cuase bone loss and increased heart rate, hyperlipidaemia if untreatment, Hashimoto’s encephalopathy, myxoedema coma
Prognosis of Hashimoto’s disease?
good and most achieve normal thyroid levels
What is hyperthyroidism?
raised thyroid level from overactive thyroid gland
Causes of hyperthyroidism?
grave’s disease (most common), thyroid nodules, De Quervains thyroiditis, postpartum thyroiditis
What is De Quervains thyroiditis?
acute inflammation of the gland from viral infection, presenting with fever, maliase, goitre and neck pain, treated with aspirin
Symptoms of hyperthyroidism?
restless, nervous, emotional, irritable, poor sleeping, hand tremor, losing weight, increased appetite, palpitations, sweating, heat intolerance, increased thirst, diarrhoea, sob, hair thinning, irregular and light periods, tiredness, muscle weakess, neck goitree, exophthalmos, graves dermopathy
Complications of hyperthyroidism?
atrial fibrillation, cardio myopathy angina, heart failure, pregnancy complications, osteoporiosis
How common is hyperthyroidism?
10x more common in women, 20-40years
What does hyperthyroidism show in investigations?
high T4, high T3 in graves, suppressed TSH, thyroid ultrasound, positive microsomal and thyroglobulin antibodies, isotope scan to classify thyroid nodules, fine needle aspiration to exclude malignancy
Treatment of hyperthyroidism?
anti thyroid medications e.g. carbimazole to reduce thyroxine production, high dose then reduce
radioactive iodine drink to destroy thyroid tissue
regular bloods for thyroxine level check
remove part of thyroid gland
treat eye problems: artificial tears, sunglasses, eye protectors during sleep, surgery, radiation treatment, steroid tablets, stop smoking
BBs for first few weeks of treatment and reduces symptoms of tremor, palpitations, sweating, angitation and anxiety
Side effect of carbimazole?
agranulocytosis with fever, sore throat and mouth ulcers (propylthiouracil is better if pregnant)
Precautions during radioactive iodine treatment?
do not get pregnant for 6 months after, no breastfeeding, limit close contact with babies, children, pregnant women and pets, sleep alone, stay more than an arms length away from other people, avoid going places in close proximity to people, take time off work
Symptoms of ophthalmic Grave’s disease?
bilateral eye involvement, pressure and pain in one eye, a gritty sensation, reduced vision, photophobia, exophthalmos and opthalmoplegia, MRI shows enlarged muscle and oedema
What is exophthalmos and opthalmoplegia?
retro orbital inflammation, causing eye popping, worse in smokers
Treatment of ophthalmic Grave’s disease?
correct thyroid dysfunction, hyperthryoidism, smoking cessation, artificial tears, high dose systemic steroids to reduce inflammation, surgery to partially sew eyelids together to protect cornea, corrective eye muscle surgery
Triggers of ophthalmic Grave’s disease?
stress, infection, childbirth, hyperthyroid
Pathophysiology of ophthalmic Grave’s disease?
IgG autoantibodies bind to and activate G protein coupled thyrotropin receptors cyasing smooth thyroid enlargement, increased hormone production and react with orbital autoantigen, leading to catecholamine sensitivity of the levator palpebrae superioris causing lid retraction and lid lag. T lymphocytes react with antigens and cause retro orbital inflammation. Swelling and oedema of the extraocular muscles leading to movement limitation and proptosis, increasing pressure on optic nerve, leading to atrophy
How common is thyroid cancer?
1% of all malignancies, incidence is increasing, most common malignancy of endocrine system
Symptoms of thyroid cancer?
lymph node metastases, increased thyroid nodule size which is hard and irregular, enlarged lymph node
What are different types of thyroid cancer?
papillary, follicular, medullary, thyroid lymphoma, Hurthle cell, anaplastic thyroid
What is the most common thyroid cancer and in who is it most common?
papillary - women aged 35-40
What is the spread and prognosis of papillary and follicular thyroid cancer like?
spreads locally to neck, compressing trachea and recurrent laryngeal nerve, metastases most often in lung and bone
What causes follicular thyroid cancer?
areas of low iodine
In who is follicular thyroid cancer most common?
women 30-30years
Where does medullary thyroid cancer arise from?
parafollicular cells due to their malignancy making them produce carcinoembryonic antigen and calcitonin
mainly autosomal dominant inherited
Who gets thyroid lymphomas?
women aged 50 with Hashimoto’s
Symptoms of thyroid lymphoma?
dyspnoea, dysphagia, non Hodgkin’s,
Treatment of hurthle cell carcinoma?
surgery, postoperative radioative iodine 131, levotyroxine, external radiotherapy
What kind of thyroid cancers are more aggressive ?
medullar and anaplastic
Where do anaplastic thyroid cancers arise from?
follicular cells - normally from a pre existing, well differentiated thyroid tumour which has undergone additional mutational events
Risk factors of thyroid cancer?
exposure to ionising radiation, history/family history of thyroid problems, mutation in RET proto oncogenes which causes MEN2 as well, MEN1/2, Cowden’s syndrome, familial adenomatous polyposis, obesity
TNM staging?
1 - no lymph node spread or metastases, 45
3 - >4cm but contained in thyroid, or localised tumour with spread to lymphs
4a - spread to nearby structure, or localised with distant lymph node spread
4b - spread beyond nearby structures
4c - metastases
Presentation of thyroid cancer?
thyroid nodule, hard and fixed nodules suggest malignancy more, usually non tender on palpitation, firm cervical masses suggest regional node mestastases, vocal cord paralysis suggests recurrent laryngeal nerve involvement
Investigations of thyroid cancer?
TFTs, serum thyroglobin, serum calcitonin, thyroid US, fine needle aspiration cytology if >1cm or suspected malignancy (distinguishes between benign and malignant), radionuclide imaging with 123 iodine uptake studies, Gallium 67 Ga for thyroid lymphoma diagnosis, Ct and MRI for metastatic spread
Treatment of thyroid cancer?
total thyroidectomy, may need intraoperative nerve monitoring for the laryngeal nerves, radioiodine remnant ablation and therapy, adjuvant external beam radiotherapy, targeted multikinase inhibitor (sorafenib), surgery, iodine 131 for microscopic residuals, effective thyroid ablation with TSH stimulation so need extra administration
Complications of thyroid cancer?
laryngeal nerve palsy, hypoparathyroidism, nerve damage
What is Cushing’s syndrome?
increased glucocorticoid in the body
How common is Cushing’s syndrome?
5/1 million a year develop ot, main women 20-50
Functions of cortisol?
regulate BP, regulate immune system, balance insulin effect, help stress response, bone formation inhibition, decreases immune function, increase gluconeogenesis, lipolysis and proteolysis
Causes of Cushing’s syndrome?
long term steroid medication e.g. prednisolone, pituitary adenoma (Cushing’s disease) which increases ACTH, adrenal hyperplasia, ectopic ACTH production (lung cancers, MEN1), alcohol, depression
Cushing’s syndrome symptoms?
obesity, PLETHORIC complexion, moon face, facial puffiness and REDNESS, diabtes, facial hair in women, hypertension, thin EASILY BRUISED skin, STRIAE, tiredness, ache and pains, mood swings, loss of libuido, irregular periods, osteoporosis, ankle oedema, excess thirst, increased susceptibility of infections (children tend to be obese and short), PROXIMAL MUSCLE WEAKNESS