Endocrine Flashcards
What is endocrinology?
Study of endocrine glands and their secretions: hormones
What glands make up the endocrine system?
- Pituitary
- Throid
- Adrenal
- Pancreas
- Ovaries/Testes
What role does the pituitary gland have in homeostasis?
the master gland
extensive influence over other organs
linked to hypothalamus (which stimulates and inhibits pituitary hormones)
responsible for making hormones to stimulate organs to act
What does hypothalamus drive at birth?
Hunger Thirst Temperature Anger Fatigue
What is embryonic development of pituitary?
Develops around 3 weeks from 2 places - outpocketing of oral ectoderm and extension of neuroectoderm from diencephalon.
Around 8 weeks gestation the infundibulum grows downwards to develop into posterior lobe.
10 weeks you can start to detect growth hormone
What does the pituitary gland produce?
Anterior:
Prolactin Leutinizing/follicle stimulating hormone Adrenocorticotropic hormone Growth hormone Thyroid stimulating hormone
Posterior:
Antidiuretic hormone
Oxytocin (labour and lactation)
What issues can you have with the hormones?
Deficiency
Excess
resistance (a block to the action)
What congenital defects of the pituitary gland can you get?
Septo-optic dysplasia. (affects midline).
What is septa-optic dysplasia?
Optic nerve hypoplasia
Midline brain abnormalities
Hypopituitarism (lacking in all hormones)
What acquired disorders of pituitary/hypothalamus can you get?
Neoplastic:
- Craniophayngioma
- Optic glioma
- Astrocytoma
- Germ cell tumour
Inflammatory:
- Meningitis
- Autoimmune hypophysillis
- Landerhans cell histiocytosis
Trauma
Cranial Irradiation
What is hypopituitarism?
Reduction of all hormones
What are signs and symptoms of hypopituitarism?
Growth Hormone changes: Hypoglycaemia in infancy , growth failure in childhood
ACTH changes cause:
- hypoglycaemia
- jaundice
- hypotension
LH changes cause:
- micropenis
- Failure of puberty
TSH changes cause:
- jaundice
- poor growth
- tiredness, dry skin, hair loss
ADH changes:
- Cranial diabetes insipidus
What are treatments for hypopituitarism?
Human growth hormone - subset injections (no oral option)
Hydrocortisone
Testosterone injections
Levothroxine
What are 4 stages of growth?
Foetal
Infancy
Childhood
Puberty
what is grown in infancy most dependent upon?
Nutrition
What is average rate of growth in infancy?
25cm/year
What is growth in childhood most dependent on?
GH/IGF axis
What is rate of growth in childhood?
4-8cm/year
What is growth in puberty most dependent on?
Sex steroids and GH
What is rate of growth in puberty?
6-10cm/year
What are main hormones involved in growth?
Growth hormone
Insulin-like growth factor
Thyroid hormone
what medication can influence growth?
Asthma Sickle Cell Arthritis IBD Chronic Heart Disease CF Renal insufficiency
Basically steroids
What factors influence puberty?
Genetic background
Environment
General health of child
What aspects of general health influence puberty?
Adequate nutrition
obesity (increased BMI=early puberty)
Emotional and behaviours difficulties
Chronic disease
How does environment affect puberty?
Difficult to prove
Phytoestrogens (from carrots coffee etc)
Pesticides/herbicides (in Florida noted)
BPA (baby feeding botles/plastics)
What genetic factors can affect puberty?
family history
siblings pubertal milestones
FSH receptor
What is a prader orchidometer?
Beads to measure testicule volume in mls.
Main points: 4mls - puberty onset
10mls - start of adolescent growth spurt
12mls - peak heigh velocity (growing at fastest rate).
Up to 20mls.
When does menarche occur compared to height velocity?
After growth spurt - will have stopped growing.
When does facial hair/shaving occur compared to height velocity?
After growth spurt/stopped growing.
what is precocious puberty?
Early puberty.
True = early activation of hypothalamic-pituitary-gonandal axis
Pseudo = sex steroids secreted without activation of axis
What are some causes of true precocious puberty?
Organic CNS disruption: Tumours of hypothalamic-pituitary region. -Head Injury -Meningitis -Neurofibromatosis - Cerebral Palsy - Hydrocephalus
Cranial Surgery or Radiotherapy
What are some causes of pseudo-precocious puberty?
Sex Steroids from adrenal:
- Congenital adrenal hyperplasia
- Adrenal tumour
- Premature adrenarche (release of androgens)
- Cushing’s syndrome
Sex steroids from gonad: - Ovarian tumour McCune-Ablright Syndrome -Testotoxicosis -HCG secreting germ cell tumours
Exposure to exogenous steroids
What does Tanner staging mean in growth?
A2 G4 P3 (2/2)
A=axillary hair
G=genitalial
P=pubic hair
final = testicular volume.
Causes of delayed puberty?
Constitutional Delay of growth and puberty
Chronic disease
Central causes: Tumour/Irradiation/trauma
gonadotropin deficiency
Peripheral causes:
- Testicular damage
- Gonandal dysgenesis
- Chemo
What is treatment of delayed puberty?
Testosterone injections/gel
LH/FSH injections
What controls fluid in the body normally?
Hypothalamic centres - regulates thirst
It stimulates intake of free water and stimulaters ADH release
What is ADH
Anti Diuretic Hormone
Where does anti diuretic hormone made?
Made by hypothalamus
Stored in pituitary gland
What action does ADH have?
Stimulates the distal and collecting tubules of the kidneys - this increases reabsorption of the free water into cardiovascular system.
What is plasma osmolality?
The concentration of all chemical particles in the fluid part of the blood
What is normal level for plasma osmolality?
285-295mOsm/L
What is urine osmolality?
Number of dissolved particles per unit of water in urine.
What is normal level for urine osmolality?
500-800mOsm/kg water
Large value = concentrated urine.
What is diabetes insipidus?
Not related to sugars.
Acute or chronic condition
Inadequate secretion of ADH from the posterior pituitary gland (CranialDI)
Insufficient renal response to adequate levels of ADH (Nephrogenic DI)
Both result in the kidneys making a lot of urine.
What are causes of cranial diabetes insipidius?
Cerebral malformations (eg SOD)
Acquired disease eg surgery
Familial - genetic mutation.
What is presentation of diabetes insipidus?
Polyuria
Polydipsia (excess thirst)
Can also be constipation] Fever Vomiting Loss of weigh FTT Dehydration (need U&Es as common presentation)
What investigations are done for diabetes insipisdus?
Habitual excessive drinking - when parents stop flavoured drinks but water still available then will the child still drink lots.
If they do then will do water deprivation test.
Drug DDAVP (ADH equivalent) given. If fails to concentrate urine then implies it is nephrogenic.
Where is the thyroid gland?
In the neck, surrounding the trachea.
What do the thyroid hormones effect?
Growth
Neurological development
Metabolism
Cardiovascular function
What is embryology development of thyroid gland?
First endocrine gland to develop.
24 days - it descends but still attached to Tongue.
Descends to final position about 7 weeks.
What 2 hormones does thyroid produce?
Thyroxine T4
Tri-iodothryonine T3
Both act on pituitary
What is diagnostic tests for congenital hypothyroidism?
All babies screened in first 5 days of life - the Guthrie Test
What are symptoms of congenital hypothyroidism?
Sleepiness Poor feeding Constipation Goitre Oedema Jaundice
What is treatment for congenital hypothyroidism?
Thryoxine tables
What is occurrence of congenital hypothyroidism?
1 in 4000 births
What could causes of congenital hypothyroidism?
85% dysgenesis: Genesis/hypoplasia/ectopic
Synthetic defects: TSH deficiently, T4 synthesis
Maternal disease
T21
What is acquired hypothyroidism?
Usually autoimmune - Hashimotos thyroiditis
What are symptoms of acquired hypothyroidism?
Tireness Poor appetite Weight gain Lethargy Delayed Puberty Goitre Bradycardia Cold pasty skin
What is treatment for acquired hypothyroidism?
Levothroxine
What is hyperthyroidism?
Graves disease - autoimmune
What are symptoms of acquired hyperthyroidism?
Anxiety Increased appeptite Weight loss Heat intolerance Sleep disturbance Goitre Tachycarida Sweating Tremor
How do you treat acquired hyperthyroidism?
Anti-thyroid drugs.
Carbimazole
What is neonatal thyrotoxicosis?
Type of hyperthyroidism in babies.
Caused by trans-placental transfer of maternal TSH receptor antibodies
Stimulates the neonatal thyroid gland.
What are signs and symptoms?
All normally dissipate when start treatment:
Goitre
Tachycardia
Cardiac failure.
Jitters
What drugs would be given for neonatal thyrotoxicosis?
Carbimazole
Propanalol for jitters
prednisolone for eye disease
chloral hydrate to calm
What hormones does adrenal gland get involved with?
Sugar Salt Sex
Glucocorticoids
Mineralcorticoids
Androgens
Different layers of adrenal gland make different hormones
What is embryology development of adrenal gland?
Cortex and medulla made from different cell types.
Important by week 30 to mature the embryo
Which adrenal layers produce which hormones?
Cortex - Zone Glomerulosa:
Mineralocorticoids. Aldosterone
Cortex - Zone Fasciculata: Glucocorticoids - Cortisol
Cortex - Zone Reticularis - sex steroids/androgens.
Medulla - Catecholamines - adrenaline/noradrenaline/dopamine.
What does cortisol do in the body?
body’s natural steroid
Helps with blood sugar level (stimulates glucose production by freeing up ingredients in storage)
Helps body deal with stress (anti-inflammatory)
Helps to control BP and blood circulation
What happens with hypo secretion of adrenal cortex?
Addisons disease
Adrenal insufficiency.
What are symtpoms of Addison’s disease?
Hyposecretion of adrenal gland (glucocorticoids/mineralcorticoids)
Fatigue Muscle Weakness Anorexia Hypotension Darkening of skin Joint and muscle pain
What happens in hyper secretion of adrenal cortex?
Increased levels of cortisol in body - it is Cushing’s syndrome
What are symptoms of Cushing’s syndrome?
Hypersecretion of cortisol.
Increased weight Central truncal obesity Acne Thin Skin Moon Face Buffalo hump
What happens with adrenal medulla hypo secretion?
Not too much as other parts of body can produce adrenaline etc.
What are 3 main clinical adrenal examples?
Cushings - children on steroids. Glucocorticoid excess
Addision’s disease - generally in older child. Gluococoritoid insufficiency
Congenital adrenal hyperplasia - enzyme defect of steroid synthesis.
What is Addisonian crisis?
Adrenal glands don’t work
Low cortisol
Leads to liver function decrease and stomach digestive enzyme decrease.
Leads to low sugar (liver) and vomiting/cramps etc
Lead to extremely low sugar
Low fluid volume.
Adrenal gland also causes low aldosterone Causes kidney to loose wate rand sodium Makes heart irregular Low fluid volume Low blood pressure Shock
The 2 combined = death
What is congenital adrenal hyperplasia?
Inherited disorder of adrenal glands
Enzyme defect of steroid synthesis
When one of the enzymes involved is malfunctioning so cortisol production is impaired.
Results in cortisol deficiently
Excess pituitary ACTH secretion (pituitary senses not enough cortisol so sends more ACTH to compensate)
Adrenal gland hyperplasia (gland becomes thickened)
What is most common type of congenital adrenal hyperplasia called?
21-hydroxlyase deficiency “salt-wasting”
Deficiency in apfersterone and cortisol but male hormone still produced.
what are issues for boys with congenital adrenal hyperplasia?
Severe (salt wasting) :
Baby looks normal at birht
1-2 weeks old - poor feeding, vomiting, wt loss
U&Es: Na<115
Mild: Presents later 2-4yrs Tall stature Penis enlargement and pubic hair, Due to excessive male hormone
What are issues for girls with congenital adrenal hyperplasia?
Severe:
Baby had excessive male hormone in utero
Genetalia will look like boy - may need karotype to determine sex.
Internal structures still same, may need surgery for outer structures
Mild:
Too much male hormone.
Tall stature
Pubic hair
Enlarged clitioris
What needs to happen with a child with adrenal hyperplasia is ill?
Need to double the amount of hydrocortisone until well
In an emergency (very unwell) then have emergency hydrocortisone injection and/or glucagel. Then ambulance.
What are differences of sex development?
Congenital conditions in which development of chromosomal, gonadal or anatomic sex is atypical
What are types of differences of sex development?
True genital ambiguity (e.g. CAH girls) Genital anomalies (including hypospadia)
46XY DSD - under virilised male
46XX DSD - over virilised female.
What is diabetes mellitus?
Type 1 diabetes - mellitus meaning sweet tasting urine.
What is occurrence of diabetes mellitus?
1 in 400-500 children and adolescents
What causes diabetes mellitus?
Autoimmune destruction of beta cells in islets of langerhans.
What are signs of diabetes mellitus?
Persistent hyperglycaemia
Fasting blood glucose >7mmol/l
normal is 4-7
What are long term complications of diabetes mellitus?
Retinopathy
Renal failure
Cardiovascular disease
Neuropathy
What process occurs in diabetes mellitus?
Lack of insulin Glucose can't be used = hyperglycaemia High glucose concentration in the blood Spills into urine - osmotic diuresis - polyuria Excessive thirst and weight loss Cells can't use the glucose Switch to metabolising fats Ketones Acidosis
What should happen in glucose homeostasis?
After eating
Insulin rises - facilitates entry of glucose into cells via glucose specific transporters
Insulin stimulates glycogen synthesis in liver and muscles
When fasting
Glucose concentration and insulin secretion fall
Stimulates glycogenolysis in liver and muscles. And stimulates hepatic gluconeogenesis from amino acids and ketones.
What is insulin?
Anabolic hormone that has key role in glucose metabolism
Has important effect on fat and protein metabolism
What happens in diabetic ketoacidosis?
Lipolysis if not enough glucose going into cells (its in the blood)
Produces free fatty acids and ketone bodies.
Accumalte in blood = metabolic acidosis
Dehydration, acidosis and hyperosmolaility = decreased consciousnesss, coma, death.
How would someone present with diabetes?
2-3 week history of lethargy, wt loss, polyuria, thirst
If not noticed - could present with DKA. Abdo pain, vomiting, coma.
What is treatment for diabetes type 1
Insulin
Subcut.
May need more in puberty growth spurt.
Can have pump therapy - better glycaemia control.
What can be consequence of insulin treatment of diabetes?
Hypoglycaemia.
excess insuline or inadequate carb intake.
Feel shaky
Tachycardia
Drowsy
Irritable
What is level of blood glucose for hypoglycaemia
<4mmMol/L
What is treatment for hypoglycaemia?
2 x dextrose tables
100mls sugary drink e.g. lucosade.
What is diabetes type 2?
Pancreas can still secrete insulin but you have peripheral insulin resistance.
Increased by fatty deposits in pancreas as become overweight.
What is treatment of type 2 diabetes?
Dietary control of carbs
metformin
What is homeostasis?
Propety of human biological system where the self-regulating process tends to maintain the balance for survival. Regulation takes place in defined internal environment.
Variable - Change detected by receptor - inputs to control centre - outputs to effector - variable responds to the effector to increase or decrease.
