iv. Endocrinology Flashcards
L76: Where are the adrenal glands located?
Right above the kidneys
L76: What type of hormones do they adrenal glands secrete and can you provide examples of these?
- Endocrine hormones;
- Adrenaline;
- Steroids (aldosterone + cortisol).
L76: What part of the adrenal glands produce steroids?
Outer cortex
L76: What part of the adrenal glands produce adrenaline?
Inner medulla
L76: What disease can destruction of adrenal tissue lead to?
Addison’s Disease - gland can’t make steroids (primary)
L76: What disease can excess adrenal action (glucocorticoids) lead to?
Cushing’s Disease
L76: What hormone is cortisol production, by the adrenal glands, stimulated by?
ACTH (adrenocorticotrophic hormone) from pituitary gland
L76: What hormone is ACTH production, by the pituitary gland, stimulated by?
CRH (corticotrophin releasing hormone) from hypothalamus
L76: By what type of feedback system is cortisol production regulated by?
Negative feedback (HPA axis)
L76: What is cortisol (and other steroids) produced from?
Cholesterol
L76: What is the main function of aldosterone?
Salt and water regulation to control blood pressure
L76: How does aldosterone regulate salt and water absorption?
- Renin-angiotensin system;
- Enhances Na+ reabsorption and K+ loss;
- Indirect effect on blood pressure.
L76: What drugs inhibit aldosterone?
- ACE inhibitors (angiotensin converting enzyme);
- AT2 blockers (block angiotensin receptors).
[both dilate blood vessels to reduce bp]
L76: List some side effects of ACE inhibitors.
- Cough;
- Angio-oedema;
- Oral lichenoids.
L76: Why do ACE inhibitors often cause patients to develop a cough?
Prevent the breakdown of compounds such as bradykinin which in turn accumulate in respiratory tract
L76: Why can ACE inhibitors cause angio-oedema?
- Elevated levels of bradykinin;
- Tissues act as if they’re inflamed;
- Sudden onset of fluid retention in tissues.
L76: If a patient presents with oral lichenoids as a result of their ACE inhibitors, what should you do?
- This is a tissue reaction to the medication (ulceration);
- Ask GP to change pt to AT2 blocker;
- bp still maintained without effect on tissues.
L76: What part of cells does cortisol act upon?
- Works inside nucleus of cells;
- Changes protein transcription.
L76: Naturally, when is most cortisol produced in the body?
During the night, circadian release
L76: What effect does cortisol have on insulin?
Inhibits insulin, stimulates gluconeogenesis and fat/ protein breakdown
L76: What effect does cortisol have on the immune system?
Lowers immune reactivity
L76: What effect does cortisol have on bone?
Inhibits bone synthesis
L76: Name a therapeutic steroid.
- Hydrocortisone;
- Prednisolone;
- Triamcinolone;
- Dexamethasone;
- Bethamethasone.
L76: What suffix do steroids usually end in?
- one
L76: What is the cortisol equivalent of hydrocortisone?
1
L76: What is the cortisol equivalent of prednisolone?
4
L76: What is the natural amount of steroids produced by the body per day?
14-15mg
L76: What happens to natural production of steroids if someone is receiving therapeutic steroids?
- Natural levels ‘swamped’;
- Negative feedback;
- Adrenal glands stop producing.
L76: What is the major issue with receiving long term therapeutic steroids?
- Adrenal gland atrophy;
- Shrink away and fail to ‘switch back on’ once therapy has stopped.
L76: How do the effects or therapeutic steroids generally compare to natural steroid production?
- Enhance glucocorticoid effect;
- Enhance mineralocorticoid effect.
L76: List some side effects of therapeutic steroids.
- Hypertension;
- Type 2 diabetes (prolonged raised insulin to combat inhibition by steroids);
- Osteoporosis;
- Increased infection risk;
- Peptic ulceration;
- Thinning of the skin;
- Easy bruising;
- Cataracts and glaucoma;
- Hyperlipidaemia (atherosclerosis);
- Increased cancer risk;
- Psychiatric disturbance.
L76: What can cause hyperfunction of the adrenal glands?
- Adrenal tumour (primary);
- Pituitary tumour (secondary).
L76: What is Conn’s Syndrome?
Hypertension caused by excess aldosterone in the adrenal glands (adrenal tumour or hyperplasia)
L76: What is the main function of aldosterone?
- Mineralocorticoid;
- Na+ conservation in the kidneys.
L76: Other than Addison’s disease, what can cause hypofunction of the adrenal glands?
Pituitary failure - can’t ask gland to make steroids (secondary)
L76: What are the signs (will see) of Cushing’s Syndrome?
- Centripetal obesity;
- Moon face + buffalo hump;
- Hypertension;
- Thin skin + purpura (blood spots);
- Muscle weakness;
- Osteoporotic changes + fractures.
[effects lipid/ fat metabolism and muscles/ bones]
L76: What are the signs (will experience) of Cushing’s Syndrome?
- Diabetes mellitus features;
- Poor infection resistance;
- Back pain/ bone fractures (due to osteoporotic changes);
- Psychiatric disorder (inc. depression);
- Hirsuitism (excess body hair);
- Skin + mucosal pigmentation (due to ACTH);
- Ammenorrhoea, impotence + infertility.
L76: Why does excess ACTH cause pigmentation of the skin/ mucosa?
- Interaction between ACTH and MSH (melanocyte stimulating hormone);
- Changes in protein sequences;
- Become more tanned/ pigmented;
- Often presents on oral mucosa.
L76: What can cause adrenal gland failure and subsequent hypofunction?
- Autoimmune gland destruction;
- Infection;
- Infarction.
L76: What can cause pituitary gland failure and subsequent hypofunction?
- Compression from other adenoma;
- Sheehan’s Syndrome (sudden drop in bp to gland during childbirth).
L76: What are the major causes of Addison’s Disease?
- Infection (TB);
- Autoimmune adrenalitis.
L76: Addison’s Disease usually has a slow onset, what are the signs of it?
- Postural hypotension (salt and water depletion);
- Weight loss and lethargy;
- Hyperpigmentation (not w secondary hypofunction);
- Vitiligo.
L76: What are the symptoms of Addison’s Disease?
- Weakness;
- Anorexia;
- Loss of body hair (females).
L76: What would a diagnostic test for Cushing’s Syndrome show?
High cortisol all of the time, independent of circadian rhythm
L76: What would a diagnostic test for Addison’s Disease show?
- High ACTH levels;
- Negative response (no plasma cortisol rise) to ACTH injection.
L76: When diagnosing the cause of adrenal hyperfunction, how do you distinguish if the issue is primary or secondary to the adrenal glands?
- Primary: i.e. adenoma in adrenal gland: Low ACTH but high cortisol (correct pituitary response);
- Secondary: i.e. adenoma in pituitary or ectopic ACTH production: High ACTH and high cortisol (pituitary is not responding to high plasma cortisol).
L76: When diagnosing the cause of adrenal hypofunction, how do you distinguish if the issue is primary or secondary to the adrenal glands?
- Primary i.e. destruction of the adrenal glands: High ACTH, low cortisol and negative to synthetic ACTH (pituitary gland is working to increase cortisol but adrenal glands do not respond);
- Secondary i.e. destruction of pituitary gland: Low ACTH, low cortisol but positive to synthetic ACTH (pituitary not producing ACTH to stimulate cortisol production).
L76: What is an Addisonian crisis?
- Not enough cortisol or aldosterone;
- Takes time to develop;
- Hypovolaemic shock (low bp/ faint/ vomit/ collapse);
- Hyponatraemia (loss of salts).
L76: How do you treat an Addisonian crisis?
- Give pt saline (to treat the Addison’s);
- Then steroid replacement;
- Hydrocortisone (cortisol);
- Fludrocortisone (aldosterone).
[done in A&E after ambulance referral]
L76: When must a patient with Addison’s Disease increase their dose of steroids?
- When the body would usually increase cortisol production;
- Increased physical stress (difficult extractions);
- Significant infection;
- Perioperative treatment (under GA);
- Vomiting (pills will not be kept down).
L76: Why is steroid therapy more complicated than thyroxine therapy?
Thyroxine levels are the same day to day, cortisol levels change
L76: When should steroid prophylaxis (usually) be given for the following treatments: routine restorative, simple extractions, minor oral surgery, severe dental infection?
Minor oral surgery and severe dental infection
L76: At what dose of therapeutic steroids do you not require steroid prophylaxis?
Above 15mg prednisolone
L76: For patients on 1-15mg/ day doses of prednisolone, what prophylaxis cover should be given?
Double oral dose, perioperatively (surgery ± 2 days)
L76: Why must a patient’s steroid history over the past 6 months be taken?
- Effects (on glands) will be there for months;
- Might require prophylaxis dose (IM if no tablets).
