Endocrinology Flashcards
What peptide is used in making insulin?
C-peptide
Gliclazide functions by releasing vesicles stored within the pancreas containing insulin and C-peptide. This happens because insulin is derived from proinsulin and C-peptide is formed as a byproduct.
WHAT IS ACROMEGALY?
What is it caused by?
https://www.youtube.com/watch?v=54h3IUbvHDU
This is an abnormal enlargement of the extremities of the skeleton caused by hypersecretion of the pituitary growth hormone after epiphysial fusion
What does the hypothalamus release? What does this cause? In acromegaly
Release growth hormone releasing hormone
Stimulates pituitary to release growth hormone
Somatostatin (growth hormone inhibiting hormone)
Decrease growth hormone release from pituitary
What is the difference between gigantism and acromegaly?
Difference in when growth hormone is released
- Gigantism - Before the closure of the epiphyseal plates, end up very tall
- Acromegaly - After the closure of the epiphyseal plates
What is the cause of acromegaly?
- 95% of cases are due to a growth hormone secreting Pituitary adenoma
- Less than 3% of cases are due to ectopic GHRH production - carcinoid tumours especially bronchial, pancreatic islet tumours or adrenal tumours
- Less than 2% of cases result from ectopic GH secreting pancreatic islet tumours
What are the symptoms of acromegaly?
- Coarse facial appearance, spade-like hands, increase in shoe size
- Large tongue, prognathism, interdental spaces
- Excessive sweating and oily skin: caused by sweat gland hypertrophy
- Features of pituitary tumour: hypopituitarism, headaches, bitemporal hemianopia
- Raised prolactin in 1/3 of cases → galactorrhoea
- 6% of patients have MEN-1
What are the signs of acromegaly?
-
Skin darkening
- Acanthosis nigricans
- Face
-
Big supraorbital ridge
- Interdental separation
- Macroglossia
- Prognathism
- Laryngeal dyspnoea
-
Spade-like hands and feet
- Tight rings
- Carpal tunnel syndrome
How can you diagnose acromegaly?
-
IGF-1 (somatomedin) tells tissues to grow
- Elevated
-
Glucose tolerance test
- 75g or glucose
- Wait 90 mins measure growth hormone levels
- Will stay elevated! Should decrease
-
Pituitary MRI
- Could be no tumour, could be ectopic source
Growth hormone levels
Not usually used because pulsatile
What is the treatment of acromegaly?
- Trans-sphenoidal Surgery - FIRST LINE
-
Medications to suppress GH
-
Somatostatin analogue
- Octreotide
-
Recombinant GH receptor antagonist
- Pegvisomant
-
Dopamine agonist
- Bromocriptine
-
Somatostatin analogue
- Radiation is sometimes used in older patinets or failed medicaitons
What are the complications of acromegaly?
- Hypertension
- Diabetes (>10%)
- Cardiomyopathy - MAIN CAUSE OF DEATH
- Colorectal cancer
WHAT IS CUSHING SYNDROME?
https://www.youtube.com/watch?v=ea1sXgd5ui8
Cushing’s syndrome refers to the set of clinical features resulting from persistently and inappropriately elevated levels of glucocorticoid. Usually the condition is iatrogenic
What is the electrolyte abnormality in cushing syndrome?
Hypokalaemic metabolic alkalosis
What does excess cortisol lead to?
Overload of what it normally reacts with
- Severe muscle, bone and skin breakdown
- Hypertension
- Inhibit gonadotropin releasing hormone from hypothalamus
- Dampens inflammatory response
- More susceptible to infections
- Impair normal brain function
What does elevated breakdown of muscle, bone and skin cause?
(What does this produce)
IN CUSHINGS
Elevated blood glucose
High insulin levels
Targets adipocytes in center of body
Activates lipoprotein lipase
Accumulate more fat molecules
Cause
Moon face
Buffalo neck hump
How is hypertension caused by excess cortisol?
- Amplifies effect of catecholamines on blood vessels
- Cortisol cross reacts with mineralcorticoid recptors
- Mineralcorticoids released from zona glomerulosa
- Triggers mineralcorticoid effect which is increasing blood pressure by retaining fluid - ALDOSTERONE
What are the causes of Cushing’s?
-
ACTH dependent causes
- Cushing’s disease (80%): pituitary tumour secreting ACTH producing adrenal hyperplasia
- Ectopic ACTH production (5-10%): e.g. small cell lung cancer is the most common causes
-
ACTH independent causes
- Iatrogenic: steroids
- adrenal adenoma (5-10%)
- adrenal carcinoma (rare)
- Carney complex: syndrome including cardiac myxoma
- micronodular adrenal dysplasia (very rare)
What are the symptoms of Cushing’s?
- Muscle wasting and thin extemities
- Easy brusing
- Abdominal striae
- Fractues - osteoporisis
- Full moon shaped face
- Buffalo hump
- Truncal obesity
- Hypergylcemia
- Diabetes mellitius
- Hypertension
- Cardiovascular disease risk
- Increase vulnerability to infections
- Poor wound healing
- Amenorrhea
- Psychiatric
What is the diagnosis of Cushing’s?
-
ENDOGENOUS / 24 urine sample
- Measuring free cortisol - urine 3.5-4.5 microgram/day
-
1 mg Dexamethasone suppresion test
- Low dose of dexamethasone (steroid)
- Supressess ACTH production
- Should cuase decrease cortisol levels <2
-
2mg Dexamethasone Supression Test
-
ACTH plasma levels checked
- Low ACTH + Cotrisol gives diagnosis of
- Adrenal adenomas and carcinoma
- High ACTH + Cortisol gives diagnosis of
- Cushing disease and ectopic ACTH production
-
ACTH plasma levels checked
-
8mg Dexamethasone Supression
- Pituitary - Cortisol + ACTH suppressed
- Ectopic - Cortisol + ACTH NOT suppressed
What types of imaging can be used for Cushing’s?
- MRI of pituitary
- CT of adrenals
- CT of chest abdomen or pelvis for ectopic
What is the treatment for Cushing’s?
-
Exogenous
- Drug is gradually stopped
- Adrenal crisis if too fast
- Adrenal glands might be atrophied
-
Endogenous
- Surgery
- Adrenal steroid inhibitors - Ketoconazole and metyrapone
- Most useful ectopic
ALL PATIENTS MUST UNDERGO LABROATORY EVALUATIONS SCREENING FOR HORMONE HYPERSECRETION AND HYPOPITUITARISM
What are you at risk of if you have your adrenals removed?
Nelson’s syndrome
Skin pigmentation increase
WHAT IS SYNDROME OF INAPPROPRIATE SECRETION OF ADH?
(Start with what it results in)
https://www.youtube.com/watch?v=0NHT8ERUBo0
- Hyponatremia and hypo-osmolality
- From inappropriate, continued secretion of ADH
- Despite normal or increased plasma volume
- Which results in impaired water excretion
What causes SIADH?
Drug-induced
- Selective serotonin reuptake inhibitors
- Carbamazepine
- Tricyclic antidepressants
Neoplastic
- Small cell lung cancer
- Mesothelioma
- GI tract malignancy
Pulmonary
- Pneumonia - especially Legionella and Mycoplasma
- Tuberculosis
CNS
- Tumour
- Meningitis, encephalitis
- Head injury
Miscellaneous
- Guillain–Barre syndrome
- Multiple sclerosis
- Acute intermittent porphyria
What are the symptoms caused by in SIADH?
Derived from decreased sodium in the blood
What are the symptoms of SIADH?
Stupor/coma
Anorexia (nausea and vomiting)
Lethargy
Tendon reflexes decreased
Limp muscles (weakness)
Orthostatic hypotension
Seizures/headache
Stomach cramping
What is the diagnosis of SIADH?
Sodium
- Plasma sodium concentration <135 mmol/l
- Urinary sodium concentration >30mmol/L
Osmolality
- Plasma osmolality <280 mOsmol/kg
- Urine osmolality > 100 mOsmol/kg
Other
- Patient clinically euvolaemic
- Absence of clinical or biochemical features of adrenal and thyroid dysfunction.
- No diuretic use (recent or past)
What is the treatment for SIADH?
Treat underlying cause
Acute
Hypertonic (3%) saline given via continuous infusion
Intravenous furosemide 20 to 40 mg
Chronic
For most other cases of mild-to-moderate SIADH, fluid restriction represents the least toxic therapy, and has generally been the treatment of choice
WHAT IS PRIMARY AND SECONDARY HYPOTHYROIDISM?
Primary is a reduction in thyroxin (T4)
Secondary is a reduction in TSH
What are the causes of primary hypothyroidism?
- Primary atrophic hypothyroidism (No goitre)
- Hashimoto’s thyroiditis (Goitre)
- Iodine deficiency
- Post-thyroidectomy / radioiodine / antithyroid drugs
- Lithium / amiodarone
What are the causes of secondary hypothyroidism?
Hypopituitarism
What is the epidemology of hashimoto’s thyroiditis?
Older Women
What are the symptoms of hypothyroidism?
RS
Hoarse voice
GI
Constipation
Int
Cold intolerance
Endo
Weight gain
UG
Menorrhagia
MSK
Myalgia, weakness
Neuro / Psych
Tired, low mood, dementia
What are the signs of hypothyroidism?
- *B**radycardic
- *R**eflexes relax slowly
- *A**taxia (cerebellar)
- *D**ry, thin hair / skin
- *Y**awning / drowsy / coma
- *C**old hands +/- ↓T°C
- *A**scites
- *R**ound puffy face
- *D**efeated demeanour
- *I**mmobile +/- Ileus
- *C**CF
What are the investigations for hypothyroidism?
-
TFT
- TSH RAISED
-
Lipids/cholesterol
- High
-
FBC
- Macrocytic anaemia
What are the disease associations of hypothyroidism?
AUTOIMMUNE
- VITILIGO
- Type 1 Diabetes Mellitus
- Addison’s disease
- Pernicious anaemia
- Primary biliary cirrhosis
INHERITED
- Turner’s syndrome
- Down’s syndrome
- Cystic fibrosis
What is the treatment of hypothyroidism?
- Levothyroxine (T4)
- Higher doses in the young
When should calcium be taken if patient is also taking levothyroxine?
Calcium 4 hours after levothyroxine
WHAT A HYPOTHYROID CRISIS?
Myxoedemic coma
What are the features of myxoedema coma?
Myxoedema coma typically presents with confusion and hypothermia
What is the treatment of a myxoedema coma?
- IV thyroid replacement
- IV corticosteroids (until the possibility of coexisting adrenal insufficiency has been excluded)
- THEN IV fluid
- electrolyte imbalance correction
- sometimes rewarming
WHAT IS HASHIMOTO’s THYROIDITIS?
(inside hypothyroidism)
Autoimmune disease
T cell mediated attack
What are the symptoms of hasimoto’s thyroiditis?
- Goitre or hypothyroidism or both
- Enlargement is usually slow and painless but rarely, may be more rapid and painful
What are the investigations for hasmimoto’s thyroiditis?
The condition may be suspected clinically on the basis of the goitre with or without hypothyroidism.
-
Serum TSH is usually raised
- Measurement of antithyroid antibodies reveal:
* *Thyroid peroxidase antibodies (TPO)** (previously known as thyroid microsomal antibodies) - HIGH titre - Thyroglobulin antibodies (TgAb) - HIGH titre
- Measurement of antithyroid antibodies reveal:
- Biopsy may be necessary to distinguish it from a carcinoma of the thyroid
What is the treatment of hasimoto’s thyroiditis?
- If the patient is hypothyroid then oral thyroxine may keep the patient euthyroid and lead to resolution of the goitre.
WHAT IS TOXIC MULTINODULAR GOITRE?
Toxic multinodular goitre describes a thyroid gland that contains a number of autonomously functioning thyroid nodules resulting in hyperthyroidism
What is the treatment for toxic multinodular goitre?
- Radioactive iodine
WHAT IS HYPERTHYROIDISM?
Too much thyroid hormones
What are the causes of hyperthyroidism?
- GRAVES’ DISEASE
- TOXIC MULTINODULAR GOITRE
- EXOGENOUS (Iodine / T4 excess)
- DE QUERVAIN’S THYROIDITIS (post-viral)
What are the symptoms of hyperthyroidism?
CVS
Palpitations
GI
Diarrhoea
Int
Heat intolerance
Endo
↓Weight, ↑appetite
UG
Oligomenorrhoea +/- infertility
Neuro / Psych
Tremor, irritability, labile emotions
What are the signs of hyperthyroidism?
HANDS
Palmar erythema; warm, moist skin; fine tremor
PULSE
Tachycardia; SVT; AF
FACE
Thin hair; lid lag / retraction
NECK
Goitre; nodules; bruit
What are the investigations for hyperthyroidism?
-
TFT
- Increase T4 and T4
-
FBC
- Normocytic anaemia
- ESR (↑)
- Calcium (↑)
- LFT (↑)
- Thyroid autoantibodies
- Visual fields, acuity, eye movements
What is the treatment for hyperthyroidism?
Depends on underlying cause
-
β-blockers
- Propanolol(rapid control of symptoms)
-
Antithyroid medication
- Carbimazole SE = AGRANULOCYTOSIS
- Block and replace (carbimazole + thyroxine)
- Propythiouracil
- Radioiodine (131I)
- Thyroidectomy
WHAT HAPPENS IN GRAVES DISEASE?
What are the triggers?
Autoimmune
IgG autoantibodies bind to and stimulate TSH receptors
Infection, stress, childbirth
What is a risk factor for grave’s?
Smoking
What are the symptoms of graves disease?
- Hyperthyroidism
- Diffuse goitre
- Extrathyroid features:
-
Thyroid acropachy, a triad of:
Digital clubbing
Soft tissue swelling of the hands and feet
Periosteal new bone formation - Graves’ ophthalmology - 40% of cases
- Pretibial myxoedema - 5% of cases
- Thyroid acropachy - rare
- Onycholysis - not specific to Grave’s!!
-
Thyroid acropachy, a triad of:
What are the investigations for Grave’s disease?
- Thyroid peroxidase antibodies
- TSH receptor stimulating antibodies
- Radioactive iodine uptake and scan
- Diffuse, homogenous, increase uptake of radioactive idodine
- Thyroid ultrasound scan
What is the treatment of Grave’s disease?
- Propanolol
- Use to help block the adrengergic effects
- Carbimazole - first-line
- Radioactive idodine
- Thyroidectomy
What are some causes of goitre?
- Physiological
- Graves’ disease
- Hashimoto’s thyroiditis
- De Quervain’s - TENDER GOITRE
WHAT IS A THYROID STORM?
Thyroid storm is a rare but life-threatening complication of thyrotoxicosis. It is typically seen in patients with established thyrotoxicosis and is rarely seen as the presenting feature. Iatrogenic thyroxine excess does not usually result in thyroid storm.
What are the precipitating events to a thyroid storm?
- thyroid or non-thyroidal surgery
- trauma
- infection
- acute iodine load e.g. CT contrast media
What are the clinical features of a thyroid storm?
- fever > 38.5ºC
- tachycardia
- confusion and agitation
- nausea and vomiting
- hypertension
- heart failure
- abnormal liver function test - jaundice may be seen clinically
What is the management of a thyroid storm?
- Symptomatic treatment e.g. paracetamol
- Treatment of underlying precipitating event
- Beta-blockers: typically IV propranolol
- Anti-thyroid drugs: e.g. methimazole or propylthiouracil
- Lugol’s iodine
- Dexamethasone - e.g. 4mg IV qds - blocks the conversion of T4 to T3
WHAT ARE THE MOST LIKELY THYROID CELL TYPE CANCERS?
- Papillary (60%)
- Follicular (≤25%)
- Medullary (5%)
- Lymphoma (5%)
- Anaplastic
What are some causes of thyroid cancer?
- Low dose radiation
- Radioiodine
- A history of radiation exposure to the neck area is associated with increased risk of thyroid cancer
What are the symptoms of thyroid cancer?
A rapidly growing hard thyroid mass with lymphadenopathy and indicators of extrathyroidal invasion
e.g. hoarseness, dysphagia is suggestive of maligancy.
What are the investigations for thyroid cancer?
Fine needle biopsy - the most effective method of distinguishing benign from malignant nodules.
Tumour products - basal and pentagastrin-stimulated serum calcitonin distinguishes medullary carcinoma.
Ultrasound - not useful as a primary test but may help to distinguish cystic lesions
Thyroid scanning with radioiodine - thyroid cancer is characteristically
Chest X-ray - lung secondaries
What is the treatment for thyroid cancer?
Most thyroid tumours are treated surgically with follow up radioiodine ablation
What is used to yearly to detect for early thyroid cancer reoccurance?
- Thyroglobulin levels
- Except in medullary - calcitonin
WHAT IS PRIMARY ADRENAL INSUFFIENCY?
https://www.youtube.com/watch?v=V6XcBp8EV7Q
The adrenal glands can’t produce enough hormones
Aldosterone and cortisol
Primary refers to the adrenal glands themselves
What are the different layers of the adrenal glands?
Cortex
Zona glomerulosa
Zona fasiculata
Zona reticularis
Medulla
What does each layer of the adrenal cortex produce?
- Zona glomerulosa - Aldosterone
- Zona fasiculata - Cortisol and glucocorticoids
- Zona reticularis - Make androgens E.g. deyhydroepiandosterone, Precursor to testosterone
What does the renin, angiotensin aldosterone system do?
Decrease potassium
Increase sodium
Increase blood volume and pressure
What are the causes of primary adrenal insuffiency?
- Autoimmune destruction
- Tuberculosis
- Metastases (e.g. bronchial carcinoma)
- Meningococcal septicaemia (Waterhouse-Friderichsen syndrome)
- HIV
- Antiphospholipid syndrom
What happens if the zona glomerulosa is destroyed?
- Aldosterone levels fall
- Leads to high potassium levels in the blood
- Low sodium - hyponatremia
- Low sodium water moves out of the blood vessels
- Hypovolemia
- High protons in blood
- Metabolic acidosis since it’s caused by the kidneys
What are the symptoms if the zona glomerulosa is affected?
Cravings for salty foods
Nausea and vomiting
Fatigue
Dizzyness
What are the symptoms if the zona fasiculata is destroyed?
Fatigue in times of stress
Hyperpigmentation on knuckles and joints
What happens if the zona reticularis is destroyed?
Men not affected
Testes major source of male androgens
Females
Loss of pubic hair
decreased sex drive
What does primary adrenal insuffiency usually need to cause symptoms?
Symptoms often slow,
Major stressor comes along
Injury, surgery or infection
Cause symptoms to appear
Sudden need for aldosterone and cortisol
How can you diagnose addison’s disease?
-
ACTH hormone test
- Small amount of synthetic ACTH injected
- Measure cortisol and aldosterone produced
- Both will be low
- Serum cortisol
-
Bloods
- FBC(anaemia, eosinophilia)
- U&E(↓Na+, ↑K+, ↑Ca2+, ↑Urea)
- BM(↓)
What is the treatment for addison’s disease?
- Cortisol - hydrocortisone
- Aldosterone - Fludrocortisone
- Dehydroepiandrosterone (DHEA)
If a patient with Addison’s disease becomes acutely unwell what is needed to be done to their medications?
- Double the glucocorticoid
- Keep the fludrocortisone dose the same
What is it called when the body suddenly needs aldosterone or cortisol and the body can’t deliver?
Addisonian crisis (acute primary adrenal insufficiency)
What syndrome can cause an addisonian crisis?
Waterhouse-friderichsen syndrome
Causes blood vessels in adrenal glands to rupture
What are the symptoms of addisonian crisis?
- Pain in back abdomen or legs
- Vomiting and diarrhoea leading to dehydration
- Low blood pressure leading to loss of consciousness
- Death