Endocrinology Flashcards
What is acromegaly?
Excessive secretion of growth hormone in patients who have passed puberty
What is the condition called when there is excess growth hormone in children?
Gigantism
Where is GH secreted from?
Anterior pituitary
What regulates GH secretion?
Growth hormone releasing hormone (GHRH)
Somatostatin (inhibits GH)
Where is GH releasing hormone secreted from?
Hypothalamus
What is the function of GH?
Indirectly stimulating soft tissue and bone growth through the use of insulin-like growth factor 1 (IGF-1)
What is the main cause of acromegaly?
Pituitary tumour
What are the symptoms of acromegaly?
Sweating Headaches Increasing size of hands and feet Amenorrhea Infertility Muscle weakness Enlarged tongue Increased dental spacing Hoarse voice Prominent lower jaw
What test is done to diagnose acromegaly?
Oral glucose tolerance test
Glucose should inhibit GH secretion so after glucose GH levels should be undetectable. In acromegaly there is a failure to suppress GH.
What is the first line treatment of acromegaly?
Surgical removal of pituitary tumour
What nonsurgical treatments can be given to treat acromegaly?
Somatostatin analogues
Radiotherapy
Give 3 potential complications of acromegaly
Bitemporal hemianopia Carpal tunnel Diabetes Hypertension Osteoporosis Obstructive sleep apnea
What is Cushing’s Syndrome?
Excess cortisol in the blood
What is the main cause of Cushing’s syndrome?
Too much steroid medication (iatrogenic)
What is Cushing’s disease?
Excess cortisol due to a pituitary adenoma releasing excess ACTH.
ACTH dependent
Name the 3 sources that may cause excess cortisol in the body
Pituitary tumour
Adrenal tumour
ACTH-secreting Ectopic tumour
Which 4 cancers can ectopically secrete ACTH?
Small cell lung tumour
Thymus gland tumours
Islet cell tumours of the pancreas
Medullary carcinoma of the thyroid
Give 5 symptoms of Cushing’s
Weight gain centrally Depression Insomnia Amenorrhea Thin skin Easy bruising Stretch marks Acne Back pain Excessive hair growth (women) Polyuria
Give 5 signs of Cushing’s
Moon face Osteoporosis Proximal myopathy Increased pigmentation Kyphosis Buffalo hump Oedema
Why may a woman with Cushings have signs of hirsutism?
Excess ACTH stimulates excess testosterone to be released from the adrenal glands as well as excess cortisol
What condition is very commonly associated with Cushing’s?
Type II diabetes
How does the dexamethasone suppression test diagnose Cushing’s?
Give the patient a dexamethasone tablet. Dexamethasone should suppress ACTH release from the pituitary. The following morning test serum cortisol levels. If cortisol is still high then Cushing’s disease is diagnosed
How can the cause of Cushing’s be established from the dexamethasone suppression test?
Pituitary tumour –> at low dose high cortisol, high ACTH. At high dose, decreased cortisol
Ectopic tumour –> at low dose high cortisol, high ACTH. At high dose, high cortisol
Adrenal tumour –> at low dose high cortisol, low ACTH
Why are stand alone cortisol readings unrepresentative of Cushing’s disease?
Cortisol levels are cyclical and so readings cannot be compared against a standard.
How is Cushing’s disease treated?
Surgical removal of the tumour
Decrease steroid medication
What is Primary Hypoadrenalism (Addison’s disease)?
Destruction of the adrenal cortex which results in a lack of secretion of cortisol, aldosterone and the sex hormones
What are the two main causes of Addison’s?
Autoimmune reaction
TB infection
Give 5 symptoms of Addison’s disease
Fatigue Weight loss Anorexia Myalgia Dizziness Fainting Low self esteem Depression Skin pigmentation
What happens to sodium levels in Addison’s?
Decrease
What is an Addisonian crisis?
Severe hypotension and dehydration following trauma or an illness.
How is an Addisonian crisis treated?
Emergency cortisol
Sodium infusion
What tests can be done to help diagnose Addison’s disease?
U&Es, glucose, adrenal antibodies, FBC, Serum aldosterone, chest and abdo x-ray
Describe the ACTH stimulation test
Given synthetic ACTH to stimulate cortisol production. Cortisol should rise rapidly to >550 nmol/L but in Addison’s it will not
How is Addison’s managed in the long term?
Oral hydrocortisone
Monitor BP and serum electrolytes and weight
Educate patient on effects of long-term steroid use
When does secondary hypoadrenalism occur?
Secondary hypoadrenalism occurs when a patient has been taking long-term steroids and they suddenly stop them. The HPA axis has been suppressed due to the ectopic source of cortisol so when the patient suddenly stops the body cannot quickly adjust to making enough cortisol on its own.
In secondary hypoadrenalism, why is aldosterone secretion not affected?
Stimulation from angiotensin II
What happens to the aldosterone level in primary and secondary hypoaldosteronism?
Primary = high Secondary = low
How is secondary hypoaldosteronism treated?
Restart steroids and gradually reduce rather than come off in one go
If pituitary disease, can give synthetic ACTH
What is hyperthyroidism?
Excess thyroid hormone in the blood.
What is the epidemiology of hyperthyroidism?
Women more affected
Ages 20 to 40
What is Grave’s disease?
Autoimmune condition where antibodies are produced for the TSH receptor which stimulate more TSH to be produced. The TSH then creates more T3 and T4.
What are the two most common causes of nodular thyroid disease?
Iodine excess in the diet
Medications such as Amiodarone
Give 5 symptoms of hyperthyroidism
Weight loss Hyperactivity Palpitations Fatigue Weakness Diarrhoea Polyuria Menorrhagia Fine tremor Intolerance to warmth Gynaecomastia Proptosis Clubbing Goitre
What is a thyrotoxic storm?
Undertreated hyperthyroidism
Fever, seizures, vomiting, diarrhoea, jaundice, arrhythmias, heart failure, hyperthermia
How is a thyroid storm treated?
Propranolol
Antithyroid drugs
Potassium iodide
Corticosteroids
How is hyperthyroidism treated?
Propranolol (symptom control)
Radioiodine
Carbimazole (risk of agranulocytosis)
What is hypothyroidism?
Thyroid does not produce enough thyroid hormone
Give 3 ways hypothyroidism can occur
Autoimmune destruction
Excessive treatment of hyperthyroidism
Iodine deficiency
What is atrophic hypothyroidism?
T-cell mediated cytotoxicity against follicular cells in the thyroid
What is hashimoto’s disease?
Thyroid attacked by T-cells which causes a goitre to form due to infiltration of the thyroid with lymphocytes resulting in fibrosis.
What are the symptoms of hypothyroidism?
Tiredness Weight gain Cold intolerance Poor appetite Depression Thin hair Constipation Dry skin Hypertension Hypothermia Bradycardia
What investigations will be done for hypothyroidism?
FBC U&Es Cholesterol TSH T3/4
How is hypothyroidism treated?
Levothyroxine
What is Conn’s Syndrome?
Type of primary hyperaldosteronism from an aldosterone-producing adenoma
What are the symptoms of Conn’s syndrome?
Often asymptomatic
Can have weakness, cramps, polyuria, polydipsia
How is Conn’s syndrome treated?
Laparoscopic adrenalectomy
Spironolactone
What is diabetes insipidus?
Reduced ADH secretion from the posterior pituitary causing the passage of large amounts of dilute urine.
What happens to sodium and potassium levels in diabetes insipidus?
Hypokalaemia
Hypernatraemia
What are the symptoms of diabetes insipidus?
Polyuria
Polydipsia
Dehydration
Symptoms of hypokalaemia and hypernatraemia
What are the causes of a lack of ADH production?
Hypothalamus disease Pituitary disorder Neurosurgery Trauma Idiopathic Sarcoidosis
How is diabetes insipidus treated?
Identify and treat the cause
Give desmopressin which is synthetic ADH
What is SIADH?
Excessive ADH secretion from the posterior pituitary gland or another ectopic source.
Why does SIADH result in hyponatremia?
The level of sodium in the blood stays the same but because the blood fluid increases there is a dilutional hyponatraemia
What is the pathophysiology of SIADH?
ADH acts on the DCT and collecting duct to reabsorb water and dilute the blood. When ADH secretion is not suppressed excessive water is reabsorbed back into the blood
Give 5 potential causes of SIADH
Small cell lung tumour Meningitis Head injury TB Alcohol withdrawal Opiates Hypothyroidism
What are the clinical features of SIADH?
Nausea Myalgia Irritability Headache Cheyne-Stokes respiration
What is Cheyne-Stokes respiration?
Repeating cycles of deep and fast breathing followed by apnoea
How is SIADH diagnosed?
Euvolemic hyponatremia
Low serum sodium
High urine sodium
Low plasma osmolality
Absence of hypokalemia, hypotension and hypovolemia
Normal renal, adrenal and thyroid function
How is SIADH treated?
Treat underlying cause
Water restriction
Demeclocycline (inhibits action of ADH)
Tolvaptan (treats hyponatremia)
What is a microadenoma?
Pituitary tumour which is <1 cm across
What is a macroadenoma?
Pituitary tumour which is >1 cm across
What are the 3 histological types of pituitary tumour?
Chromophobe –> mostly non-secreting
Acidophil –> secrete GH or prolactin
Basophil –> secrete ACTH
What are the symptoms from a pituitary tumour?
Caused by raised intracranial pressure or from the abnormal pituitary secretions
Headaches, visual field defects, anopia, CN III, IV, VI palsy
What investigations are done if a pituitary tumour is suspected?
LH, FSH, Testosterone, TSH, T4, Prolactin, IGF-1, cortisol, U&Es, FBC, short synACTHen test, insulin tolerance test, MRI of pituitary
How is a pituitary tumour treated?
Hormone replacement
Transsphenoidal surgery to remove tumour
Radiotherapy
What is hypopituitarism?
Reduced secretion of pituitary hormones
In which order are pituitary hormones affected in hypopituitarism?
GH –> FSH –> LH –> prolactin –> TSH –> ACTH
Why may panhypopituitarism occur?
Irradiation
Surgery
Large tumour
In what situations will oxytocin and vasopressin be affected in hypopituitarism?
If the hypothalamus is affected as well
Give 3 hypothalamic causes of hypopituitarism
Kallmann's syndrome Tumour Inflammation Infection (TB/meningitis) Ischaemia
Give 3 pituitary stalk causes of hypopituitarism
Trauma Surgery Mass lesion Meningioma Carotid artery aneurysm
Give 3 pituitary causes of hypopituitarism
Tumour Irradiation Autoimmunity Inflammation Infiltration Ischaemia
How is hypopituitarism treated?
Oral replacement of steroids and thyroid hormones LH and FSH analogues Testogel to replace testosterone Oestrogen if premenopausal GH therapy in children
What is the main cause of primary hyperparathyroidism?
Adenoma of the parathyroid gland
How does hyperparathyroidism present?
Weakness, depression, tiredness, thirst, abdominal pain, bone pain, fractures
How is hyperparathyroidism diagnosed?
Serum calcium Serum PTH Phosphate LFTs X-ray DEXA scan for osteoporosis
How is hyperparathyroidism managed?
Increase fluid intake
Avoid thiazide diuretics
Remove tumour
What is the main cause of secondary hyperparathyroidism?
Chronic renal failure
Vitamin D deficiency
What 3 cancers can ectopically secrete parathyroid hormone?
Squamous cell lung tumour
Breast cancer
Renal cell carcinoma
What are the main causes of hypoparathyroidism?
Autoimmune destruction
DiGeorge syndrome
How is hypoparathyroidism treated?
Ca2+ supplements
Calcitriol
Synthetic PTH
How is hypoparathyroidism diagnosed?
Serum PTH
Calcium
Phosphate
LFTs
What is hyperprolactinemia?
Excess prolactin present in the blood
Give 4 reasons for hyperprolactinaemia
Pregnancy (physiological)
Pituitary prolactinoma
Pituitary stalk compression (causing reduced dopamine)
Drugs- metoclopramide, haloperidol, oestrogens
What are the symptoms of hyperprolactinemia?
Amenorrhoea, infertility, galactorrhea, weight gain, loss of libido, erectile dysfunction, loss of facial hair
How is hyperprolactinemia treated?
Dopamine agonists (bromocriptine) Removal of tumour
What is pheochromocytoma?
Neuroendocrine tumour of the medulla of the adrenal glands which secretes large amounts of noradrenaline and adrenaline
How does pheochromocytoma present?
Headaches Hypertension Tachyarrhythmias Flushing Weight loss Malaise Sweating Pallor Hyperglycaemia Pyrexia Abdominal pain
Give 4 complications of pheochromocytoma
MI Heart failure Cardiomyopathy Arrhythmias Stroke Coma Death
How is pheochromocytoma diagnosed?
Metadrenaline levels
24hr urine collection of catecholamines
CT abdomen
How is pheochromocytoma treated?
Alpha-blockers
Beta-blockers
Surgical resection of adrenal gland
What is the karyotype in Turner’s patients?
(45,X)
What are the features of Turner’s syndrome?
Short, underdeveloped ovaries, lack of periods, infertility, webbed neck, low hairline, spoon-shaped nails
Name 3 conditions Turner’s syndrome is associated with
Heart murmurs UTIs Hypothyroidism Hypertension Osteoporosis Scoliosis Diabetes Crohn's UC
What is the karyotype in Klinefelter’s patients?
(47,XXY)
What are the features of Klinefelter’s syndrome?
Tall, lack of secondary sexual characteristics, small testes, infertile, gynaecomastia, elevated gonadotropin levels
What is Multiple Endocrine Neoplasia (MEN)?
The occurrence of several functional tumours in multiple endocrine glands. The glands involved all have a similar embryological origin.
What are the features of MEN Type 1?
Presents in 30-50s
Parathyroid hyperplasia
Pancreatic tumours
Anterior pituitary tumours (prolactinoma or acromegaly)
May also get carcinoid syndrome (flushing, diarrhoea, palpitations, hypotension and right sided heart failure)
What are the features of MEN Type 2a?
Medullary thyroid carcinoma
Adrenal pheochromocytoma (bilateral)
Parathyroid hyperplasia
What are the features of MEN Type 2b?
Medullary thyroid carcinoma
Adrenal pheochromocytoma (bilateral)
Hyperplasia of autonomic ganglia in the intestinal wall
Mucosal neuromas on lips, cheek, tongue and glottis
How is MEN managed?
Removal of the tumours surgically
Treatment of symptoms as they present
Screen family members due to autosomal dominant inheritance
Ongoing surveillance to detect new tumours early
