Endocrinology Flashcards
Where is the inferior parathyroid derived from?
Third pharyngeal pouch
Where is the superior parathyroid derived from?
Fourth pharyngeal pouch
Most common cause of congenital adrenal hyperplasia?
21-hydroxylase deficiency
Features of 21-hydroxylase deficiency in CAH?
Virilisation of girls
Precocious puberty in boys
Features of 11-beta hydroxylase deficiency in CAH?
Virilisation in female genitalia
Precocious puberty in boys
Hypertension
Hypokalaemia
Features of 17-hydroxylase deficiency?
Non-virilising in females
Inter-sex in boys
Hypertension
What happens to the electrolytes in Cushing’s syndrome?
High sodium
Low potassium
Where is melatonin synthesised from?
Melatonin is synthesised in the pineal gland from serotonin
What is the age range for normal puberty in boys?
9-14 years
What is the age range for normal puberty in girls?
8-14 years
Outline the normal sequence of puberty in girls?
Breast development
Height spurt
Menarche
What is the normal sequence of puberty in boys?
Testicular growth
Enlargement of the penis
Pubic hair development
Facial hair
Height growth
What are the causes of advanced bone age?
Endocrine causes - precocious puberty, adrenal pathology (CAH, adrenocorticol tumour), intracranial lesions (astrocytoma, craniopharyngioma), Cushing’s syndrome, hyperpituitarism, hyperthyroidism
Genetic causes - Soto’s syndrome, McCune Albright, Beckwith-Wiedemann, Homocystinuria, Marshall-Smith
Causes of delayed bone age?
Constitutional growth delay
Chronic disease
Neglect
IUGR
Genetic disorders (trisomy 21, trisomy 18, Turner syndrome)
Congenital dwarfism
Endocrine (hypothyroidism, hypopituitarism, hypogonadism, Cushing disease, diabetes, Addison’s disease, hypoparathyroidism)
Hormone profile in Kallman’s syndrome?
Reduced testosterone
Reduced LH/ FSH
Where is PTH secreted from?
Chief cells in the parathyroid hormone
What are the actions of PTH?
Bone - Binds to osteoblasts which signal to osteoclasts to cause resorption of bone and release calcium
Kidney - Active reabsorption of calcium and magnesium from the distal convoluted tubule. Decreases reabsorption of phosphate
Intestine - Increases intestinal calcium absorption by increasing activated vitamin D. Activated vitamin D increases calcium absorption
Where is glucagon released?
Alpha cells in the Islet of Langerhans
Where is Insulin released?
Beta cells in the Islet of Langerhans
Where is Somatostatin released?
Delta cells in the Islet of Langerhans
Which hormone DECREASES prolactin secretion?
Dopamine
Which hormone INCREASES prolactin secretion?
Thyrotropin releasing hormone
(also pregnancy, oestrogen, breastfeeding, sleep, stress, metoclopramide, antipsychotics)
Congenital adrenal hypoplasia =
Children often present in the neonatal phase with an adrenal crisis (hyponatraemia, hyperkalaemia, hypotension, dehydration, hypoglycaemia)
Where is secretin released?
Mucosal cells in the duodenum and jejunum
What are the likely blood results for adrenal insufficiency e.g. Addisons disease?
Low cortisol
High renin
Low sodium
High potassium
Hypoglycaemia
Metabolic acidosis
Which amino acid are all catecholamines derived from?
Tyrosine
Where is adrenaline and noradrenaline secreted from?
The chromaffin cells of the adrenal medulla
What is the most common thyroid malignancy?
Papillary carcinoma
What is the hormone profile for PCOS?
Raised LH:FSH ratio
Insulin resistance
High dehydroepiandrosterone (DHEA-S)
High free and total testosterone
Normal oestrogen
Causes of hypokalaemia with hypertension?
Conn’s syndrome
Cushing’s syndrome
Liddle syndrome
11 beta hydroxyls deficiency (cause of CAH)
Causes of hypokalaemia without hypertension?
Diuretics
GI losses
Renal tubular acidosis (type 1 and 2)
Bartter’s syndrome
Gitelman syndrome
Which drugs cause gynaecomastia?
Spironolactone
Digoxin
Cimetidine
Cannabis
Oestrogen
Anabolic steroids
Finesteride
What are the properties of octreotide?
Mimics somatostatin
Inhibits growth hormone and insulin
Function of ADH?
Purely concerned with water reabsorption therefore SIADH leads to normovolaemic hyponatraemia
What are psammoma bodies?
Clusters of microcalcifications - typically seen in papillary carcinomas (thyroid)
Which two hormones are released from the posterior pituitary?
ADH
Oxytocin
What are the criteria for diagnosis of McCune Albright syndrome?
Polyostotic fibrous dysplasia
Cafe-au-lait skin pigmentation
Autonomous endocrine hyperfunction (manifesting as hyperthyroidism, acromegaly, Cushing syndrome)
Where in the adrenal gland is cortisol produced
Zona fasciculata of the adrenal
Adrenal insufficiency causes…?
Hyponatraemia and Hyperkalaemia
Which cells produce testosterone?
Leydig cells secrete testosterone in response to LH stimulation
Treatment of minimal change disease?
Steroids (prednisolone)
ACEi
Diuretics
Immunosuppresants (cyclophosphamide)
Where does the left testicular vein drain into?
Left renal vein
Where does the right testicular vein drain into>
Inferior vena cava
Which pump defect is associated with distal renal tubular acidosis?
H+/K+ ATPase
Which abnormality predisposes to testicular torsion?
A patent processus vaginalis
Triad of thrombocytopenia, renal failure and microangiopathic haemolytic anaemia?
Haemolytic uraemia syndrome
What are the blood results for HUS?
Low platelets
High WCC
Increased urea
Increased creatinine
Increased LDH
Urine dipstick will show haematuria and proteinuria
Renal scarring investigation?
DMSA
Vesico-ureteric reflux disease?
Micturating cystourethrogram
Which nerve innervates the posterior skin of the scrotum?
Pudendal nerve
In what manner is growth hormone released?
Pulsatile manner
Features of hypercalcaemia?
Bones, stones, moans, groans
What are the features of polyglandular endocrinopathy type 1?
Mucocutaneous candidiasis
Addison’s disease
Parathyroid gland dysfunction
What are the features of polyglandular endocrinopathy type 2?
Most common type
Addisons disease and thyroid dysfunction +/- T1DM
What is the typical finding on a muscle biopsy in patients with thyroid disease?
Checkerboard pattern of necrosis and regeneration
What is somatostatin also known as?
Growth hormone inhibiting hormone
What does 5 alpha reductase deficiency cause?
XY males but have external female genitalia - androgen insensitivity syndrome
Which hormones are decreased in a stress reponse?
Insulin
Testosterone
Oestrogen
Causes of hypogonodotrophic hypogonadism?
Kallman’s syndrome
Prader-Willi syndrome
Bardet-Biedl syndrome
Causes of Hypergonadotrophic hypogonadism?
Noonan’s
Turners
Prader-Willi
Klinefelters
Identical twin risk of T1DM?
30-50%
Alcohol …. glucogenolysis?
Alcohol inhibits glycogenolysis
Which mutations account for MODY?
Glucokinase mutations
