Endocrinology and Growth Flashcards
Major drivers of growth in infancy?
nutrition and insulin
Major drivers of growth in childhood?
growth hormone and thyroxine
Major drivers of growth in puberty?
Sex steroids and growth hormone
Effects of PTH on bone?
Binds to osteoblasts which signal to osteoclasts to cause resorption of bone and release calcium.
Effects of PTH on kidneys?
Active reabsorption of Ca and Mg from the distal convoluted tubule. Decreases reabsorption of PO4.
Effects of PTH on intestine (via kidneys)?
Increases intestinal calcium absorption by increasing activated vitamin D. Activated vitamin D increases calcium absorption.
Definition of PCOS?
at least two of the following:
(Rotterdam criteria):
- Polycystic ovaries (more than 12 cysts)
- Oligo-ovulation or anovulation
- Hyperandrogenism (clinical or biochemical)
Symptoms of PCOS?
- Oligomenorrhoea (defined as <9 periods per year)
- Infertility, subfertility
- Acne, oily skin, increased skin pigmentation
- Hirsutism, male pattern baldness or alopecia
- Obesity or difficulty losing weight
How can metformin help in PCOS?
Reduce insulin resistance Fall in serum androgens Induce ovulation Fall in LH Reduction in weight
What does LH and FSH do in males?
LH stimulates the testes -> testosterone.
FSH (and testosterone) causes the testes to produce sperm.
First sign of puberty?
enlargement of the testes (once they reach 4 ml, puberty has commenced)
Testicular size denoting commencement of puberty?
4mL
Stages of puberty?
enlargement of the testes -> lengthening of the penis -> pubic hair -> ejaculation/ facial hair
Brown-Sequard Syndrome features?
- ipsilateral spastic paralysis (corticospinal tract)
- ipsilateral loss of proprioception and vibration (dorsal column)
- contralateral loss of pain and temperature sensation (spinothalamic tract)
Effect of cortisol on BP?
Increases BP: permits normal response to angiotensin II and catecholamines by up-regulating a1 receptors on arterioles
Effect of cortisol on bone?
Inhibits bone formation: decreases osteoblasts, decreases type 1 collagen, decreases absorption of calcium from the gut, increases osteoclastic activity
Most common cause of primary adrenal insufficiency?
80 % due to autoimmune destruction (Addison’s disease)
Other causes: congenital adrenal hyperplasia, adenoma, or idiopathic
Most common cause of secondary adrenal insufficiency?
exogenous steroid use -> impairment of pituitary/ hypothalamus
other causes: pituitary adenoma, hypothalamic tumors, surgical damage, and Sheehan’s syndrome (maternal ischemic necrosis related to childbirth)
autosomal recessive condition: obesity, retinitis pigmentosa, polydactyly, hypogonadism, and kidney failure
Bardet-Biedl syndrome
children lose their vision by adolescence or early childhood
complications of thyroidectomy?
- postop haemorrhage and haematoma formation, this can rapidly compress the airway
- recurrent laryngeal n palsy -> hoarse voice
- hypoparathyroidism + low Ca due to removal/ damage of parathyroids
most common cause of thyroid problems?
autoimmunity.
Graves/ Hashimotos
What drug can cause thyrotoxicosis?
amiodarone
What is Riedel thyroiditis?
fibrous tissue replacing the normal thyroid parenchyma
causes a painless goitre + hypothyroidism
What drugs may cause hypothyroidism?
Lithium, Amiodarone
Most common cause of hypothyroidism in the developing world?
Iodine deficiency
Effects of thyroid dysfunction on periods?
hypothyroid - menorrhagia
hyperthyroid - oligomenorrhoea
Neurological symptoms of hypothyroidism?
Decreased deep tendon reflexes
Carpal tunnel syndrome
Most common antibodies in Hashimoto’s?
anti-Thyroid Peroxidase
Most common antibodies in Grave’s disease?
TSH receptor antibodies
Thyroglobulin antibodies
Mx of thyrotoxicosis?
dependent on underlying cause.
Propranolol: to control thyrotoxic symptoms such as tremor
Carbimazole: blocks thyroid peroxidase from coupling and iodinating the tyrosine residues on thyroglobulin → reducing thyroid hormone production. (SE: Agranulocytosis)
Radioiodine treatment
What is an arrhenoblastoma?
rare types of ovarian tumours which most often secrete testosterone -> virilisation of girls
as well as some oestrogen -> precocious puberty.
Tx of GnRH-dependent precocious puberty?
GnRH agonist
most common enzyme deficiency in congenital adrenal hyperplasia?
21-hydroxylase deficiency (90% of cases)
-> cortisol deficiency and sometimes an associated aldosterone deficiency and androgen excess
2nd most common enzyme deficiency in congenital adrenal hyperplasia?
11-beta-hydroxylase
features of salt-losing congenital adrenal hyperplasia?
Due to aldosterone deficiency, seen in the first few weeks of life as an adrenal crisis
Females have ambiguous external genitalia
features of non salt-losing congenital adrenal hyperplasia?
Presents during childhood with low glucocorticoids and high androgens
Males present with virilisation age 2-4 years
females - ambiguous external genitalia
Characteristics of McCune-Albright Syndrome?
At least 2 of 3:
1. polyostotic fibrous dysplasia (fibrous tissue in bones)
- café-au-lait spots
- autonomous endocrine hyperfunction (eg, gonadotropin-independent precocious puberty)
+/- hyperthyroidism, acromegaly, and Cushing syndrome.
Venous drainage of the adrenals?
R adrenal drains directly into IVC
L adrenal drains into L renal vein
Physical features of Turner’s syndrome?
- Lymphoedema and rocker bottom feet at birth
- Short stature
- Webbed neck
- Broad chest
- Less common: multiple naevi, poorly developed nails, ptosis, low hairline
Cardiac associations of Turner’s Syndrome?
- most frequently coarctation of the aorta
aortic dissection
bicuspid aortic valve
hypertension.
Endocrine features of Turner’s Syndrome?
relating to gonadal dysgenesis:
Amenorrhoea
Dlayed or absent puberty
Infertility
Mx of Turner’s Syndrome?
Growth Hormone to initiate puberty.
Once satisfactory growth and development has been achieved, GH stopped and oestrogen started.
Progesterone is added at the time of puberty to induce withdrawal bleeds.
Features of 17-hydroxylase deficiency?
congenital adrenal hyperplasia:
- non-virilising in females
- inter-sex in boys
- hypertension
Features of 11-beta hydroxylase deficiency?
congenital adrenal hyperplasia:
- virilisation of female genitalia
- precocious puberty in males
- hypertension
- hypokalaemia
Where is testosterone produced?
Leydig cells.
small amounts produced in the adrenal glands.
