Flashcards in General Endocrine Deck (59):
what is the trajectory of thyroid hormone in thyroiditis?
Increased thyroid hormone and then steep decline of thyroid hormone due to inflammation of the thyroid gland
would you do a core biopsy of a thyroid mass?
NO. FNA is less traumatic, rapid result
Core biopsy- thyroid gland very vascular and can significantly bleed with a large needle
what are some benign causes of thyroid nodules?
what are some malignant causes of thyroid nodules?
what is the most common type of thyroid cancer?
what type of cancer arises from the C cells of the thyroid gland?
what would you think if you aspirated a lot more colloid to cells via thyroid FNA?
when would you do a thyroid FNA for a thyroid nodule?
U/s features-if we see micro calcifications, hypoechogenicity, increased blood flow on the doppler
- FMH of thyroid cancer
-rapidly growing nodule
- hoarseness (recurrent laryngeal nerve)
what is the classification for thyroid FNA results?
when would you do a total thyroidectomy?
thyroid cancer > 1cm, hyperthyroidism
what are some adjunctive therapies to thyroid surgical resection?
1. radioactive iodine
2. Thyroid hormone suppression therapy
when would you operate on a MNG thyroid gland?
if it is symptomatic (obstruction, hoarseness, dysphagia) or if its cancerous and increasing in size
what are some anti-thyroid medications for an autonomous toxic thyroid nodule?
carbimazole and PTU
describe generally the mechanism of production of thyroid hormones
T3, T4 hormone mechanism of production:
1. Thyroglobulin protein synthesised in follicular cell and secreted into the colloid
2. Iodide is transported to the colloid via pendrin transporter
3. Binds to thyroglobulin --> forms MIT/DIT/T3/T4 complex
4. Complex is endocytosed back into the follicular cell
5. Iodine is recycled and T3, T4 are formed.
6. T3, T4 diffuse out of cell and enter the bloodstream bound to protein
what proteins do T3 and T4 bind to in the bloodstream?
thyroglobulin binding protein
what does a toxic adenoma in the thryoid gland do?
secretes excess thyroid hormone autonomously
A 32 yr old woman presents with fatigue and vitiligo. Has dark pigmentation over her appendectomy scar. On ex, a postural drop in blood pressure is noted. She is also hyperkalemic. What do you think is going on and what ix will most likely confirm the diagnosis?
Short synacthan test
what must you be worry about if administrating iodinating contrast for a patient with underlying hyperthyroidism?
May precipitate thyroid storm
what do we check c peptide for?
c peptide is produced with proinsulin and cleaved off proinsulin. Measuring c peptide may indicate how much endogenous insulin is actually being produced.
Usually measured in the setting of ix hypoglycaemia
Describe Addison's disease
Insufficient CORT production from adrenal glands
what can cause Addison's disease
key Ix of addison's disease
ACTH synacthan test
- so biochemical diagnosis, no imaging required
Symptoms of Addison's disease
• Weight loss
What do you expect for Addison's disease when you order serum electrolytes?
how do we medically manage Adrenal crisis?
dexamethasone/hydrocortisone + fluids
How do we medically manage addison's disease long term?
GC and MC
so dexa/hydrocortisone/pred + fludrocortisone (MC)
Opposite of SIADH?
why do we get hyponatremia in SIADH?
Too much ADH produced. ADH acts on the distal tubule placing aquaporins in the membrane, allowing for water to be retained by the body. As a result of this, TBW increases and this leads to hyponatremia. The hyponatremia is further exacerbated by the kidnye kicking out Na+
why should you never give dextrose fluids if you suspect SIADH?
essentially you are making the problem worse, because water goes everywhere in dextrose fluids
what are the broad categories of causes for SIADH?
how might we manage hyponatremia (in general)?
• Treat the underlying cause
• Fluid restriction- because usual suspects are SIADH and inappropriate fluid resuscitation
• However if GI losses apparent, normal saline
what causes hyperprolactinaemia other than a pituitary adenoma?
Hyperprolactinaemia is caused by dopamine antagonists such as:
Concentrations rise dramatically in pregnancy and are elevated in hypothyroidism and acromegaly and are raised in renal failure due to impaired clearance.
They are not elevated with LHRH.
SE of testosterone replacement therapy?
• Breast Cancer
• Reduced fertility
• Mood fluctuations
if you get a low testosterone serum level, what do you do?
repeat the test. testosterone levels change with time of day, they peak in the morning and decrease at night. So measure at 8am
what do you think when you see a man with very small testes?
how can you investigate hypogonadism?
test the following in the morning at 8am
-LH and FSH levels
what does low testosterone, low LH/FSH indicate?
what does low testosterone, high LH/FSH indicate?
what are some causes of primary hypogonadism in a male?
congenital Kleinfelter syndrome
what are some causes of secondary hypogonadism
Name some options for androgen replacement therapy?
1. IM testosterone enantate
2. SC testosterone pellets
3. transdermal testosterone patch/gel
4.oral testosterone undecanoate
why might we commence androgen replacement therapy for male patients with hypogonadism?
prevent osteoporosis, restore muscle bulk and libido
causes of gynaecomastia?
-too much oestrogen- CLD
-drugs- spironolactone, digoxin
-androgen deficiency syndromes
causes of hirsutism?
Anabolic steroid abuse
Androgen secreting tumour
key characteristic symptoms of Conn's disease?
hypertension, hypokalemia, metabolic alkalosis
what is the main cancer change associated with Conn's disease?
aldosterone secreting adrenocortical adenoma
how might we ix Conn's disease?
Measure renin and aldosterone levels in the plasma
measure urinary aldosterone
24 hr urinary collection to measure excess K+ excretion
which clinically apparent lymph nodes does papillary thyroid cancer metastasise to?
cervical lymph nodes
what is the main point of the water deprivation test for DI?
to differentiate cranial vs nephrogenic causes of DI.
cranial- able to concentrate urine post desmopressin administration
nephrogenic- unable to concentrate urine post desmopressin administration
what is tertiary hyperparathyroidism?
autonomously functioning parathyroid glands secreting high amounts of PTH subsequent to prolonged secondary hyperparathyroidism
what are the causes of hypoparathyroidism?
• Sustained damage to the parathyroid glands during thyroid surgery
• Copper or iron infiltration from haemachromatosis or Wilson's disease
Which part of the adrenal does Conn' syndrome and pheochromocytoma originate from?
Conn's = adrenal cortex
Phaechromocytoma= adrenal medulla
ix for phaechromocytoma?
1. urinary 24 hr catecholamines
2. plasma catecholamines
Symptoms of phaechromocytoma?
Periodic episodes of:
what is the mutation for MEN2
ret oncogene chromosome 10
3 parts of MEN 2a
Medullary thyroid carcinoma
3 parts of MEN1
What are some contraindications to testosterone replacement therapy?
desire to have a child
NYHF 3, 4
prostate cancer or breast cancer
hyper viscosity syndromes