Endocrinology Flashcards
Where does the thyroid attach to?
Thyroid cartilage
Cricoid cartilage
Trachea
What does the hypothalamus secrete with regard to the thyroid?
Thryotropin releasing hormone (TRH)
What does the pituitary secrete with regard to thyroid?
TSH
What hormones does the thyroid produce?
T3 and T4
Which thyroid hormone is more abundant?
T4 (90%)
Which thyroid hormone is more potent?
T3 (4x)
What is thyroid hormone needed for?
BMR, thermogenesis, metabolism, growth, normal CNS function
When are thyroid hormones at their highest?
At night
What is hypothyroidism?
Clinical effects of having a lack of thyroid hormone
What are symptoms of hypothyroidism?
Tiredness, lower mood, cold intolerance, weight gain, constipation, hoarseness, dry skin, decreased memory, myalgia, cramps
What are some signs of hypothyroidism?
Bradycardia, ataxia, cold hands, yawning, oedema, round puffy face
What is the difference between primary and secondary hypothyroidism?
Primary is a problem with the thyroid gland
Secondary is due to a problem in pituitary or hypothalamus
What are causes of primary hypothyroidism?
Hashimotos thyroiditis, iodine deficiency, past thyroidectomy, drug induced (amiodarone, lithium)
What are causes of secondary hypothyroidism?
Congenital, craniopharyngioma, panhypopituitarism,
What do TFTs show in primary hypothyroidism?
High TSH, Low T4
What is the management of hypothyroidism?
Thyroxine replacement - start at 50mcg and adjust every 4 weeks until optimised
When should you check TFTs after a dose change?
8-12 weeks
How many thyroxine need adjusted in pregnancy?
Dose increase by 25-50mcg
What are side effects of thyroxine?
Hyperthyroidism, worsening of angina, AF
What is hyperthyroidism?
Clinical effects of excess thyroid hormone
What are symptoms of hyperthyroidism?
Diarrhoea, weight loss, appetite increase, sweating, heat intolerance, palpitations, tremor, irritability, labile emotions
What are the signs of hyperthyroidism?
Fast/irregular pulse, warm moist skin, fine tremor, palmar erythema, lid lag, goitre, nodules, bruit
What are the specific signs of Graves disease?
Exophthalmos, pretibial myxoedema, thyroid acropachy
What are the main causes of hyperthyroidism?
Graves disease, toxic multinodular goitre, toxic adenoma, ectopic thyroid tissue, subacute thyroiditis, post partum thyroiditis, drugs (amiodarone/lithium)
What do TFTs show in hyperthyroidism?
Low TSH and high free T4
What is the management of hyperthyroidism?
Carbimazole
What is the major risk of carbimazole?
Agranulocytosis
What drug is given for hyperthyroidism during pregnancy?
Propythiouracil
What do TFTs show in sick euthyroid syndrome?
Low TSH and low T4
What do TFTs show in subclinical hypothyroidism?
High TSH normal T4
What do TFTs show in poor thyroid medication compliance?
High TSH normal T4
What surgical options are there for hyperthyroidism?
Thyroidectomy or radioiodine ablation
What is thyroid cancer strongly associated with?
Radiation
How does thyroid cancer present?
Palpable nodules. Often no signs of hypo/hyperthyroidism as does not secrete hormones
What is the commonest type of thyroid cancer?
Papillary
What is the 2nd commonest type of thyroid cancer?
Follicular
What is medullary thyroid cancer associated with?
MEN2
What does medullary thyroid cancer secrete?
Calcitonin
What thyroid cancer carries the worst prognosis?
Anaplastic
How is thyroid cancer treated?
Mainly surgical
What hormone regulates calcium homeostasis?
PTH
How does PTH work?
Stimulates osteoclast activity to get calcium released from the bones and increase calcium levels in the blood
What hormone does the opposite of PTH?
Calcitonin
What are symptoms of hypercalcaemia?
Hypertension, ulcers, fractures, abdominal pain, myopathy, polyuria, thirst/dehydration, confusion, renal stones
What are causes of hypercalcaemia?
Primary hyperparathyroidism Malignancy Drugs (vitamin D, thiazides) Granulomatous disease - sarcoid, TB Pagets disease Being bedridden
Who does primary hyperparathyroidism commonly affect?
Elderly females
What is primary hyperparathyroidism associated with?
MEN1
What do bloods show in primary hyperparathyroidism?
Increased calcium, decreased phosphate, increased PTH
What are the main causes of primary hyperparathyroidism?
Adenoma, hyperplasia, cancer
What is the treatment of primary hyperparathyroidism?
Total parathyroidectomy, conservative management if unsuitable for surgery (Cinacalet)
Why does secondary hyperparathyroidism occur?
Because of a low calcium
What are causes of secondary hyperparathyroidism?
Low dietary calcium, low vitamin D, chronic renal failure
What do bloods show in secondary hyperparathyroidism?
Low calcium, high phosphate, high PTH
What treatment do you use for secondary hyperparathyroidism?
Correct the causes
Phosphate binders, calcium & vitamin D
When does tertiary hyperparathyroidism occur?
After prolonged secondary hyperparathyroidism
What do bloods show in tertiary hyperparathyroidism show?
Increased calcium, increased phosphate, increased PTH
What are symptoms of hypocalcaemia?
Weakness, seizures, bronchospasm, QT prolongation, muscle cramps, paraesthesia, Trousseau sign, fatigue
What are causes of hypocalcaemia?
Hypoparathyroidism, vitamin D deficiency, chronic renal failure, pancreatitis, hyperventilation, bone mets
What do bloods show in primary hypoparathyroidism?
Low calcium, high phosphate, low PTH
What are causes of hypoparathyroidism?
Removal of parathyroids, DiGeorge syndrome, autoimmune, haemochromatosis
What is pseudohypoparathyroidism?
Failure of target cells to respond to PTH
What features do people with pseudohypoparathyroidism have?
Round faces, obesity, bracydactyly, low IQ
What do bloods show in people with pseudohypoparathyroidism?
Low calcium, high phosphate, normal/high PTH
What is pseudopseudohypoparathyrodism?
Same as pseudohypoparathyroidism but with normal biochemistry
How is hypoparathyroidism treated?
Calcium supplements and calcitriol
What is Pagets disease?
Abnormality of bone remodelling resulting in thick but weak bone
What do bloods show in Pagets?
An isolated rise in ALP
How is Pagets treated?
Bisphosphonates
Where are the adrenal glands found?
Bilaterally superior and medial to the upper poles of the kidneys
What are the adrenal glands composed of?
Outer cortex and inner medulla
What does the zona granulosa of the adrenal cortex secrete?
Mineralocorticoids
What does the zona fasciculata of the adrenal cortex secrete?
Glucocorticoids
What does the zona reticularis of the adrenal cortex secrete?
Sex steroids
What does the medulla of the adrenal gland secrete?
Catecholamines
What are the main causes of primary adrenal insufficiency?
Addisons disease, congenital adrenal hyperplasia, adrenal TB, adrenal malignancy, meningococcal septicaemia
What are the main causes of secondary adrenal insufficiency?
Lack of ACTH stimulation, iatrogenic (steroid use). pituitary/hypothalamic disorders
What is Addison’s disease?
Autoimmune destruction of adrenal glands
What are symptoms of Addison’s disease?
Lethargy, weakness, N&V, weight loss, salt craving, bronzed skin, hypotension
What does the biochemistry show in Addison’s?
Low sodium, High potassium
Hypoglycaemia
Metabolic acidosis
How is Addison’s investigated?
Short synacthen test (cortisol remains low)
How is Addison’s treated?
Hydrocortisone and fludricortisone
What are sick day rules for Addison’s?
Double dose of hydrocortisone
How is an Addisonian crisis treated?
Hydrocortisone 100mg IV/IM
1 litre IV saline/saline with dextrose over 1 hour
What is congential adrenal hyperplasia?
Group of autosomal recessive disorders