128 Endocrine Flashcards by Jess Godfrey

Name the 4 types of hormones

peptide
aa derivatives
steroid
eicosanoids

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Are peptide hormones water soluble or lipid soluble?

Water soluble

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From which 2 sites is the peptide hormone somatostatin secreted from?

Hypothalamus and pancreas

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Which 2 peptide hormones does the posterior pituitary secrete?

Vasopressin

Oxytocin

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Which peptide hormone is secreted from the placenta?

hCG

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Which 3 peptide hormones are released from the pancreas?

Glucagon

Insulin

Somatostatin

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Where are steroid hormones synthesises?

Adrenal cortex

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Where do the steroid hormones bind to receptors?

(cellular)

Nuclear membrane

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Name the 3 zones of the adrenal cortex

Zona glomerulosa
Zona fasciculata
Zona reticularis

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Which steroid hormone is secreted from the Zona Glomerulosa of the adrenal cortex?

Aldosterone

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What is the role of aldosterone?

Control of BP - acts on the distal convoluted tubules and collecting ducts in the kidney to increase resorption of H₂O and increase BP

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What is the mechanism by which aldosterone is released from the Zona glomerulosa of the adrenal cortex?

RAAS system –> renin secreted from the kidneys in response to electrolyte conc of the blood. This converts angiotensiogen into angiotensin I. Angiotensin I into angiotensin II by ACE secreted by the lungs. Angiotensin II makes adrenal cortex secrete aldosterone

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Which glucocorticoid is secreted by the Zona fasciculata of the adrenal cortex?

Cortisol

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Where is cortisol secreted from?

Zona fasciculata of the adrenal cortex

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What is the role of cortisol? (3 listed)

Control of carbohydrate metabolism
- increases aa conc in the blood by inhibiting protein synthesis in tissues
- promotes use of fat for energy
- stimulates gluconeogenesis in the liver
Inflammatory response - suppresses by preventing Tcell proliferation
Stress response - ie redistributing glu to the areas which need it most

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Which steroid hormones are secreted from the zona reticularis in the adrenal cortex?

Sex hormones: androgens and oestrogens

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Which amino acid are the catecholamines derived from?

Tyrosine

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Which catecholamines are secreted by the adrenal medulla?

NA and adrenaline

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Which amino acid derived hormones are secreted from the thyroid gland?

T3 - triiodothyronine

T4 - thyroxine

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What are eicosanoids and what are they derived from?

Hormones/signalling molecules derived from PUFAs

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Which eicosanoid is involved with inflammation and pain sensation?

prostaglandin

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Which eicosanoid is involved with the increase of vascular permeability and vasodilation during inflammation?

thromboxanes

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Which enzymes catalyse oxygenation of fatty acids to produce eicosanoids?

COX (cyclooxygenase) and LOX (lysil oxidase)

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Which nucleus in the hypothalamus is responsible for circadian rhythm?

Suprachiasmatic nucleus

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In the stress response, which hormone is released from the hypothalamus to act on the anterior pituitary?

CRH (corticotropin releasing hormone) --\>ant pit secretes ACTH --\> acts on the adrenal cortex --\> secreted cortisol

Where is calcitonin secreted from?

Thyroid gland

What is the function of calcitonin? (3 ways in which it acts)

Acts to reduce serum [Ca²⁺] - opposite effect to PTH * Inhibits Ca2+ absorption by the intestines * Inhibits osteoclast activity in bones * Inhibits renal tubular cell reabsorption of Ca2+ allowing it to be excreted in the urine

What is the function of PTH?

To increase serum [Ca²⁺] by: * stimulating osteoclastic bone resorption * It enhances active reabsorption of calcium and magnesium from distal tubules and the thick ascending limb * It enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D

Which cells produce PTH?

Chief cells of the parathyroid gland

Which cells of the pancreas secrete glucagon?

α cells of the pancreas

Which cells secrete insulin in the pancreas?

β cells

What is the effect of glucagon secretion by the pancreas?

Causes glucose production by the liver - glycogenolysis and gluconeogensis therefore prevents **hypo**glycaemia

What is the effect of insulin secretion by the βcells in the pacreas?

Reduction in glucose plasma levels - prevents gluconeogenesis by the liver and increases glucose transport into cells. Prevents **hyper**glycaemia

Which investigations should be performed when suspecting differentiated thyroid Ca? (4 listed)

* USS * FNAC (fine needle aspiration and cytology) * serum thyroglobulin * whole body scans

What is the treatment for thyroid Ca?

Thyroid surgery/ radioiodine Rx (Iodine 131)

How can a goitre present?

Neck mass with compression symptoms

Which disease is associated with a goitre?

Hyperthyroidism

Which blood test should be performed when diagnosing a goitre?

TSH

What is the cause of primary hypothyroidism?

Insufficient TH produced by the thyroid

What is the diagnosis? * low metabolic rate * sensitivity to cold * poor memory * increased weight * elevated THS * low TH

Primary hypothyroidism

What would a low TSH level and low TH level indicate?

Secondary hypothyroidism

What is the treatment for primary hypothyroidism?

Thyroxine

Excess production of chatecolamines caused by adrenal/extra-adrenal tumour. What is the disease?

Pheochromocytoma

Which conditions are associated with pheochromocytoma? (4 listed)

* Von Hippel Lindau syndrome * phakomatoses * neurofibromatosis * multiple endocrine neoplasmas

Which investigations should be performed to diagnose pheochromacytoma?

* 24 hour urine --\> would show increased chatecholamines and metabolites

What is the diagnosis: excess aldosterone production from the adrenal cortex causing endocrine HTN ?

Conn's syndrome

What signs and symptoms are present in Conn'd syndrome? (3 listed)

* HTN * hypokalaemia * metabolic alkalosis

Which invesigations should be performed to confirm diagnosis of Conn's syndrome?

* 9am rennin and aldosterone --\> would show loe rennin and high aldosterone * U&EC * CT/MRI * MIBG scan - to rule out pheochromocytoma

What is a MIBG scan?

Iobenguane = radioisotope also referred to as MIBG used in scintography method called MIBG scan. Its a similar molecule to NA and so is useful for the diagnosis of pheochromocytoma/neuroblastoma

What is spironolactone used to treat?

Conn's syndrome if bilateral hyperplasia of adrenals

What is the treatment for Conn's syndrome if there's an adenoma present? What if bilateral hyperplasia?

* adrenalectomy if adenoma * low salt diet and spironolactone if bilateral hyperplasia

What is the most likely diagnosis? * Hyperpigmentation * general malaise * N&V * hypoglycaemia * postural hypotension * W/L * hyponatraemia * hyperkalaemia * inadequate cortisol response to synacthen * increased ACTH

Addisons disease

What is the treatment for Addisons disease?

* hydrocortisone - 10mg BD * fludrocortisone - 0.1mg OD

What is the immediate treatment of an Addisonian crisis?

100mg hydrocortisone IV

What syndrome is caused by excess cortisol production cause dby adrenal tumours, pituitary tumours or ectopic ACTH production?

Cushings

What is the diagnosis? - * central obesity * buffalo hump * moon face * HTN * poor wound healing * thin skin * hirsuitism * depression * fatigue

Cushing's syndrome

In Cushings, where is the disease if the ACTH levels are high?

Pituitary

In Cushings, where is the disease if ACTH is low?

Adrenals

What investigation should be performed to diagnose Cushing's?

* 24 hour dex test * give low dose dexamethasone at night - in normal individuals, it should cause cortisol suppression * cortisol not suppressed in Cushing's at 9am the next day

What condition is metyrapone used to treat?

Cushing's

What is the MOA of metyrapone in the treatment for Cushing's syndrome?

To reduce cortisol and corticosterone production by inhibiting the 11-ß-hydroxylation reaction

What condition is associated with a deficiency in 21 hydroxylase?

Congenital adrenal hyperplasia

Which pathway is 21-hydroxylase involved with in the adrenal cortex?

Glucocorticoid pathway ending in production of Aldosterone

Which condition causes reduced aldosterone secretion in children and excess androgen production in adults?

Congenital adrenal hyperplasia

What investigations should be performed when diagnosing congenital adrenal hyperplasia?

Synacthen

What is the cause of primary hyperparathyroidism?

Adenoma/hyperplasia of the parathyroid glands

What signs and symptoms are associated with primary hyperparathyroidism?

Generally asymptomatic but can have symptoms of hypercalcaemia: * Stones, moans and groans... * kidney stones * tiredness * muscle weakness * dehydration * N&V * bone pain * arrhythmias

What investigations should be performed to diagnose primary hypoparathyroidism? (4 listed)

* serum PTH (high) * serum Ca²⁺ (high) * serum P0₄^- (low) * urinary Ca²⁺ (high)

What is usually the cause of hypoparathyroidism?

Surgery - e.g. partial/complete thyroidectomy

What is the diagnosis? - * increased neuromuscular excitability * tingling in the extremities * tetany * epileptic convulsions * prolonged QT intervals * cataracts * low PTH * low Ca²⁺, high phosphate

Hypoparathyroidism

What symptoms are associates with hypomagnasaemia? (hint: causes low PTH secretion) 6 listed

* Increased neuromuscular excitibility * tingling in extremities * tetany * epileptic convulsions * prolonged QT intervals * cataracts

What can cause hypomagnasaemia?

* D&V * PPIs

What is 'knuckle knuckle dimple dimple' a characteristic of?

Albrights Hereditary Dystrophy in pseudohypoparathyroidism - short 4th and 5th metacarpals

What is the treatment for pseudohypoparathyroidism?

VitD

What can cause primary hypogonadism in males? (4 listed)

* Klinefelters * Castration * chemoTx * chronic liver/kidney disease

What are the signs and symptoms in primary hypogonadism in ♂

* small/ absent testes * gyneacomastia * infertility * decreased libido * decreased hair * osteoporosis

What is the treatment for primary hypogonadism in males?

* Testosterone * sildenafil * infertility Tx

What investigations should be performed to diagnose primary hypogonadism in males?

* bloods * testosterone (low) * LH (high) * FSH (high) * seminal analysis

What could primary amenorrhoea indicate?

Turners Foetal androgen deficiency

What is the treatment for precocious puberty?

LHRH

What could cause premature ovarian failure?

* previous chemo * organ specific immune disease

What are the S&S of PCOS?

* hirsuitism * acne

What is the treatment for PCOS?

* metformin * oestrogen and progesterone * infertility treatment