Endocrinology Flashcards
Metabolic ketoacidosis with normal-low glucose is associated with what?
Alcoholic ketoacidosis
Which thyroid cells form the colloid?
Follicular cells
What mineral is associated with the thyroid colloid?
Iodine
What is the function of para-follicular cells (C-cells)?
Produce Calcitonin
What is the function of follicular cells?
Synthesise T4 and T3
What is the bioactive thyroid hormone?
T3
What is the main thyroid hormone produced by the thyroid gland?
T4
How is T4 transported int he blood?
Thyroid-binding globulin
What are the symptoms of hyperthyroidism?
Tremor Anxiety Palpitations Heat intolerance Diarrhoea Oligomenorrhoea
What are the symptoms associated with hypothyroidism?
Lethargy Cold intolerance Weight gain Constipation Menorrhagia Decreased deep tendon reflexes
What is the most common cause of hyperthyroidism?
Grave’s disease
What are the causes of hyperthyroidism?
Grave’s disease
Toxic multi-nodular goitre
Thyroiditis
Drugs (Amiodarone)
Which antibodies are associated with Grave’s disease?
Anti-TSH receptor antibodies
Which drug is associated with inducing hyperthyroidism?
Amiodarone
What is the most common cause of hypothyroidism?
Hashimoto’s thyroidits
Which auto-antibody is associated with Hashimoto’s thyroiditis?
Anti-TPO antibodies
What are the causes of hypothyroidism?
Hashimoto’s thyroiditis
Subacute thyroiditis
Drugs
Iodine deficiency -Common cause in the developing world
Which drugs can induce hypothyroidism (2)?
Lithium
Amiodarone
What is the most common cause of hypothyroidism in the developing world?
Iodine deficiency
What is the level of TSH in primary hyperthyroidism?
Low TSH
What is the level of TSH in primary hypothyroidism?
Raised
What is revealed in radio-scintigraphy in Grave’s disease?
Homogeneous increased iodine uptake
What is revealed in radio-scintigraphy in a toxic adenoma?
Hot nodule - increased iodine uptake in solitary nodule and suppressed uptake in other parts
What is revealed in radio-scintigraphy in a toxic multi-nodular adenoma?
Heterogeneous uptake
What is the management of hyperthyroidism?
Propranolol - Non cardioselective beta-blocker for symptomatic management
Carbimazole (TPO inhibitor)
Propylthiouracil
Radio-iodine
What are the side effects of carbimazole?
Agranulocytosis (No neutrophils)
What is the definitive management for hypothyroidism?
Levothyroxine
How common is thyroid eye disease in Grave’s patients?
25-50%
What is the most common form of thyroid eye disease in Grave’s?
Bilateral exophthalmos
What is the pathophysiology of exophthalmos in Grave’s?
Anti-TSH receptor antibodies binding to TSH receptors in the eyes - stimulates growth of tissue
What are the features of Bilateral exophthalmos in Grave’s?
Diplopia Conjunctival oedema (chemosis) Opthalamlgia Exposure keratopathy Optic neuropathy (Blurred vision)
Due to increased sympathetic tone in Grave’s disease what features are seen in the eye?
Lid lag and retraction
What are the three specific features in Grave’s disease?
Bilateral exophthalmos - lid lag and retraction
Pretibial myxoedema
Thyroid acropachy (Thickening of the extremities)
What are the classic features of thyroid cancer?
Non-functional (Euthyroid), painless, rapidly growing
Solitary - Irregular (Nodular shape
Palpable nodule, hard and fixed
Hoarse voice - Tumour compression on the recurrent laryngeal nerves
Dysphagia
Haemopotysis
Airway obstruction
Why does a hoarse voice occur in thyroid cancer?
Tumour compression on the recurrent laryngeal nerve
What is the most common subtype of thyroid cancer?
Papillary carcinoma (70%) - associated with cervical lymphadenopathy
What is the epidemiology of papillary carcinoma?
35-year old female with childhood radiation exposure
A circular concentric laminations in papillary carcinoma is known as what?
Psammoma body
What thyroid cancer is associated with a Psammoma body?
Papillary carcinoma
What is the second most common thyroid cancer?
Follicular carcinoma (20%) - associated with low dietary iodine intake
What is a rare variant of follicular carcinoma?
Hurthle cell carcinoma
Which MEN types are associated with medullary carcinoma?
MEN2a and MEN2B
What are the most aggressive thyroid cancers?
Anaplastic carcinomas
What is the definitive investigation for thyroid cancer?
Fine needle aspirate biopsy with ultrasound
+TFTs - to exclude functional nodules
What neoplasms are associated with MEN type 1?
3Ps Pituitary tumours (Prolactinoma)
Pancreatic tumours (Insulinoma, glucagonoma, gastrinomas)
Parathyroid adenomas
(Raised Ca, and HyperPTH)
What are the common pancreatic tumours are associated with MEN1?
Insulinoma
Glucagonoma
Gastrinoma
What are the symptoms of hypercalcaemia?
Renal colic Abdominal pain Constipation Psychological depression Bone pain, osteoporosis
What is the onset of symptoms for MEN1?
MEN1 mutation has high penetrance and therefore develops early in life.
What investigations are performed for MEN1?
CT/MRI (whole-body), genetic testing
What is Zollinger-Ellison syndrome compared with MEN1 gastrinoma?
Non-MEN1 gastrinoma
MEN2A and MEN2B is associated with which type of thyroid cancer?
Medullary thyroid cancer
Medullary thyroid cancer is associated with which type of cell?
Parafollicular C-cell - produce calcitonin
Which tumours are associated with MEN2A?
Phaeochromocytoma
Parathyroid adenoma
Medullary thyroid cancer
Which tumours are associated with MEN2B?
Phaeochromocytoma
Medullary thyroid cancer
Neuromas (Mucosal) -
Associated with Marfanoid habitus
What is Marfanoid habitus?
Including long limbs, with an arm span that is at least 1.03 of the height of the individual, and a crowded oral maxilla, sometimes with a high arch in the palate, arachnodactyly, and hyperlaxity.
Pectus excavatum
A Marfanoid habitus is associated with which type of MEN syndrome?
MEN2B
What gene is associated with MEN2A and 2B in genetic testing?
RET oncogene
What blood investigation is performed in suspected medullary thyroid carcinoma?
Calcitonin
What type of tumour is carcinoid syndrome?
Neuroendocrine cell
How does carcinoid syndrome arise to produce a symptomatic presentation?
The carcinoid tumour metastasises to the liver
What does serotonin get metabolised into by the liver?
5-HIAA (excreted via the urine)
What hormone is raised in carcinoid syndrome?
Serotonin
Bradykinin
Histamine
What are the common features of carcinoid syndrome?
Flushing (Vasodilation due to bradykinin and histamine)
Diarrhoea (Serotonin induced effect on gut motility)
Shortness of breath
Pulmonary stenosis
Abdominal pain (Serotonin activated fibroblasts)
Itching (Histamine)
What hormone inhibits serotonin release?
Somatostatin
What investigations are performed on suspected carcinoid syndrome?
Urinary 5-HIAA
CT Scan
Octreotide scan - specific
What is octreotide?
A somatostatin analogue
What specific scan is performed in carcinoid syndrome?
Octreotide scan - binds to neuroendocrine cells
What hormone released by the hypothalamus directly controls LH/FSH secretion?
GnRH
Which cells respond to LH in males?
Leydig cells
What is the function of Leydig cells?
Release testosterone
What is the function of Sertoli cells?
Spermatogenesis
Sertoli cells respond to which hormone?
FSH
Which hormone is secreted by theca cells?
Progesterone
Which hormone is secreted by granulosa cells?
Oestrogen
Which gonadotrophin acts on theca cells?
LH
What is physiological hypogonadism?
Pregnancy
What is primary hypogonadism (Female)?
Gonadal dysfunction
-Reduced oestrogen and progesterone production
- Turner’s syndrome (Gonadal Dysgenesis)
- Gonadal damage
- Primary ovarian failure
- PCOS
What is the karyotype of Turner’s syndrome?
45X0
What are the causes of secondary hypogonadism?
Kallman syndrome
Pituitary/hypothalamic tumour (Non-functioning or prolactinoma)
Hyperprolactinaemia
Functional - Hypothalamic amenorrhoea
-Low BMI, Excess exercise, stress
Contraceptive pill use - Negative feedback signal to reduce FSH and LH
What symptom is typically associated with Kallman syndrome?
Anosmia- Failed development migration of olfactory bundles
What are functional causes of hypothalamic amenorrhoea?
Low BMI
Excess exercise
Stress
What are the main causes of primary hypogonadism in Males?
Gonadal dysgenesis (Klinefelter’s syndrome, cryptochrodism)
Gonadal damage
Post-orchitis (Mumps)
What is the karyotype for Klinefelter’s syndrome?
47XXY
What are the secondary causes of hypogonadism in Males?
Kallman Syndrome
Pituitary/hypothalamic tumour
Hyperprolactinaemia
What are the features of hypogonadism?
Delayed puberty - Primary amenorrhoea, absent sexual characteristics (absent pubic hair, delayed thelarche, micropenis, high-pitched voice, small undescended testes)
Infertility
Low libido
Female specific - Night sweats/hot flushes
-Amenorrhoea
Erectile dysfunction
What is the first-line investigation in females presenting with symptoms of hypogonadism?
Pregnancy test
What investigations are performed in hypogonadism?
Pregnancy test LH/FSH Prolactin Testosterone/Oestradiol TFTs Karyotyping Pituitary MRI
What is the hormone profile in primary hypogonadism?
Hypergonadotrophic hypogonadism
- Raised LH/FSH/GnRH
Low tesosterone/oestrogen
What is the hormone profile in secondary hypogonadism?
Hypogonadotropic hypogonadism
What are the effects of growth hormone?
Increased blood glucose
Increased insulin resistance
Increased muscle growth
Increased bone thickness
What organs does GH have an effect on?
Bone
Muscle
Liver
Kidney
Releases IGF-1
Growth hormone causes the release of what?
Insulin-like growth factor-1 (Somatomedin)
What is the most common cause of acromegaly?
Pituitary adenoma of somatotrophs
What are the features of Acromegaly?
Coarse facial features Prognathism and large tongue Spade-like hands and large feet Excessive sweating Organomegaly Headache Visual disturbances Possible: Hyperprolactinaemia, hypopituitarism