Endocrinology

Question 1

Define Endocrinology

Answer 1

The study of hormones, action and interactions , and the medical conditions associated with deficient and excessive secretion.

Question 2

Define Hormone

Answer 2

A substance that is secreted by an endocrine gland and is transported in the blood to regulate the function of another tissue or gland.

Question 3

What are the main endocrine glands?

Answer 3

Pineal Gland
Pituitary Gland
Hypothalamus
Thyroid Gland
Thymus
Adrenal Gland
Pancreas
Ovaries
Testis

Question 4

What is the role of the hypothalamus?

Answer 4

Convert neurological signals to stimulatory hormones and is affected by sleep patterns and stress responses

Question 5

Describe the pituitary gland

Answer 5

Located in the base of the brain
Connected to Hypothal via pituitary stalk
Anterior and Posterior lobes
Stimulated by the hypothal

Question 6

What hormones are associated with the hypothal?

Answer 6

GHRH
Somatostatin
GnRH
TRH
CRH
Dopamine

Question 7

What hormones are associated with the anterior pituitary gland?

Answer 7

GH 
FSH
LH
TSH
ACTH
PROLACTIN

Question 8

Define Diurnal Variation

Answer 8

Due to the neuronal and sight stimulus required, hormones are often secreted in a pulsatile manner, with frequency and amplitude of pulse varying through out the day.

Question 9

What is Hypopituitarism?

Answer 9

Decreased secretion of the hormones produced in the pituitary gland

Question 10

What are the causes of Hypopituitarism?

Answer 10

Pituitary tumours
Brain tumours
Infection (TB, sarcoidosis)
Haemorrhage (Sheehan’s syndrome)
Autoimmune
Trauma

Question 11

Describe the steps following CRH release from the hypothal

Answer 11

1. Corticotrophin releasing hormone is released episodically from the hypothal
2. ACTH acts on the adrenal stimulating the adrenal cortex pathway
3. Cortisol is the main analyte produced
4. Negative feedback loop controls the pathway

Question 12

What is Cortisol involved in?

Answer 12

It promotes gluconeogenesis, glycogenesis and increased fatty metabolism.
It controls salt and water balance as well as blood pressure regulation

Question 13

What is the 9am reference range for cortisol?

Answer 13

200-600nmol/L

Question 14

What are the characteristics of Addison’s Disease?

Answer 14

Destruction of the adrenal cortex and disorders of steroid metabolism

Question 15

What are the clinical signs of cortisol deficiency?

Answer 15

Inability to mount a stress response to illness/trauma
Dizziness
Lethargy
Low BP

Question 16

How is cortisol deficiency diagnosed?

Answer 16

9am cortisol
Short Synacthen Test
ACTH
Urea/Electrolytes
Adrenal imaging

Question 17

What are the primary and secondary causes of Cushing’s Syndrome?

Answer 17

Primary:
Adrenal Tumours
Iatrogenic-Hydrocortisone administration

Secondary:
ACTH secreting tumours (pituitary and ectopic)

Question 18

What are the signs and symptoms of Cushing’s Syndrome?

Answer 18

Moonfaced
Increased abdominal fat
Buffalo hump
Thin skin leading to striation
Easy bruising
Muscle wasting
Hirsuitism
Hypertension
Glucose Intolerance

Question 19

How is Cushing’s Syndrome diagnosed?

Answer 19

Screening:
Urine free cortisol
Overnight dexamethasone suppression test
Salivary cortisol

Diagnostic:
ACTH
High dose Dexamethasone

Question 20

Describe the steps of HP-Thyroid

Answer 20

1. TRH acts on the thyrotrophs in the anterior pituitary causing the release of TSH
2. TSH acts on thyroid gland stimulating the production of T3/T4
3. A negative feedback loop controls the cycle

Question 21

What is the reference range for TSH?

Answer 21

0.3-5mU/L

Question 22

What are T3 and T4 responsible for?

Answer 22

Normal maturation and metabolism of all body tissues

Question 23

What is the reference range for free T4?

Answer 23

8-19pmol/L

Question 24

What is the reference range for free T3?

Answer 24

2-6pmol/L

Question 25

What are the signs and symptoms of hypothyroidism?

Answer 25

``` Tiredness, lethargy Weight gain Cold intolerance Raised cholesterol Inattention ```

Question 26

What are the primary and secondary causes of hypothyroidism?

Answer 26

Primary: Destruction of the gland (autoimmune) Congenital Defects Drugs (lithium/amiodarone) Secondary: Panhypopituitarism Isolated TSH

Question 27

What are the primary and secondary causes of hyperthyroidism?

Answer 27

Primary: Graves disease toxic goitre Thyroiditis Secondary: Exogenously administer iodine-containing drugs Excessive T4 and T3 ingestion TSHoma

Question 28

What are the signs and symptoms of hyperthyroidism?

Answer 28

``` Weight loss Sweating and heat intolerance Fatigue Palpitations Agitation and tremors Generalised muscle weakness Angina/ heart failure Diarrhoea Oligomenorrhoea/ subfertility Goitre Eye lid retraction and lid lay. ```

Question 29

How is hyperthyroidism diagnosed?

Answer 29

Serum TSH and Serum fT4 Serum fT3 Imaging of the pituitary.

Question 30

Describes the steps in HP-Prolactin

Answer 30

1. Controlled by inhibition of secretion 2. Dopamine is the principle factor 3. Prolactin self-regulates 4. Secretion seems to be stimulated by factors that suppress dopamine 5. It is affected by physiological factors such as lactation

Question 31

What are the causes of hyperprolactinaemia?

Answer 31

Primary: Prolactinoma Pituitary tumour ``` Other causes: Chronic renal failure Pregnancy Primary Hypothyroidism Drugs- antipsychotics Macroprolactin ```

Question 32

What are the signs and symptoms of hyperprolactinaemia?

Answer 32

``` Amenorrhea Galactorrhea/ gynaecomastia Oligospermia Impotence/ decrease sexual interest Visual Disturbance Headache Hypopituritarism ```

Question 33

How is hyperprolactinaemia diagnosed?

Answer 33

``` Prolactin Medical/ drug history Rule out macroprolactin Imaging Pituitary Hormones ```

Question 34

What is GH responsible for?

Answer 34

Lipogenesis Bone growth Protein synthesis Increase blood glucose and FFA production.

Question 35

What are the effects of GH excess and deficiency?

Answer 35

Deficiency: Hypoglycaemia in neonates Short stature in Children Difficult to detect in adulthood Increased growth: Acromegaly Gigantism

Question 36

How is GH excess/deficiency diagnosed?

Answer 36

``` GH dynamic function OGTT Insulin stress test IGF-1 Clinical examination ```