Endocrinology Flashcards
Hormones released from adrenal
Cortisol (zona fasciculata cortex)
Androgens (zona reticularis cortex)
Aldosterone (zona glomerulosa cortex)
Epinephrine (Chromaffin cells Medulla)
Dopamine (Chromaffin cells Medulla)
Norepinephrine (Chromaffin cells Medulla)
Where is cortisol released from?
Zona fasciculata cortex
Where are androgens released from?
Zona reticularis cortex
Where is aldosterone released from?
Zone glomerulosa cortex
Hormones released from thyroid
T3 (Epithelial cells)
T4 (Epithelial cells)
Calcitonin (parafollicular cells)
Hormones from hypothalamus
Growth hormone releasing hormone
Gonadotrophin releasing hormone
Thyrotropin-releasing hormone
Corticotropin-releasing hormone
Oxytocin
Vasopressin
Somatostatin
Vasopressin
Where are oxytocin and ADH (vasopressin) synthesized?
Supraoptic and Periventricular nuclei of the hypothalamus
Hormones from Pituitary (anterior)
Growth Hormone
TSH
Prolactin
ACTH
FSH
LH
Hormones from pituitary (posterior)
Releases ADH & Oxytocin (synthesised by hypothalamus)
Hormones from Placenta
Progesterone
hCG (Syncytiotrophoblast)
hPL (Syncytiotrophoblast)
Hormones from pancreas
Glucagon (alpha cells)
Insulin (beta cells)
Somatostatin (delta cells - note also produced by pylorus)
gamma cells secrete pancreatic polypeptide
Hormones from gastrointestinal tract
Gastrin (Stomach G cells)
Somatostatin (Stomach D cells)
Histamine (StomachECL cells)
Secretin (S cells duodenum)
Cholecystokinin (I cells duodenum)
Hormones from liver
Insulin like growth factors
Thrombopoietin
Angiotensinogen and angiotensin
Hormones from ovary
Oestragens
Progesterone
Androgen (theca cells)
AntiMullerian Hormone (Granulosa cells)
Hormones from pregnant uterus
Prolactin (Decidual cells)
Relaxin (Decidual cells)
Hormones from adipose tissue
Leptin
Small amounts Progesterone
Estrone
Hormones from kidney
Renin (granular cells of the juxtaglomerular apparatus)
Erythropoietin (Extraglomerular mesangial cells)
Thrombopoietin
Autosomal Dominant
Tuberous Sclerosis
Von Willebrand
Adult PKD
Huntingtons
Marfans
Neurofibromatosis
Noonans
Autosomal recessive
Cystic Fibrosis
Haemochromatosis
Infantile PKD
Thalassemia
Wilson’s Disease
X-Linked Dominant
Fragile X
Rett Syndrome
Vitamin D resistant Ricketts
X-Linked Recessive
Duchenne Muscular Dystrophy
Red/Green Colour Blindness
G6PD deficiency
Haemophilia
Most common cause of hypothyroidism worldwide?
Iodine deficiency
In UK: 90% of cases of hypothyroidism are autoimmune or iatrogenic.
Pheochromocytoma accounts for what percentage of cases of hypertension?
0.1%
- neuroendocrine tumour of the medulla of the adrenal glands that secretes high amounts of catecholamines.
Interpretation of hepatitis serology:
HBsAg = Indicates current infection either acute or chronic
Anti HBs = Indicates immunity either due to infection or vaccination
Anti HBc = Indicates either current or past infection
IgM Anti HBc = Indicates recent infection
What is responsible for the formation of Angiotensin 1 from Angiotensinogen?
Renin
What is the normal arterial pH range for fetal cord sample?
7.26-7.30
Threshold pH for adverse neurological outcomes 7.1
How much testosterone is bound to SHBG?
The binding constant of SHBG for testosterone is 3 times that of estrogen. Because of the higher concentrations of SHBG and the lower concentration of testosterone in the female, only 1% of testosterone is free (compared with 2% in the male).
In women: 60% to SHBG and 39% to albumin
In men: 60% is bound to SHBG and 38% to albumin
What is the most common cause of hyperprolactinaemia?
Primary hypothyroidism.
Other common causes include neuroleptic medication and dopamine D2 receptor anti-emetics.
How much testosterone is free?
Male 1.5-3% and female approx 1%.
Causes of Low Sex Hormone Binding Globulin
Androgens (inc anabolic steroids)
PCOS
Hypothyroidism
Obesity
Cushing’s syndrome
Acromegaly
Causes of High Sex Hormone Binding Globulin
Oestrogens e.g. oral contraceptives
Pregnancy
Hyperthyroidism
Liver cirrhosis
Anorexia nervosa
Drugs e.g. clomid, anticonvulsants
Acromegaly features:
Acromegaly Features
Elargement of the hands, feet, nose, lips and ears.
Skin thickening
Generalised soft tissue swelling of internal organs including the heart.
Deepening of voice and slowing of speech
Skull enlargement with frontal bossing
Mandibular protrusion (prognathism)
Macroglossia (enlargement of the tongue)
What are the causes of raised prolactin?
Hypothyroidism
Chronic renal failure
Liver disease
Pregnancy
Stress
Lactation
Chest wall stimulation & surgery
Acromegaly
PCOS
What drugs cause raised prolactin?
Opiates, H2 antagonists e.g. Ranitidine, SSRI’s e.g. Fluoxetine, Verapamil, Atenolol, some antipsychotics e.g risperidone and haloperidol, Amitriptyline, Methyldopa
What is WHO Type 1 ovulation disorder?
WHO type I hypo-gonadotropic, hypo-estrogenic, (15%)
- Causes: Damage to the pituitary gland or hypothalamus from surgery, injury, tumor, infection, or radiation
- High doses or long-term use of opioid or steroid (glucocorticoid) medicines
- Nutritional problems (both rapid weight gain or weight loss)
- hypothalamic pituitary failure
What is WHO Type 2 ovulation disorder?
WHO type II normo-gonadotropic, normo-estrogenic, (80%)
PCOS
What is WHO Type 3 ovulation disorder?
hyper-gonadotropic, hypo-estrogenic (5%)
Ovarian failure
What are the healthy adult hemoglobins?
-Adult haemoglobin (HbA) is made of 2 alpha globulin chains and 2 beta globulin chains and accounts for 97% of total haemoglobin in a normal adult.
- HbA2 is a normal variant of hemoglobin A that consists of two alpha and two delta chains
What is the fetal hemoglobin?
- Fetal haemogobin (HBF) is the main haemoglobin type in the fetus and persists after birth for around 6 months. Fetal hemoglobin is composed of two alpha and two gamma subunits
What chromosome defect causes Alpha Thalassemias?
Chromosome16 defects
What chromosome defect causes beta Thalassemias?
Chromosome 11
What chromosome defect causes beta Thalassemias?
Chromosome 11
What is the definition of Addison’s disease?
- in Addison’s both glucocorticoid and mineralocorticoid hormones are deficient.
- The main mineralocorticoid is Aldosterone.
- Cortisol (hydrocortisone) is the main glucocorticoid.
- Primary Addison’s: autoimmune adrenalitis being the most common.
- Secondary adrenal insufficiency causes: deficient ACTH production by the pituitary
- Tertiary causes: deficient CRH production by the hypothalamus
Biochemical features of Addison’s?
Hyponatremia
Hyperkalemia
Hypoglycemia
Hypercalcemia
Metabolic acidosis
Hypotension
Ductal Morphogenesis by which hormones?
Ductal Morphogenesis is stimulated by Oestrogen and Growth Hormone.
Alveolar morphogenesis by which hormones?
Progesterone, Prolactin and hPL.
Biochemistry in menopause
- Raised FSH > 30
- Low progesterone
Ovarian Corpus Luteum Theca Cells
- Small luteal cells (theca lutein cells)
- Androgen (Androstenedione) production
- Thecal Lutein cells produce progesterone from cholesterol
Ovarian Corpus Luteum Granulosa Cells
- Large luteal cells (granulosa luteal cells)
- Convert androgen to estradiol via aromatase
Granulosa Lutein cells produce progesterone
Roles of LH + FSH in ovarian hormone secretion
- FSH stimulates Aromatase production in the granulosa cells
- LH stimulates Androgen production in the theca (interna) cells
- LH also stimulates the contraction of the smooth muscle cells of the theca externa. This increases intrafollicular pressure which results in rupture of the mature oocyte.
How is progesterone produced in the ovary?
Synthesized from cholesterol by luteal cells.
What are concerning characteristics of decelerations?
- lasting >60 seconds,
- reduced baseline variability within the deceleration
- failure to return to baseline
- biphasic (W) shape
- no shouldering
What stimulations and inhibits TSH?
Inhibits: somatostatin
Stimulates: hypothalamic thyrotropin-releasing hormone
Ultrasound findings consistent with miscarriage:
- Mean gestation sac diameter >/= 25mm (with no obvious yolk sac)
- With a fetal pole: crown rump length >/=7mm & without evidence of fetal heart activity.
Ultrasound findings consistent with complete molar pregnancy:
- Solid collection of echoes with numerous small (3-10 mm) anechoic spaces (snowstorm or granular appearance).
- Bunch of grapes’ sign which represents hydropic swelling of trophoblastic villi
- Enlarged uterus
Ultrasound findings consistent with partial molar pregnancy:
- Fetus with severe structural abnormalities, growth restriction, oligohydramnios or a deformed gestational sac may be noted.
- Colour Doppler may show high velocity, low impedance flow
- Placenta enlarged containing areas of multiple, diffuse anechoic lesions
Look at spirometry chart and identify lung volumes
Spirometry chart
Fetal Blood Sampling:
Indications for FBS
1. Pathological CTG in labour (cervix dilated >3 cm)
2. Suspected acidosis in labour (cervix dilated >3 cm)
Contraindications:
Maternal infection e.g HIV, HSV and Hepatitis
Known fetal coagulopathy
Prematurity (< 34 weeks gestation)
Acute fetal compromise
Interpretation of FBS results:
> 7.25 Normal Repeat in 1 hour if CTG remains abnormal
7.21 to 7.24 Borderline Repeat in 30 minutes
<7.20 Abnormal Consider delivery
Classification of variability on CTG:
Non-reassuring:
- <5 for 30-50 mins
- >25 for 15-25 mins
Abnormal:
<5 for >50mins
>25 for > 25 mins
Main inhibitors of prolactin:
dopamine and somatostatin
Mineralocorticoid
- The primary endogenous mineralocorticoid is Aldosterone
- Progesterone is another important example
- Synethetic example: fludrocortisone
- Inhibitors: Spironolactone and Eplerenone
Glucocorticoid
The primary endogenous glucocorticoid is Cortisol
Prednisolone, Dexamethasone and Betamethasone are examples
Biochemical features of Addison’s?
Hyportension
Hypernatreamia
Hypokaelamia
Ultrasound frequencies are sound waves with frequencies of
above 20 kHz.
Intracellular fluid:
Intracellular fluid 40% of body weight
Extracellular fluid
Extracellular fluid 20% of body weight
ECF comprises plasma and interstitial fluid
Plasma volume typically around 3 litres (5% of body weight)
Glucagon Inhibitors
Somatostatin
Insulin
Uraemia
Increased free fatty acids and keto acids into the blood
Glucagon Stimulants
Hypoglycemia
Epinephrine
What does glucagon do?
Stimulates Glycogenolysis (breakdown glycogen to glucose) and Gluconeogenesis (formation glucose from amino acids)
Inhibits glycolysis (conversion glucose into pyruvate)
Conn’s Syndrome
primary hyperaldosteronism
- Main causes: adrenal hyperplasia (65%) and adrenal adenoma
- Secondary causes: renal artery stenosis or a renin producing tumour (increased renin)
Biochemical markers:
hypertension, hypernatremia, hypokalemia
What makes a deceleration non-reassuring?
Non-Reassuring
Early deceleration
Variable Deceleration
Single prolonged deceleration <3mins
What makes a deceleration abnormal?
Atypical variable Decelerations
Late Decelerations
Single prolonged deceleration >3mins
Atypical features:
- lasting >60 seconds,
- reduced baseline variability within the deceleration
- failure to return to baseline
- biphasic (W) shape
- no shouldering
RMI Type 1 Scoring
Ca-125 value
Menopause 1 = pre-menopausal; 3 = post-menopausal
Ultrasound features:
multi-locular cyst
solid areas
ascites
intra-abdominal mets
0 = no ultrasound features
1 = 1 ultrasound features
3 = 2 or more ultrasound features
Which part of the ovary is responsible for androgen production?
Theca cells. Luteneising hormone drives the conversion of cholesterol into androgens in the theca cells. These androgens are then transferred to the granulosa cells for conversion (aromatisation) into estrogen (estradiol) under the influence of follicle-stimulating hormones.
What is the endocrine response to low serum calcium levels?
Increased parathyroid hormone, increased calcitriol and decreased calcitonin
Calcitonin is produced by the parafollicular cells of the thyroid gland in response to high calcium levels.
glucocorticoids are secreted by
zona fasciculate
androgens are secreted by
zona reticularis
With regard to the renin-angiotensin system, where are the juxtaglomerular cells located?
Afferent arteriole in the kidney
Renin is secreted from the juxtaglomerular cells in response to a decrease in arterial blood pressure (detected by the baroreceptors), a decrease in sodium chloride (detected by the macula densa) and the sympathetic nervous system.
Which hormone has a structure similar to growth hormone?
Growth hormone is structurally similar to prolactin and human placental lactogen.
Which of the following is the most reliable test for the diagnosis of Cushing syndrome?
The answer is Dexamethasone suppression test. A 24-hour urine sample to detect cortisol can be used for outpatients; however, a suppression test is more reliable.
Which hypothalamic hormone stimulates the release of prolactin?
Thyrotrophin-releasing hormone stimulates the release of TSH and prolactin from the anterior pituitary.
Dopamine inhibit prolactin.
Adrenomedullary hypersecretion is caused by which condition?
Phaeochromocytoma. Adrenomedullary hypersecretion is caused by catecholamine-secreting tumours. It is characterised by hypertension, pallor, headache and sweating and glucose intolerance.
Which hormone is responsible for the ovulation and initiation of luteinisation of the follicle?
The answer is Luteinising hormone (LH). Circulating estrogen levels rise in the follicular phase and are responsible for the preovulatory surge of LH. This then triggers the ovulation and initiates the luteinisation. Progesterone may have some role in the LH surge, but the main factor is LH, which is responsible for the above actions.
The blood test of a 36-year-old fertility patient shows elevated luteinising hormone (LH) levels and high estradiol levels. What is the most likely cause of this?
Midcycle LH surge
Polycystic ovary syndrome biochemical markers:
Polycystic ovary syndrome (PCOS) is associated with high LH levels and usually normal estradiol levels.
PCOS results in a ratio of LH/Follicle-stimulating hormone (FSH) > 1. The blood test may have been taken midcycle. In this case we are not able to diagnose PCOS because we do not have a value for FSH. Generally, women with PCOS have normal estradiol levels.
Ovarian failure biochemical markers:
Ovarian failure will result in high LH levels but low estradiol levels.
Hypogonadotrophic hypogonadism and weight-related amenorrhoea biochemical markers:
low LH levels and low estradiol levels.
Which hormone is made in the ovarian granulosa cells before ovulation occurs?
Anti-müllerian hormone
In the granulosa cells of the ovarian follicle, follicular stimulating hormone up-regulates the enzyme which converts androstenedione to estrone.
What enzyme converts androstenedione to estradiol?
CYP19 aromatase
What is the primary treatment of hyperthyroidism in pregnancy?
Propylthiouracil
What is the definition of premature menopause?
Menopause before 40 years of ag
What is the definition of puberty in females?
Individual becomes capable of sexual reproduction
Which three hormones have an identical alpha-subunit to hCG?
luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH)
What hormone is secreted by acidophil cells in the anterior pituitary?
growth hormone
What hormone is significantly increased on day 0 of the menstrual cycle?
FSH
A woman is scanned on account of bleeding at 8 weeks’ gestation. The scan shows a viable pregnancy with a corpus luteum on the left ovary.
Which hormone is responsible for maintaining the corpus luteum in early pregnancy?
The placenta secretes human chorionic gonadotrophin which signals the corpus luteum to continue progesterone secretion. Progesterone maintains the thick endometrial lining.
What is the finite life span of the corpus luteum?
14 days
The peak in LH level at about day 14 of the cycle induces resumption of the first meiotic division of the primary oocyte, producing the secondary oocyte. Ovulation is a direct result of the LH surge.
How many hours after the LH surge does ovulation occur?
12
Ovulation is a direct result of the LH surge and occurs some 12 h after the peak of LH values.
Where in the body is calcidiol produced?
Liver
n the first trimester, the pregnancy is sustained by human chorionic gonadotrophin (hCG), which is produced from about 7 days post-fertilisation.
Where is hCG produced?
Syncytiotrophoblast
In humans, human chorionic gonadotrophin (hCG) is secreted by the syncytiotrophoblast from as early as 6–7 days post-fertilisation.
The levels of hCG in maternal serum and urine rise rapidly in early pregnancy, peak at about 12 weeks of gestation and then decline.
