Endocrine Flashcards
Causes of Secondary HTN
Renal
Endocrine
Endocrine causes of Secondary HTN
- Cushing
- Conn syndrome
- Hyperthyroidism / Hyperparathyroidism
- Acromegaly
- Phaeochromocytoma
Phaeochromocytoma
Catecholamine producing tumour of adrenal medulla
Symptoms of phaeochromocytoma
Sweating
Palpitation
Weight loss
HTN
Ix for Phaeochromocytoma
I. 24 hour urine
- catecholamine levels or their metabolites (metanephrine)
- affected by drugs: eg. paracetamol, cough syrup, tricyclic antidepressant, beta blockers)
- sample needs to be collected in acid
II. Plasma metanephrine
- low specificity
- pts must be rested for 15-30 min
- affected by caffeine, alcohol, smoking
- only used as a secondary test
Conn’s syndrome definition
Excess aldosterone production
Leads to alkalosis / hypokalaemia
Causes of Conn’s syndrome
Primary - adrenal adenoma
Secondary - increased renin secretion
Ix for Conn’s syndrome
Plasma aldosterone:renin ratio
Pt must be rested > 30 mins
Primary = High aldosterone + Low renin
Secretions of anterior pituitary
TSH ACTH FSH LH GH Prolactin
Acromegaly
Excess GH secretion
Sx of Acromegaly
Sleep apnoea Protuding jaw HTN - Na retention Polyps Glucose intolerance Hypercalcaemia - increased Vit D
Ix for acromegaly
Basal IGF-1 (and GH)
Glucose tolerance test - GH should be suppressed < 1
Serum thyroid hormone forms
Bound > 99%
Free - active form
Sx of hypothyroidism
- Lethargy, tiredness
- Weight gain
- Cold intolerance
- Coarsening of hair + skin
- Slow reflexes, hoarseness
- Constipation
- Menstrual abnormalities
- Bradycardia
Mx of hypothyroidism
Thyroxin
Hyperthyroidism symptoms
- Weight loss
- Heat inttolerance
- Palpitations
- Agitation, tremor
- Muscle weakness
- Diarrhoea
- Thyroid eye disease
- Menstrual abnormalities
Hormones produced in adrenal gland
Adrenal cortex:
Aldosterone
Cortisol
Androgens
Adrenal medulla:
Catecholamines
Layers of adrenal gland
Zona glomerulosa - aldosterone
Zona fasiculatis and reticularis - cortisol + androgens
Daily cortisol production
25 mg/day
Functions of cortisol
Insulin antagonist
Glucogenesis
Protein catabolism
Immunosuppressant
Hypothalamo pituitary axis for cortisol release
CRH - Hypothalamus
ACTH - Anterior pituitary
Cortisol - Adrenal cortex
Addison’s disease definition
Primary adrenal insufficiency
Reduced cortisol and aldosterone
Sx of Addison’s disease
Hypoglycaemia
Hypotension
Hyperkalaemia
Skin hyperpigmentation
Ix for Addison’s disease
High ACTH + Low Cortisol
Short Synacthen test
Electrolytes
Short Synacthen test
250 micrograms synthetic ACTH IM
Normal people - cortisol rises > 420
Most common cause of Congenital Adrenal Hyperplasia (CAH)
21-hydroxylase deficiency
2 main types of CAH
Simple viralising
Salt wasting
Simple viralising CAH
Androgen affected
Male like symptoms
Salt wasting CAH
Aldosterone affected
Sx of Newborn CAH
- Ambiguous external genitalia
- Pigmented scrotum
- Salt wasting
- Sudden unexplained death (males)
Sx of Adult CAH
- Hirsutism
- Menstrual cycle disorder
- Subfertility
Ix for CAH
1) Blood:
17α hydroxy progesterone
Electrolytes
Glucose
2) Urine
- Electrolytes
- Steroid profile
Sx of Cushing’s syndrome
Mental disturbances Truncal obesity Striae Hyperandrogenism - hirsutism, amenorrhoea Glucose tolerance Sodium retention HTN Osteoporosis
Ix for Cushing’s
Dexamethasone suppression test
Low serum/salivary cortisol - false negatives
Dexamethasone suppression test
1) 1 mg overnight
9 am cortisal should be < 50 mmol/L
2) Low dose dexamethasone 6 hourly for 48 hrs
Cushing’s shows no suppression
Cushing’s disease
Pituitary dependent Cushing’s syndrome
ACTH is raised
Differentiating between primary and secondary Cushing’s syndrome
High dose dexamethasone
Primary - no suppression
Secondary - some suppression
Causes of Diabetes Insipidus
Cranial
Nephrogenic
Causes of Cranial Diabetes Insipidus
Idiopathic:
- Familial (autosomal dominant)
- Sporadic
Secondary:
- Trauma
- Tumours (craniopharyngioma, pituitary adenoma)
- Infections
- Autoimmune
Causes of Nephrogenic Diabetes Insipidus
Idiopathic
Secondary - drugs, metabolic, vascular
Drug causing Nephrogenic Diabetes Insipidus
Lithium
Vascular cause of Nephrogenic Diabetes Insipidus
Sickle cell disease
Metabolic cause of Nephrogenic Diabetes Insipidus
Hypercalcaemia
Hypokalaemia
How does Hypercalcaemia lead to Hypernatraemia
calcium interfers with vasopressin action, if high can be the cause of water depletion/dehydration
Water deprivation test
Diagnoses Diabetes insipidus if urine osmolarity does not increase
Differentiating test for cranial vs nephrogenic diabetes insipidus
Desmopressin
Action of loop diuretics
Block Na reabsorption in proximal tubule
Can cause hypokalaemia
Effect on acidosis on [K]
Acidosis leads to Hyperkalaemia
Actions of PTH
Bone resorption
Increases Ca reabsorption in kidney
Decreases PO4 reabsorption in kidney
Actions of 1,25dihydroxycholecalciferol
Vit D
increased Ca and PO4 absorption from GI and Kidney
Actions of Calcitonin
Bone mineralisation
Reduced Ca and PO4 reabsorption
Clinical use of calcitonin
Tumour marker
Therapeutic Rx of hypercalcaemia and Paget’s
Presentation of Hypercalcaemia
Bones, stones, abdo groans and psychic moans
Bone pain Renal calculi Constipation Abdo pain Confusion
ECG changes in hypercalcaemia
Shortened QT
Bradycardia
Funky causes of hypercalcaemia
Prolonged tourniquet
Sarcoidosis
Thiazide diuretics - increased Ca reabsorption
Rx of hypercalcaemia
Rehydration
Bisphosphonates
Steroids - for malignant disease
Hypocalcaemia presentation
Lethargy Tetany Cramps Cataracts Brittle nails/hair
ECG changes in hypocalcaemia
Prolonged QT
Arrhythmias
Hypocalcaemia treatment
Diet
Oral calcium supplementation
Oral vit D
IV calcium gluconate
Vit D deficiency in childern
Rickets
Vit D deficiency in adults
Osteomalacia
Causes of hypoparathyroidism
Surgery
Congenital - Di George syndrome
Mg deficiency - PTH resistance
Extracellular Ca distribution
50% free (ionised)
40% bound
10% complexed
Ovarian failure
Low oestradiol
Causes of primary ovarian failure
- Premature ovarian insufficiency
- Post menopausal
- Autoimmune damage
- Surgery
- Turners syndrome
Causes of secondary ovarian failure
LHRH deficiency - Kallman syndrome
Prolactinoma
Physiological causes of hyperprolactinaemia
Pregnancy
Drugs - dopamine antagonists
Role of dopamine on prolactin
Dopamine inhibits prolactin secretion
Pathological causes of hyperprolactinaemia
Prolactinoma
Acromegaly
Pituitary stalk lesions
Chronic renal failure
Presentation of Polycystic Ovarian syndrome (PCOS)
Oligo / Amenorrhoea Obesity Insulin resistance Hirsutism Oestrogenisation Increased CVS risk
Endocrine levels in PCOS
High LH
Normal FSH
Lab test changes during pregnancy
Increased:
- ALP
- GFR
Decreased:
- Albumin
- Creatinine
- Fasting BG
Hormone changes in pregnancy
Increased:
- Oestrogen
- Progesterone
- Prolactin
- hCG
Decreased:
- LH
- FSH
Complications of pregnancy
Gestational diabetes
HTN / Pre-eclampsia
Obstetric cholestasis
Pregnancy related liver diseases
Pre-eclampsia HELLP Hyperemesis Gravidarum Acute Fatty Liver of pregnancy Obstetric cholestasis
HELLP syndrome
Haemolysis
Elevated Liver enzymes
Low Platelets
Obstetric cholestasis
Usually 3rd trimester
Generalised pruritis
Biochemistry findings of obstetric cholestasis
Serum bile acids
Raised ALT and AST
ALP and Bilirubin usually normal
Site of LH action
theca and
mature granulosa cells
Site of FSH action
follicular
granulosa cells
Phases of menstrual cycle
Follicular phase
Luteal phase
Follicular phase of menstrual cycle
- Follicles recruited
- FSH makes it grow
- Oestrogen production
- Rise in oestrogen causes LH release
- LH ruptures follicle
Luteal phase of menstrual cycle
Corpus luteum carries on producing progesterone
Ix for infertility
LH/FSH Prolactin TFT Testosterone Oestradiol
Ovulation day in menstrual cycle
~ day 21
Assessment of ovulation
Progesterone level:
1) > 30 - normal ovulation
2) < 30 - reduced conception rate
3) low level, repeat next cycle
Role of FSH in males
stimulates sertoli cells to produce spermatozoa
Role of LH in males
stimulates Laydig cells to produce testosterone
Causes of male infertility
Hypergonadotrophic hypogonadism
Hypogonadotrophic hypogonadism
Obstructive azoospermia
Early signs of pre-eclampsia
HTN
Raised urate
Late signs of pre-eclampsia
Raised urea and creatinine
Low GFR
Proteinuria
Oedema