endocrine pathology COPY Flashcards
What is the main cause of acromegaly?
Increased secretion of GH from a pituitary adenoma (99%)
What is the male:female ratio of acromegaly and what is the UK incidence?
M:F
3 per million people/year
What are the symptoms of acromegaly?
low libido, headaches, pins and needles in extremities, joint pain, shoes no longer fit
What are the signs of acromegaly?
widely spaced teeth, macroglossia, prominent supraorbital ridge, massive growth of hands, feet and jaw
What are the complications of acromegaly?
impaired glucose tolerance and DM
Hypertension
Left ventricular hypertrophy
Increased risk of IHD, stroke and colon cancer
What are the diagnostic tests used to confirm acromegaly?
Oral glucose test - high glucose suppresses GH secretion. If the lowest GH recording is still above 1 microgram/litre = acromegaly
MRI scan of pituitary fossa
Look at old photos of patient
Visual fields and acuity examinations
What is the treatment for acromegaly?
Prevent tumour compression by excising the lesion
Reduce GH and IGF-1 by 1st line treatment = trans-sphenoidal surgery
somatostatin analogues = octreotide
GH antagonists = Pegvisomant
What is Cushing’s disease and syndrome
Increased glucocorticoid (cortisol) levels in the blood. chief cause = long term steroid use
What is Cushing’s disease caused by
Bilateral adrenal hyperplasia from an ACTH-secreting pituitary adenoma
What are the other causes of Cushing’s syndrome?
Ectopic ACTH production - small lung cancers and carcinoid tumours. Leads to pigmentation, weight loss, hyperglycaemia and hypokalemic metabolic alkalosis. Dexamethasone fails to suppress cortisol.
ACTH-independent causes (decreased ACTH due to negative feedback). Iatrogenic, adrenal adenoma. dexamethasone won’t suppress cortisol.
What are the symptoms of Cushing’s syndrome?
mood change, muscle weakness, weight gain, acne
What are the signs of Cushing’s syndrome?
Central obesity, moon face, buffalo hump, purple abdominal striae, osteoporosis
What are the diagnostic tests used to confirm Cushing’s disease and syndrome?
Measure free cortisol in 24hr urine test
overnight dexamethasone suppression test - dexamethasone suppresses ACTH production. if Cushing’s syndrome, there is no suppression
Check ACTH plasma levels - low=adrenal adenoma/carcinoma. high=Cushing’s disease –> inject dexamethasone to confirm
MRI scan of pituitary gland
CT scan of adrenal glands.
What is the treatment of Cushing’s disease and syndrome?
Treatment depends on cause
Iatrogenic = stop medications if possible
Cushing’s disease = surgical excision of pituitary tumour
Adrenal steroid inhibitors = metyrapone
Adrenal carcinoma –> radiotherapy
What is Conn’s syndrome and hyperaldosteronism?
pathophysiology
Excess production of aldosterone independent of the RAAS
Decreased potassium, increased sodium, increased BP
Aldosterone binds to receptors on the DCT of the nephron:
- stimulates sodium/potassium pumps on principle cells = more sodium in blood and more potassium in urine
- stimulates ATPase pump in alpha-intercalated cells = acidifies urine
What are the causes of primary hyperaldosteronism?
Conn’s syndrome = aldosterone-producing adenoma
Bilateral adrenocortical hyperplasia
What is the cause of secondary hyperaldosteronism?
Excess aldosterone production in response to high levels of renin
What are the symptoms of hyperaldosteronism?
Hypokalaemic signs - constipation, heart rhythm changes, muscle weakness, cramps
Headaches
What are the signs of hyperaldosteronism?
Hypertension
Hypernatremia
Metabolic alkalosis
What are the diagnostic tests used to confirm hyperaldosteronism?
U&E tests
Measure renin and aldosterone levels:
- low renin + high aldosterone = primary cause
- high renin + high aldosterone = secondary cause
How is hyperaldosteronism treated?
Conn’s syndrome = laparoscopic adrenalectomy, give spironolactone pre-operatively - potassium sparing diuretic. competitively binds to aldosterone receptors on principle cells and alpha intercalated cells of the DCT.
adrenal carcinoma = surgery
What is the epidemiology of Addison’s disease?
rare - 0.8/100,000
destruction of the adrenal cortex leads to cortisol and mineralocorticoid deficiency
what are the causes of Addison’s disease?
80% = autoimmune
TB, adrenal metastases, lymphoma, opportunistic infections in HIV
primary adrenal insufficiency = Addison’s disease
secondary adrenal insufficiency cause = iatrogenic - long term steroid use
What are the signs and symptoms of Addison’s disease?
lean, tanned, tired, anorexia, weakness, dizziness, nausea/vomiting
pigmented palmar creases and buccal mucosa
postural hypotension
What is the differential diagnosis of Addison’s disease?
viral infection or anorexia nervosa (potassium levels are decreased in anorexia but increased in Addison’s disease)
Diagnostic tests and results in Addion’s disease
decreased sodium and increased potassium levels - due to decreased mineralocorticoid
decreased glucose levels - due to decreased cortisol
Short ACTH stimulation test
21-hydroxylase adrenal autoantibodies are positive in autoimmune disease
What is the treatment of Addison’s disease?
replace steroids - hydrocortisone
mineralocorticoids to correct postural hypotension - fludrocortisone
What do beta cells produce?
insulin - decreases blood glucose levels
what do alpha cells produce?
glucagon - increases blood glucose levels
3 microvascular problems of hyperglycaemia?
retinopathy, neuropathy, nephropathy
3 macrovascular problems of hyperglycaemia
stoke, heart disease, limb ischaemia
WHO criteria - diagnosis of DM
symptoms of hyperglycemia = polyuria, polydipsia, unexplained weight loss, visual blurring
raised venous glucose - fasting>7, random>11
HbA1c>48mmol/l (6.5%)
Clinical presentations of DM
acute presentation = young person with short history of thirst, polyuria and unexplained weight loss
subacute presentation = older patients with same symptoms but less marked over time
retinopathy
type 1 DM = presenting with thirt, polyuria, weight loss
type 2 DM = complications generally seen
Type 1 DM cause
autoimmune destruction of beta cells by CD4 and CD8 T-lymphocytes
usually adolescent onset
patient must be given insulin
prone to ketoacidosis and weight loss
Treatment of T1DM
insulin, patient education
Type 2 DM cause
strongly related to obesity and insulin resistance
- initially the pancreas compensates for insulin resistance by increasing insulin secretion (hypertrophy and hyperplasia) - eventually beta cells suffer secretory exhaustion (atrophy) - insulin levels fall
High prevalence in Asians, elderly and men
onset is usually >40 years
stronger genetic influence than type 1 - twin studies
What are the other causes of DM?
drugs, pancreatic issues, Cushing’s disease, acromegaly, pregnancy
3 risk factors for type 2 DM
pregnancy, central adiposity, asian background, overweight/obese, >40 years of age, family history
Diagnostic tests for DM
fasting blood glucose = >7mmol/l
random blood glucose = >11mmol/l
Treatment of type 2 DM
first line = exercise and healthy diet
metformin - increases insulin sensitivity
sulfonylurea - increases insulin secretion = gliclazide