Endocrine Flashcards
True/False: insulin inhibits ketogenesis
True
What are PPAR (peroxisome proliferator activated receptor) gamma?
PPAR gamma is an intra-cellular receptor that is activated by free fatty acids (natural endogenous ligands)
What is the clinical significance of PPAR (peroxisome proliferator activated receptor) gamma?
Give an example of a drug that is a PPAR gamma agonist.
- Implicated in the pathology of obesity, diabetes, atherosclerosis and cancer.
- PPAR gamma agonists used in the treatment of hyperlipidaemia and hyperglycaemia.
- Thiazolidinediones (e.g. pioglitazone) are PPAR gamma AGONISTS that are insulin sensitising drugs used in DM.
A drug is described as insulin-sensitising. What does this mean? Give an example.
Lowers serum glucose level without increasing pancreatic insulin secretion.
Thiazolidinediones (e.g. pioglitazone)
What diuretic may be useful in the treatment of acute hypercalcaemia?
Frusemide.
Patient has tertiary hyperparathyroidism and is unfit for surgery. What drug may be offered?
Cinacalcet - calcimimetic that stimulates the calcium sensing receptor to reduce PTH secretion.
Patient has secondary hyperparathyroidism from CKD with elevated PTH. What drug may be offered?
Cinacalcet - calcimimetic that stimulates the calcium sensing receptor to reduce PTH secretion.
When should a patient with primary hyperparathyroidism be offered parathyroidectomy surgery (4 conditions)?
- Significant hypercalcaemia/hypercalciuria
- Impaired renal function
- Osteoporosis
- Age less than 50 years
What is the MOA of dapaglifozin?
Common SE of this drug?
Sodium-glucose-cotransporter 2 inhibitor.
SE: glycosuria
Give an example of:
- PPAR-alpha agonist
- PPAR-gamma agonist
- PPAR-alpha agonist = fibrates
2. PPAR-gamma agonist = thiozolidinediones
Name one fibrate class drugs ‘without’ fibrate in the name.
The rest will contain ‘fibrate’ somewhere in name
Gemfibrozil
Patient with DM on long-term metformin is noted to have mild anaemia that is macrocytic. What is the problem?
Metformin induced B12-deficiency associated with raised homocyteine levels.
Occurs in 30% of patients on Metformin and often misdiagnosed as DM neuropathy.
What has happened to the incidence of type 1 DM in the 20 years.
Doubled - reason unclear.
What is the typical histology of Grave’s disease?
- follicular hyperplasia
- intracellular colloid droplets
- lymphocytic infiltration
An immobile long-stay patient in hospital for epilepsy treated with phenytoin and carbamazepine with a background of RA on prednisone is placed on heparin DYT prophylaxis.
What condition is the patient at-risk of developing?
Osteoporosis.
Phenytoin, carbamazepine, prednisone and heparin can ALL cause osteoporosis.
What are the 5 effects of GH?
Clue: growth PILES
PILES:
- Protein synthesis
- Insulin sensitivity decreased (ANTI-insulin)
- Lipolysis
- Epiphyseal growth
- Sodium retention
T/F: Subacute thryroiditis does NOT cause increased uptake in a radiouptake iodine scan.
True.
SIADH has what findings in the following parameters:
Serum osmolality Urine osmolality Urine sodium Fluid status Fractional sodium excretion
Serum osmolality - decreased
Urine osmolality - greater than 100 mOsm/kg
Urine sodium - greater than 30
Fluid status - euvolemia
Fractional sodium excretion greater than 1%
What is carbergoline?
D2-receptor agonist - treatment of prolactinomas
T/F: Paget’s disease is usually symptomatic.
False.
Most cases o Paget’s disease is asymptomatic.
Which cell line is abnormal in the pathophysiology of Paget’s disease?
What is the consequence of this abnormality.
Osteoclast - accelerated bone turnover and abnormal bone remodelling.
What is a rare but fatal complication of Paget’s disease?
Osteosarcoma.
What is a benign complication of Paget’s disease?
Giant cell tumours.
Which of the following are elevated in Paget’s Disease:
- serum ALP
- bone-specific ALP
- serum calcium
- serum phosphate
- serum ALP - normal or raised
- bone-specific ALP - RAISED
- serum calcium - often normal
- serum phosphate - often normal
What type of imaging is useful in Paget’s Disease?
Plain XR - to reveal impending fractures
Radionucleotide bone scan - reveals active disease, more useful in early disease.
Which cytokines promote osteoclast differentiation (2)?
Which cytokine inhibits osteoclast differentiation (1)?
Promotors of osteoclast differentiation:
- RANKL (Receptor activator of nuclear factor kappa-B ligand)
- mCSF (macrophage colony-stimulating factor)
Inhibitors of osteoclast differentiation:
- OPG (osteoprotegerin)
What is osteoprotegerin (OPG)?
- Soluble decoy receptor for RANKL
- Inhibits osteoclast differentiation
When is treatment of Paget’s Disease indicated?
- Symptomatic patients with elevated ALP should be treated.
- Asymptomatic patients:
- elevated ALP requires treatment
- normal ALP should be treated if bone scan suggests active disease
What treatment of Paget’s Disease in the following scenarios?
- Young patient with less extensive disease (1st line therapy)
- Elderly patients with extensive disease
- Intolerant of 1st line therapy (i.e. 2nd line therapy)
- Young patient with less extensive disease
- nitrogen-based bisphosphanate (IV or PO) - Elderly patients with extensive disease
- zolendronic acid - Intolerant of 1st line therapy (i.e. 2nd line therapy)
- calcitonin
In patients treated with Paget’s Disease with nitrogen-based bisphosphonate, what should be tested and supplemented to avoid hypocalcaemia?
- Test normal serum levels of calcium and 25-hydroxy vitamin D (calcidiol)
- Supplement with vitamin D (800 international units daily) and calcium supplements (1200 mg/day of elemental calcium)
Comment about the following in MODY (Mature-Onset Diabetes of the Young) due to a glucokinase mutation (MODY 2):
- Fasting glucose level
- Insuline secretion
- Risk of macrovascular complications
- Treatment
- Fasting glucose level - high BSL
- Insuline secretion - decreased
- Risk of macrovascular complications - low risk
- Treatment - diet-controlled
MODY 3 is the most common type of MODY, comment on the following:
- What is the frequency within the MODY population?
- Which gene is involved?
- What is the pathophysiology?
- Other associated features?
- Treatment?
MODY 3:
- Frequency: 30-50%
- Gene: HNF1A (hepatic nuclear factor 1 alpha)
- Pathophysiology: Beta-cell dysfunction
- Associated feature: glycosuria
- Treatment: sulfonylurea
MODY 2 is the SECOND most common type of MODY, comment on the following:
- What is the frequency within the MODY population?
- Which gene is involved?
- What is the pathophysiology?
- Other associated features?
- Treatment?
MODY 2:
- Frequency: 15-20%
- Gene: Glucokinase
- Pathophysiology: Beta-cell SENSING dysfunction
- Associated feature: fasting hypergycaemia
- Treatment: diet control
Regarding sulfonylureas:
- Give MOA
- Give 4 examples
- Increase insulin secretion
2. gliclazide, glipizide, glibenclamide, glimepiride
Sulfonylureas can cause hypoglycaemia, especially in the elderly.
Which 2 are more prone to causing hypoglycaemia and hence which 2 are preferable in treating the elderly T2DM patient?
- Avoid (long-acting) glibenclamide or glimepiride
- Consider (shorter-acting) gliclazide or glipizide
NB: long-acting have more syllables (4 vs 3)!
T/F: the pathophysiology of the 4 most common types of MODY involve Beta-cell dysfunction.
True.
T2DM is a common condition.
What are the treatment targets for the following parameters in a T2DM patient:
- HDL cholesterol
- Total cholesterol
- Triglycerides
- BP target
- HDL cholesterol - greater than 1 mmol/L
- Total cholesterol - less than 4 mmol/L
- Triglycerides - less than 2 mmol/L
- BP target - less than 130/80 mmHg
T2DM is a common condition.
What are the treatment targets for the following parameters in a T2DM patient prone to HYPOGLYCAEMIA:
- HbA1c
- fBSL
- HbA1c - less than 8%
- fBSL - 6-8 mmol/L
NB: more relaxed ranges.
T2DM is a common condition.
What are the treatment targets for the following parameters in a T2DM patient NOT prone to hypoglycaemia:
- HbA1c
- fBSL
- HbA1c - less than 7%
- fBSL - 4-6 mmol/L
NB: more aggressive ranges.
T2DM is a common condition.
What is the LDL-C treatment targets for a T2DM patient also diagnosed with hypercholesterolaemia.
SECONDARY prevention: LDL-C less than 1.8 mmol/L (more strict)
T2DM is a common condition.
What is the LDL-C treatment targets for a T2DM patient WITHOUT a diagnosis of hypercholesterolaemia.
PRIMARY prevention: LDL-C less than 2 mmol/L (less strict)
What are the 2 main pathophysiological mechanisms for diabetes.
- Insulin insufficiency (Type 1)
- Insulin resistance (Type 2)
NB: may be a combination of the above
PCOS is a diagnosis of exclusion.
Which 6 conditions should be excluded prior to considering a diagnosis of PCOS?
C-C-CAP T:
Cancer (androgen secreting tumours) Cushing's syndrome Congenital adrenal hyperplasia Acromegaly Prolactinaemia (hyperprolactinaemia) Thyroid dysfunction
What is the Rotterdam criteria for diagnosis of PCOS?
Need 2 out of 3 of the following:
- Oligo/anovulation (menstrual disturbance)
- Hyperandrogenism (clinical or biochemical)
- Polycystic ovaries (on ultrasound)
Hyperandrogenism:
Clinically: hirsutism
Biochemically: raised FAI or free testosterone
What are the 2 biochemical features of hyperandrogenism?
Which of these is more useful in PCOS?
Raised FAI (free androgen index) or free testosterone
What is the free androgen index (FAI) ratio?
How does obesity affect this ratio?
FAI = 100 x [total testosterone / SHBG]
SHBG is reduced in obesity leading to increased FAI. FAI correlated more with obesity than PCOS.
NB: SHBG = sex hormone binding globulin
What are the DDx of Cushing’s syndrome?
Endogenous:
- Pituitary tumour (secrete ACTH) - 70%
- Adrenal tumour (secrete cortisol) - 15%
- Ectopic (secrete ACTH) - 15%
Exogenous glucocorticoids
Pituitary tumours that cause Cushing’s syndrome are referred to as Cushing’s disease. What are the 3 DDx?
- Microadenoma
- Macroadenoma
- Hyperplasia
What are 2 DDx for ectopic causes of Cushing’s syndrome?
Paraneoplastic Cushing’s syndrome:
- Carcinoid tumour
- Small cell lung cancer (SCLC)
What endogenous source of Cushing’s syndrome (i.e. pituitary, adrenal or ectopic) is suggested with a low or undetectable DHEA-S (dehydroepiandrosterone sulphate)
Adrenal Cushing’s Syndrome.
You suspect a patient may have Cushing’s syndrome.
What 3 tests (and their positive results) may be useful to elucidate?
- Evening salivary cortisol (11pm)
- 24h urinary free cortisol
- Overnight 1mg DST (dexamethasone suppression test)
For the ‘overnight 1mg DST’ used to confirm Cushings disease, give the values for:
- Negative test
- Equivocal test
- Positive test
- Negative test - less than 1.8 ug/dL
- Equivocal test - 1.8-7.5 ug/dL
- Positive test - greater than 7.5 ug/dL
A patient suspected of Cushing’s syndrome has initial tests that are equivocal for Cushing’s syndrome, with repetition of several tests suggesting the same equivocal results.
Which 2 furthers tests may be used to elucidate?
- Overnight 2mg DST (high dose)
2. DST-CRH (dexamathasone-corticotrophin-releasing hormone test)
Empaglifozin is used in the treatment of T2DM.
What is the MOA?
May it be used as a monotherapy or only an add-on OHG?
MOA:
- SGLT2 inhibition (sodium-glucose cotransporter 2)
- Leads to glycosuria
May be used as a monotherapy OR an add-on OHG.
Where is SGLT2 located in the nephron and what is it’s responsibility?
SGLT2 is in the PT and is responsible for 60% of renal glucose reabsorption.
Regarding Empagliflozin, comment on the following:
- Does is cause weight loss?
- Does it reduce BP?
- Does it cause hypoglycaemia when used as monotherapy?
- may cause 2-3kg weight loss that plateaus at 6m
- Reduces BP modestly by 1-5mm Hg
- Does NOT cause hypoglycaemia
What complication should be considered when using Empagliflozin for women with T2DM that are post-menopausal?
8x risk of genitourinary infections due to glycosuria.
Which of the new OHG decreases both cardiovascular mortality AND slow nephropathy progression?
Empagliflozin
The ‘Gliptins’ or DPP4 inhibitors (Dipeptidyl peptidase-4 inhibitors) are used in the treatment of T2DM.
What is the MOA?
- DPP-4 enzyme INACTIVATES incretins (GLP-1, GIP)
- Incretins usually have 2 effects:
- Stimulate insulin release
- Inhibit glucagon release
- This leads to lowering of blood glucose
- DDP-4 inhibition therefore leads to the prolonged effects of incretins.
The endocrine pancreas has the following 5 cells within the islet of Langerhans, what proportion of this parenchyma do they occupy and what do they secrete?
- Alpha-cell
- Beta-cells
- Delta-cells
- Epsilon-cells
- Gamma-cells
- Alpha-cell (20%) secrete glucagon
- Beta-cells (70%) secrete insulin (and amylin)
- Delta-cells (5%) secrete somatostatin
- Epsilon-cells (4%) secrete ghrelin
- Gamma-cells (1%) secrete pancreatic polypeptide
What are the 3 functions of incretins?
Post-prandial hormones that:
- Stimulate insulin release from pancreatic beta-cells
- Inhibit glucagon release from pancreatic alpha-cells
- Reduce gastric emptying and slows rate of nutrient absorption
Name 2 incretins and which cells secrete them.
Incretins are secreted by gut cells:
K-cells secrete GIP (gastric inhibitory peptide)
L-cells secerete GLP-1 (glucagon-like peptide-1)
Which 4 OHGs used in T2DM are beneficial (or neutral) with respect to CV outcomes?
MAPS:
Metformin
Acarbose
Pioglitazone (thiazolidinedione)
SGLT2 inhibitor
Which 3 OHGs used in T2DM are unfavourable with respect to CV outcomes?
Rosiglitazone
Sulfonylureas
Which class of OHGs are unfavourable in a T2DM with CCF?
Thiazolidinediones