Endocrinology Flashcards
(113 cards)
What is sick euthyroid syndrome?
The sick euthyroid syndrome often occurs in individuals suffering from a systemic illness such as a myocardial infarction. The condition usually resolves upon treatment and resolution of the underlying condition. TSH, thyroxine and T3 are low; in most cases, the TSH level is often within the normal range.
What are expected renin and aldosterone levels in Conns syndrome?
High plasma aldosterone with suppressed renin
What is the mechanism of sitagliptin?
It inhibits DDP-4 (dipeptidyl peptidase-4).
DDP-4 is an enzyme that breakdowns incretins such as GLP-1.
By increasing incretin levels, there is an enhanced insulin release, reduced glucagon secretion and improved blood glucose control
What is pseudohypoparathyroidism?
Rare and genetic condition that occurs when there is a failure of cell response to PTH. PTH is hence elevated but calcium is low and phosphate is raised.
There are also other physical signs shortened metacarpals (especially fourth and fifth), a round face, short stature, calcified basal ganglia, and a low IQ
What is the difference between pseudohypoparathyroidism and pseudopseudohypoparathyroidism?
Pseudohypoparathyroidism will present with raised PTH, low calcium and raised phosphate + other physical features
Pseudopseudohypoparathyroidism has the same physical features as above but a normal biochemistry
What test has replaced the oral glucose tolerance test for acromegaly?
Insulin-like growth factor 1 (IGF-1) measurement
How do the following diabetes drugs work?
SGLT-2 inhibitors
Biguanides
Sulfonylureas
GLP-1 mimetics
DPP-4 inhibitors
SGLT-2 inhibitors (e.g. canagliflozin, dapagliflozin and empagliflozin) - reversibly inhibit sodium-glucose co-transporter 2 (SGLT-2) in the renal proximal convoluted tubule to reduce glucose reabsorption and increase urinary glucose excretion.
Biguanides (e.g. metformin) - decrease gluconeogenesis in the liver and increase insulin sensitivity
Sulfonylureas (e.g. gliclazide) - increase insulin release from beta-cells in the pancreas
GLP-1 mimetics (e.g. exenatide) - mimic incretin which is usually released in the gastrointestinal tract, and has the effect of increasing insulin production
DPP-4 inhibitors (e.g. sitagliptin) - block the action of DPP-4, an enzyme which breaks down incretin
Which diabetes drugs is recommended for patients with CVD and heart failure?
SGLT-2 inhibitors
What is a common cause of impaired hypoglycaemia awareness in T1DM?
Neuropathy of autonomic nervous system
*Certain drugs like beta blockers also blunt awareness.
What is the preferred first-line imaging when presenting with a thyroid nodule?
USS
It can detect lesions as small as 2 mm and provides information on their dimensions, shape, and parenchymal changes. Sonographic criteria are used to classify thyroid nodules, ranging from U1 (benign) to U5 (malignant), which helps to determine the need for further investigations.
If you suspect malignacny, you can then perform other tests such as fine needle aspiration
What is the usual presentation of maturity onset diabetes of the young (MODY)?
They present with persistent, asymptomatic hyperglycaemia without the typical features of T1DM or T2DM
Unlike Type 1 diabetes, patients with MODY usually do not present with diabetic ketoacidosis except under severe stress conditions, and unlike Type 2 diabetes, they are often of normal weight and do not exhibit signs of insulin resistance.
Why is insulin not given in hyperosmolar hyperglycaemic states?
Usually fluid replacement is sufficient to normalise serum glucose and improve patient symptoms.
Giving insulin in hyperosmolar hyperglycaemic state may provoke sudden and dramatic fluid shift between compartments, which may result in central pontine myelinolysis.
What class of diabetes medication has proven cardiovascular benefits?
SGLT-2 inhibitor (e.g. dapagliflozin)
What would the tests results (ACTH and Cortisol) suggest if you performed a high dose dexamethasone suppression test?
- ACTH suppressed, Cortisol not suppressed
- ACTH suppressed, Cortisol suppressed
- ACTH not suppressed, Cortisol not suppressed
- Cushing’s syndrome due to other causes (e.g. adrenal adenomas) *
- Cushing’s disease (i.e. pituitary adenoma –> ACTH secretion)
- Ectopic ACTH secretion
*ACTH is suppressed in high dose dexamethasone test in Cushing’s syndrome because cortisol release is ACTH-independent.
How would you differentiate an adrenal adenoma from bilateral adrenal hyperplasia where both present with Cushing’s syndrome?
Adrenal vein sampling, where you can compare the aldosterone secretion
What are contraindications for prescribing metformin?
Patients at risk of lactic acidosis, including those with:
* diabetic ketoacidosis
* Estimated glomerular filtration rate (eGFR) less than 30 mL/minute/1.73 m2
* Risk of acute kidney injury, such as dehydration, prolonged fasting, severe infection, or shock
* Conditions that may cause tissue hypoxia, such as cardiac or respiratory failure, recent myocardial infarction, or shock
* Hepatic insufficiency, acute alcohol intoxication
What is the initial test to diagnose Cushing’s syndrome?
Low-dose (overnight) dexamethasone suppression test
Patients with Cushing’s syndrome do not have their morning cortisol spike suppressed
*You can also confirm Cushing’s with a 24 hr urinary free cortisol (two measurements are required) or bedtime salivary cortisol (two measurements are required)
What are the different thyroid cancers?
- Papillary (70%) - excellent prognosis
- Follicular (20%)
- Medullary (5%) - Cancer of parafollicular (C) cells, secrete calcitonin, part of MEN-2
- Anaplastic (1%) - Not responsive to treatment, can cause pressure symptoms
- Lymphoma (Rare) - Associated with Hashimoto’s thyroiditis
What is the distribution of diabetic neuropathy?
Sensory loss in a symmetrical ‘glove and stocking’ distribution, with the lower legs affected first
What are some causes of gynaecomastia?
- physiological: normal in puberty
- syndromes with androgen deficiency: Kallman’s, Klinefelter’s
- testicular failure: e.g. mumps
- liver disease
- testicular cancer e.g. seminoma secreting hCG
- ectopic tumour secretion
- hyperthyroidism
- haemodialysis
- drugs: see below
What drugs cause gynaecomastia?
- spironolactone (most common drug cause)
- cimetidine
- digoxin
- cannabis
- finasteride
- GnRH agonists e.g. goserelin, buserelin
- oestrogens, anabolic steroids
What are some side effects of thiazolidinediones (e.g. pioglitazone)?
- weight gain
- liver impairment
- fluid retention - heart failure + peripheral oedema
- bladder cancer
What is the ideal management of Grave’s disease?
- Symptomatic control - propanolol
- Anti-thyroid drugs (e.g. carbimazole, propylthiouracil)
- Radioiodine therapy
How is growth hormone administered and for what conditions?
It is given subcutaneously to:
* proven growth hormone deficiency
* Turner’s syndrome
* Prader-Willi syndrome
* chronic renal insufficiency before puberty