Endocrinology Flashcards
What effect does biotin have on thyroid function?
Can cause spurious results on TFTs, as it interferes with assay.
Can cause false positive Graves-like appearance
Patients taking biotin should hold the supplement for two days prior to assessing thyroid function and longer if they are taking more than 10 mg a day.
What are the main associations with MEN2 syndrome?
WHat is the main difference between MEN2A and MEN2B?
MEN2A = medullary thyroid cancer, pheochromocytoma, and primary parathyroid hyperplasia
MEN2B = MTC + pheochromocytoma but not hyperparathyroidism
What are the main associations with MEN1 syndrome?
3Ps
Tumours of
- parathyroid glands
- anterior pituitary
- enteropancreatic endocrine cells
2011B40
A 52 year old male presents with flushing, watery diarrhoea and wheezing. Urinary 5HIAA is 120mg/dL (2-8). A CT of the abdomen shows multiple liver metastases.
What is the site of primary tumour? A. colon B. oesophagus C. rectum D. small intestine E. stomach
Small intestine
Distribution frequency =
GIT – 55%
- Small intestine – 45%, most commonly in the ileum
- Rectum 20%, Appendix 16%, Colon 11%, Stomach 7%
Bronchopulmonary system – 30%
What is the most common clinical presentation of carcinoid syndrome?
Chronic flushing (85%) & diarrhea (80%)
Result of serotonin (and other vasoactive substances) secretion into the systemic circulation
What test has >90% sensitivity and specificity for carcinoid syndrome diagnosis?
24-hour urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA)
- Values >100 md/day indicative of carcinoid syndrome (normal 2-8mg/day)
5-HIAA is an end product of serotonin metabolism
5-HIAA is most useful in patients with primary midgut (jujunoileal, appendiceal, ascending colon) carcinoid tumours, which produce the highest levels of serotonin
What the effect of SGLT2 inhibitors on glucagon and insulin levels?
It decrease glucose levels, which leads to reduction in insulin and increase in glucagon
What is the main orexigenic hormone from the stomach that promotes hunger?
Ghrelin
What are the main hunger-promoting hormones from the arcuate nucleus of the hypothalamus?
Agouti-related peptide (AgRP) Neuropeptide Y (NPY)
Where is leptin secreted from?
What are its main effects?
Secreted by adipocytes
Acts as the body’s marker of fat stores
An increase will stimulate melanocortin, which suppresses appetite
What is the main difference between Roux-en-Y and Sleeve gastrectomy in terms of weight loss mechanism?
Both are restrictive, but Roux-en-Y is also malabsorptive
What is the most effective treatment for morbid obesity?
Bariatric surgery
What is the proven most effective T2DM prevention strategy?
Intensive lifestyle program with diet and exercise
What are the effects of insulin on glucose utilisation, proteins and fats?
Glucose utilisation
- Stimulates uptake of glucose by skeletal muscle and fat
- Inhibits hepatic gluconeogenesis by decreasing free fatty acids to liver -> decreased gluconeogenesis
Fat
- Promotes storage of triglycerides in adipose tissue
- Inhibits lipolysis of stored triglycerides from adipose tissue
Protein
- Increases protein synthesis
What are incretins?
What is their function?
They are insulin secretagogues.
- Amplification effect -> determines up to 70% of post-prandial insulin production
- After meal, GLP1 / GIP peptide hormones bind to pancreas -> production of insulin
- DPP4 cleaves GLP1, rendering it inactive
- Incretin effect is impaired in DM
Which transporter in the kidney is responsible for up to 90% of PCT reabsorption of glucose?
SGLT2 - Sodium glucose co-transporter 2
Which hypoglycaemic agents promote weight loss?
Metformin
GLP-1 agonists
SGLT2 inhibitors
Which hypoglycaemic agent can improve BP?
SGLT2 inhibitors via weak diuretic affect
Which hypoglycaemic agents have shown to reduce CV death?
Empagliflozin
Liraglutide
What are the main auto-abs in T1DM? (4)
GAD
IA2
Insulin
ZnT8
What is the duration of action of Ryzodeg 70/30?
42 hours
What are 4 key advantages of insulin pumps over injections?
Reduced HbA1c
Reduced severe hypos
Improved QoL
May decrease mortality (CV and overall)
What is the role of RANK Ligand in bone?
Cytokine which is essential for development and survival of osteoclasts -> promotes bone resorption
Is bone mineral density a more sensitive or specific marker of fracture risk?
Specific
Low sensitivity
At what BMD range do most fractures occur?
Osteopenic range -> -1 -> -2.5
What is the biggest risk factor for fracture in osteoporosis?
Previous fracture
Which type of bone is most affected in steroid-induced OP?
Trabecular (cancellous)
What is the PBS criteria for bone health treatment in long-term steroid use?
> 7.5mg/day of prednisolone for over 3 months + T-score <1.5
What are the three ways in which PTH acts to increase serum calcium?
- Promotes formation of calcitriol in kidneys, which increases GIT absorption of Ca and Phos
- Mobilises calcium from bone by promoting resorption
- Increases renal calcium reabsorption
What is the best way to distinguish between factitious hypoglycaemia and insulinoma?
C-peptide level
- will be high in insulinoma
What diagnosis is consistent with diffusely increased uptake on Thyroid Uptake Scan?
Graves Disease
What are the indications for treating subclinical hypothyroidism? (3 definitive)
Treat if ->
- TSH >10 - Symptomatic - Pregnant (TSH >4)
Consider if:
- Age <65 - Heart failure - TPO / Tg ab positive - Dyslipidaemia