Endocrine Flashcards
What is the mechanism of action of Propylthiouracil?
inhibits the production of new thyroid hormone in the thyroid gland by inhibiting the enzyme thyroid peroxidase, which usually converts iodide to an iodine molecule and incorporates the iodine molecule into amino acid tyrosine.
Which version of MODY is most sensitive to sulphonylureas:
MODY 1
MODY 2
MODY 3
HNF1A mutations (MODY3) is the group that are sensitive to sulphonylureas
What marker is used for each of the following thyroid cancers as post treatment tumour marker:
Follicular?
Papillary?
Medullary?
Follicular - Anti-TG
Papillary - Anti-TG
Medullary - Calcitonin
Familial Hypocalciuric hypercalcemia (FHH):
Is it benign or malignant?
Autosomal dominant or recessive?
What specific mutation?
benign cause of hypercalcemia
autosomal dominant
results from an Inactivating mutation in the Calcium sensing receptor(CaSR) makes the parathyroid gland less sensitive to calcium.
this means that a higher than normal serum calcium concentration is required to reduce PTH release (set point raised)
What is the most specific test for Graves disease?
TSH receptor antibodies
Mechanism of action of cinacalcet?
directly lowers parathyroid hormone levels by increasing the sensitivity of the calcium sensing receptors to activation by extracellular calcium, resulting in the inhibition of PTH secretion.
How does autosomal dominant hypocalcaemia act on the calcium sensing receptor?
Is this disease symptomatic?
What is the biggest risk with treatment? Why?
Lowers the set point for calcium feedback, so lower than normal calcium levels are sensed as normal
Usually not symptomatic
Treated with calcium and vitamin D can lead to increase urinary secretion of calcium causing risk of urolithiasis
How is MEN1 inherited?
What about MEN2?
What gene is mutated in MEN2?
MEN1 gene mutation = autosomal dominant
MEN2 mutation = autosomal dominant
Mutation = RET proto-oncogene.
What are the 3 P’s of MEN1 disease?
Which one is most common?
Parathyroid Tumours = most common
- These typically lead to primary hyperparathyroidism, causing hypercalcemia and related complications such as kidney stones, bone pain, and osteoporosis.
Pancreatic Neuroendocrine Tumours:
- These can be functional (producing hormones like insulin, gastrin, glucagon, etc.) or non-functional.
Pituitary Tumours:
- Commonly prolactinomas or growth hormone-secreting tumors
How does MEN2A differ from MEN2B?
MEN2A:
– Medullary Thyroid Carcinoma (MTC): Nearly all patients develop MTC, a cancer originating from the parafollicular C cells of the thyroid, which can produce calcitonin.
– Pheochromocytoma: Tumors of the adrenal medulla causing excessive production of catecholamines, leading to hypertension, palpitations, and other symptoms.
– Parathyroid Hyperplasia or Adenomas: Leading to hyperparathyroidism.
MEN2B:
– Characterized by MTC and pheochromocytoma, similar to MEN2A.
– Distinguished by the ABSCENCE of parathyroid involvement.
– Patients often exhibit a marfanoid habitus (tall, slender build with long limbs) and mucosal neuromas (benign nerve tissue growths).
Which of the following gene mutation is the most common cause of monogenic diabetes?
IPF-1
Glucokinase
HNF-1b
HNF-4 alpha
HNF-1 alpha
HFN-1 Alpha
Which of the following type of monogenic diabetes is most sensitive to sulphonylurea?
IPF-1
NHF-4 alpha
HNF-1 beta
Glucokinase
HNF-1 alpha
HFN-1 Alpha
What is the mechanism of action of Sulfonureas?
Drug example
Sulphonylureas work by binding to and closing ATP-sensitive potassium (KATP) channels on the beta cells, leading to depolarization and insulin release.
example = gliclazide
The above thyroid technetium scintiscan is unlikely to be seen in:
And why?
Graves disease
Subacute thyroiditis
Amiodarone therapy
Thyroxine therapy
Postpartum thyroiditis
Graves disease
MOA = the thyroid gland takes up an excessive amount of radioactive technetium when compared to normal thyroid tissue. This increased uptake is a result of the autoimmune antibodies known as thyroid-stimulating hormones (TSH receptor antibodies) present in Graves’ disease. These antibodies overstimulate the thyroid gland, leading to increased production of thyroid hormones.
Thyroiditis = “dumps” thyroid
Mechanism of action of Carbimazole?
TPO substrate.
inhibits the organification of iodide and coupling of iodothyronine residues leading to the suppression of thyroid hormone synthesis.
What is the action of dopamine on the pituitary hormones?
Dopamine acts as an inhibitor of prolactin secretion
What is most important reason for measuring thyroid stimulating antibodies in the third trimester of pregnancy in a woman with Graves disease?
Allow withdrawal of anti-thyroid medication
Detect foetal goitre
Predict risk of flare of thyrotoxicosis post-partum.
Predict risk of neonatal thyrotoxicosis
Guide dose adjustment of anti-thyroid medication.
Predict risk of neonatal thyrotoxicosis
Hormones of the anterior pituitary = mnemonic FLAGTOP.
F for FSH
L for LH
A for ACTH
G for Growth Hormone
T for TSH
O for MelanOcyte stimulating hormone
P for Prolactin
How do you diagnosis Hashimoto’s?
Treatment?
TPO antibodies with high TSH and low T4
Treat with Levothyroxine
What is the role of osteoprotegrin in bone resorption?
osteoPROTEGrin PROTECTs
OPG inhibits bone resorption and binds with strong affinity to its ligand RANKL, thereby preventing RANKL from binding to its receptor RANK
‘Decoy’ receptor
Which of the following affect the DIPs and which affect the PIPs?
Psoriasis
OP
Gout
SLE
RA
PIP = SLE + RA
DIP = OA, Gout, Psoriasis (often both)
For hyperthyroidism in pregnancy, what drug is used in the first trimester?
What about the second and third trimesters?
1st trimester = Propylthiouracil
2nd & 3rd = Carbimazole
Hyperthyroidism in pregnancy, if left untreated, can lead to maternal and fetal complications such as preterm birth, low birth weight, and preeclampsia.
What is the main reason for the deterioration in glycemic control over time as seen in patients with type 2 diabetes mellitus?
Why?
medication non-compliance
decreasing insulin secretion
reduced energy expenditure
increasing insulin resistance
increasing obesity
Incorrect
decreasing insulin secretion
Initially, the body compensates for insulin resistance by increasing insulin production, but over time, pancreatic β-cells fail to maintain this compensatory mechanism.
This β-cell dysfunction leads to a progressive decline in insulin secretion, exacerbating hyperglycemia.
Which of the following decreases the level of Adiponectin?
Obesity
Exercise
Bariatric surgery
Thiazolidinediones therapy
Calorie restricted diet
obesity
Adiponectin levels are inversely related to body fat.
In obesity, there is a decrease in adiponectin levels, which is associated with increased insulin resistance and cardiovascular risk.
Adiponectin is known for its anti-inflammatory and insulin-sensitizing properties.
Hence, lower levels in obesity contribute to the pro-inflammatory state and insulin resistance characteristic of this condition
