Week 3 Flashcards
Following insulin binding at the insulin binding site of the insulin receptor, what happens to levels of glycogen synthase?
Glycogen synthase levels will increase in response to insulin receptor activation leading to tyrosine phosphorylation of the PI3K-AKT pathway.
Which category of diabetic drugs has an overall drug interaction effect of decreasing the peak plasma concentration of many orally administered drugs?
Drugs that target glucose absorption i.e. α-glucosidase inhibitors, bile binding resins (not as much amylin analogs) are likely to interfere with the uptake of other oral drugs as they interfere with absorption.
How do calcimimetics affect levels of parathyroid hormone and what is the mechanism underlying this effect?
Calcimimetics “mimic” calcium by binding the calcium-sensing receptor, which then makes it appear as if there are greater levels of serum calcium than there actually are. Thus, parathyroid hormone levels should decrease.
A 60-year-old woman with a history of type 2 diabetes mellitus presents with pruritus, diffuse bone pain, proximal muscle weakness, and frequent urination. Laboratory studies show a serum calcium 11.8 mg/dL, a serum phosphate level of 6.0 mg/dL and a serum creatinine level of 2.7 mg/dL. What metabolite is most likely to be elevated in this patient?
This patient likely has elevated levels of vitamin D and calcitriol leading to hypercalcemia and hyperphosphatemia. Most of the clinical findings are due to these elevated labs, and progression can lead to bone and kidney problems due to calcium stones. In this patient, the kidney problems could very well also be due to progression of her diabetes.
What are the similarities and differences in lab findings in patients with familial hypocalciuric hypercalcemia versus primary hyperparathyroidism?
These two conditions similarly exhibit elevated calcium and parathyroid hormone, but 24 hour urinary calcium is low in FHH due to a mutation of calcium sensing receptor in the kidney which has a lower set point for reabsorption of the filtrated calcium, therefore calcium gets reabsorbed at a higher rate. In PHPTH 24 hour urinary calcium can be normal or elevated due to mobilization of calcium from the bones by elevated PTH.
Which secondary growth abnormality is the least likely to be treatable with exogenous growth hormone?
IGF deficiency, especially if caused by abnormalities or defects in the GH receptor, is highly unlikely to respond to increased levels of GH.
If fetal insulin were to mimic adult insulin, how might this affect the risk of macrosomia in a woman with gestational diabetes and why?
If hypothetically fetal insulin were to mimic adult insulin, the risk of macrosomia would decrease as adult insulin would not be able to stimulate the IGF1 receptor with as much potency as fetal insulin.
A five year old girl presents with breasts T3, low levels of T3 and T4, and high TSH levels. Gonadotropin levels are likely to be pre-pubertal, pubertal, or high?
Pre-pubertal. This patient has peripheral precocious puberty secondary to primary hypothyroidism.
A 19 year old female presents with normosmia, breasts T2, PH T1, and no history of vaginal bleeding. Defects in what neuronal signaling pathway are likely to be present in this patient?
Normosmia and signs of GnRH deficiency with normosmia are most likely to be associated with defects in the KISS1 or neurokinin B signaling axes (in contrast with Kallmann syndrome)
What are the effects of thyroid hormone on growth that are independent of the effects of growth hormone?
Thyroid hormone stimulates proliferation of chondrocytes and epiphyseal fusion.
