Endocrine2 Flashcards
If you suspect primary adrenal insufficiency, what tests would you perform to confirm or deny this diagnosis?
Initial evaluation = 8am serum cortisol and plasma ACTH. Low cortisol with high ACTH confirms PAI, low cortisol with low ACTH suggests central (pituitary or hypothalamic) adrenal insufficiency.
ACTH stimulation test is performed next. Infusion of cosyntropin generally»_space; rapid increase in serum cortisol but this won’t happen in PAI.
What therapy would you offer to a patient with macroprolactinoma (>10mm) / symptomatic tumor of the pituitary?
Patients with macroprolactinoma or symptomatic tumor of any size should be treated with dopamine agonists (cabergoline, bromocriptine) which can normalize prolactin levels and decrease tumor size. If no response from cabergoline»_space; transphenoidal resection.
Note: ^ prolactin levels suppress gnRH, LH, and estradiol»_space; oligo-amenorrhea in premenopausal females.
What antibody marker is elevated in Hashimoto’s disease?
Hashimoto’s thyroiditis = chronic lymphocytic thyroiditis, subclinical hypothyroidism with normal thyroxine and slightly elevated levels of TSH and symmetrically enlarged nontender thyroid.
Elevated antithyroid peroxidase (anti-TPO) or antithyroglobulin antibodies are present in most cases.
Rx with levothyroxine is recommended in Pt with subclinical hypothyroidism with elevated TPO even if they’re asymptomatic.
Which antibody marker is elevated in Grave’s disease?
Thyroid stimulating immunoglobulin. TSIs stimulated TSH receptors on thyroid follicular cells»_space; thyroid hormone overproduction rather than hypothyroidism.
Why does G6PD cause hemolysis?
G6PD is responsible for catalyzing the reduction of NADP to NADPH, the first step in the HMP shunt. This is the only source of NADPH in RBC. NADPH is needed to form reduced glutathione which protects RBC from oxidative injury. In the absence of G6PD and presence of oxidizing agents, Hb becomes denatured to methemeglobin, denatured globin, and sulfhemoglobin. Causes formation of insoluble masses (Heinz bodies) that attach to RBC membrane»_space; decreased membrane pliability and promote hemolysis and removal from splenic macrophages.
At what point would you switch from an IV insulin infusion to a SubQ insulin in the treatment of DKA?
Initially treat with IV continuous insulin infusion. Transition to SQ insulin during if the following: able to eat, glucose < 200 mg/dL, anion gap < 12, and serum HCO3 > 15. Should try to overlap SC and IV insulin by 1-2 hrs.
** Note: you want to use regular insulin when dosing for DKA for rapid dose titration.
What are the major side effects associated with PTU use?
PTU can cause severe liver injury and acute liver failure. But, PTU is still used during first trimester of pregnancy due to fetal teratogenicity with Methimazole.
What are the major side effects associated with methimazole use?
Agranulocytosis. Presents as sore throat, severe fever, and leukopenia.
Why do you get tachycardia with thyrotoxicosis?
Thyrotoxicosis causes increased sensitivity to catecholamines due to increased expression of B1 AR.
What are the screening guidelines for Diabetes?
Screening for diabetes is recommended in Pt with sustained BP > 135/80 and may be considered in ALL Pt > 45 yo as well as at any age if Pt has additional risk factors for DM. Screening options include fasting plasma glucose, 2 hr oral glucose tolerance test and HbA1c.
Calcitonin is a marker for medullary thyroid cancer which arises from ___ of the thyroid gland whereas papillary and follicular cancers arise from ___ of the thyroid gland:
parafollicular C cells in medullary thyroid cancer.
thyroid epithelial cells in papillary/follicular cancers.
Why are thyroid hormone levels increased during pregnancy?
Estrogen increases the level of T4 binding globulin. This effect is seen in pregnancy or in Pt taking OCP or estrogen supplements because estrogen prevents its catabolism and actually promotes its synthesis in the liver. Total thyroid hormone levels are elevated but Pt with normal hypothyroid pituitary thyroid function maintain a euthyroid state and normal TSH level because thyroid hormone production increases to match the increased TBG production.
How do treatment outcomes differ in using radioiodine ablation therapy in Graves vs toxic multinodular goiter?
In Graves, the diffuse uptake»_space; permanent hypothyroidism within months in about 90% of cases.
When RAI is used to treat toxic multinodular goiter then the radioisotope is taken up only by autonomous thyroid tissue.
