Endocrinology Bullet Points For NEET-PG & INICET
1. The pancreas has both endocrine and exocrine functions. The endocrine pancreas regulates glucose metabolism, while the exocrine pancreas facilitates the chemical digestion of food.
2. In men, increased sex hormone binding globulin (SHBG)
→ decreased free testosterone
→ increased risk of unopposed estrogen activity → gynecomastia.
In women, decreased SHBG
→ increased free testosterone
3. Janus kinase (JAK) inhibitors, approved for a variety of autoimmune diseases, can exert anti-inflammatory effects by preventing signal propagation of a number of cytokines.
4. Empty sella syndrome (ESS):
In primary ESS, increased pressure in the sella turcica flattens the pituitary along the walls of the cavity.
Secondary ESS is the regression of the pituitary secondary to injury or radiation.
Both give the impression of an empty sella on imaging. This syndrome occasionally results in endocrine dysfunction.
5. Damage to the pituitary stalk can lead to decreased secretion of pituitary hormones secondary to disruption
of the hypophyseal portal system (anterior pituitary) and hypothalamic neurons (posterior pituitary). The exception is prolactin (PRL) secretion, which is increased due to this same disruption, as dopamine from the hypothalamus usually inhibits PRL secretion.
can you answer it?
On examination of a pituitary adenoma biopsy, a pathologist observes extensive intracellular acidophilic granules. What hormone(s) might this adenoma be secreting?
6. Secondary and tertiary adrenal insufficiency (caused by pituitary or hypothalamic damage, respectively)
cause cortisol deficiency but do not cause hyperpigmentation (decreased ACTH and thus decreased MSH).
Because aldosterone secretion is primarily regulated by the renin- angiotensin-aldosterone system
(RAAS), these patients with adrenal insufficiency do not typically have hypovolemia, hypotension,m hyponatremia, or hyperkalemia.
7. Compression of the optic chiasm by a pituitary tumor causes bitemporal hemianopia, a specific visual field
defect defined by loss of the left temporal field in the left eye and the right temporal field in the right eye.
8. GH excess in children causes gigantism, whereas GH excess in adults causes acromegaly.
9. Ischemic necrosis of the pituitary (Sheehan syndrome): Postpartum hemorrhage causing hypovolemic
shock results in ischemic necrosis of the pituitary. This is due to the increase in size and blood demand of the pituitary during pregnancy.
10. Central DI is due to a lack of ADH. Nephrogenic DI is due to a failure to respond to ADH.
11. SIADH = Sodium Is Always Decreased Here
12. Hyponatremia must not be corrected too quickly because this can result in central pontine myelinolysis. This potentially fatal disease is caused by damage to the myelin sheaths of nerves in the brain stem from rapid changes in osmolality. Patients can experience altered mental status, acute paralysis, and dysphagia, among other neurologic symptoms.
13. A goiter is an enlarged thyroid gland due to any cause, such as inflammation, tumor, or autoimmune disease. Endemic goiter, caused by iodine deficiency, is the most common cause of goiter worldwide.
14. A thyroglossal duct cyst develops when the thyroglossal duct does not close, persisting in the midline near
the hyoid bone or at the base of the tongue .Ectopic thyroid tissue is most commonly found at the base of the tongue.
15. Propylthiouracil (PTU) and methimazole, used to treat hyperthyroidism, inhibit thyroid peroxidase. PTU also inhibits 5′-deiodinase, which converts T4 to active T 3
16. T4 is the major hormone produced by the thyroid, but it needs to be activated by 5′-deiodinase in the periphery to T3
17. Changes in TBG levels can alter the total levels of T3 and T4 but will not change free, active T 3 and T4 levels. Thus, patients are euthyroid and do not show signs of hypo- or hyperthyroidism.
18. The Wolff-Chaikoff effect is a protective downregulation of thyroid hormone production in the presence
of large amounts of iodine (seen with cardiac catheterization and CT with contrast).
In contrast, the Jod-Basedow effect is the overproduction of thyroid hormone, causing overt hyperthyroidism in the presence of large amounts of iodine in persons who fail to manifest the Wolff- Chaikoff effect.
19. Thyroid storm is a life-threatening form of thyrotoxicosis characterized by high fever, tachyarrhythmia,
psychosis, confusion, diarrhea, and liver dysfunction. It is managed with intensive care unit-level support, antithyroid medications, glucocorticoids, and β-adrenergic blockers.
20. In newborns, hypothyroidism causes cretinism (mental retardation, short stature, coarse features, umbilical hernia). Thyroid hormone deficiency during fetal development may be due to a failure of thyroid gland formation, inability to synthesize hormone (T3/T4), lack of iodine, radioiodine taken by themother, or untreated hypothyroidism in the mother.
21. Most signs and symptoms of hyperthyroidism derive from increased BMR and sympathetic tone.
Conversely, most signs and symptoms of hypothyroidism derive from decreased BMR and sympathetic tone.
22. Follicular carcinoma spreads hematogenously.
23. MEN 1 arises from mutations in the self- named men1 oncogene, whereas MEN 2A and 2B stem from mutations in the ret oncogene.
24. DiGeorge syndrome is a consequence of abnormal development of branchial pouches 3 and 4 due to chromosome 22q11.2 deletion. Clinical manifestations include hypocalcemia secondary to absence of the parathyroid glands, immune deficiency secondary to absence of thymic tissue leading to abnormal T-cell maturation, and congenital cardiac malformations.
25. Branchial cysts are lesions found lateral to the midline of the neck. They result from failed obliteration
of the temporary cervical sinuses.
In contrast, thyroglossal duct cysts, found medially, result from failed obliteration of the thyroglossal duct as the thyroid gland migrates inferiorly during development.
26. The inferior parathyroids are derived from the third branchial pouch, whereas the superior parathyroids are derived from the fourth branchial pouch, an apparent reversal of the rostrocaudal arrangement of these structures during development. This is due to the paired migration of the inferior parathyroids with the thymus, which facilitates enhanced caudal migration.
27. Vitamin D deficiency in children causes rickets, which is characterized by the inability to calcify newly formed bone matrix (osteoid) with consequent malformation (bowing) of long bone.
28. Vitamin D deficiency in adults results in osteomalacia. Like rickets, this condition is characterized by defective mineralization of bone. Osteomalacia causes pain, proximal muscle weakness, and bony deformities. It is treated with vitamin D replacement.
29. Calcitonin levels are high in medullary thyroid cancer, since parafollicular C-cells proliferate. Calcitonin can deposit as amyloid within the tumor.
30. Causes for hypercalcemia—
Intoxication with vitamin D
Alkali (milk-alkali syndrome)