Basics of Endocrinology, Diabetes & Metabolism

Hussam H. AlHawari, MD, FACE, ECNUConsultant Endocrinologist

Assistant Professor of MedicineDepartment of Internal Medicine

Faculty of MedicineUniversity of Jordan

1. Outline the regulation of hormone secretion and the mechanisms of hormone action

2. Explain the function of the hypothalamus, pituitary, adrenal, thyroid, parathyroid, endocrine pancreas, ovary, testis, and their hormones.

3. Discuss some examples of disorders of the endocrine glands named above and their treatment

4. Outline the main principles of laboratory tests and imaging in the diagnosis of endocrine disorders

• The endocrine system consists of endocrine glands that produce and secrete hormones into the blood stream to reach and act on target cells of specific organs.

• These hormones regulate the body's growth, and are involved in cell to cell communication, control metabolic activity, sleep-wake homeostasis, and altered regulation or dysregulation of adaptive response in various physiologic and pathophysiologic states.

• The hormones are released into the bloodstream and may affect one or several organs throughout the body.

• The endocrine system is regulated by feedback in much the same way that a thermostat regulates the temperature in a room.

• Thyroid gland• It helps regulate the body’s metabolism (how

the body gets energy from food) and blood-calcium levels by secreting three hormones:

– Calcitonin: Regulates blood calcium levels by slowing down the amount of calcium lost from bones

– Thyroxine: Stimulates your body to use more oxygen and increases metabolism

– Triiodothyronine: Affects metabolism, growth and development, body temperature, and heart rate

• Screening for thyroid disease? TSH +- T4 and T3 based on clinical picture

Thyroid imaging? 1. Thyroid ultrasound (anatomy )

Thyroid uptake and scan (physiology/pathology )

• Parathyroid glands• Near the thyroid are 4

tiny pea-shaped organs, the parathyroids, that secrete parathormone to control and balance the levels of calcium and phosphate in the blood and tissue fluids.

Physiology and Pathology

• The pineal gland is a pea-sized gland that apparently responds to exposure to light and regulates activity levels over the course of the day.

• It produces melatonin, a serotonin derived hormone, which affects the modulation of sleep patterns in both seasonal and circadian rhythms.

• The pancreas lies in the curve of the duodenum and controls the level of sugar in the blood by secreting insulin and glucagon.

• The hypothalamus: The hypothalamus is a part of the brain located near the pituitary gland. It assists the pituitary gland in regulating other glands by releasing hormones that communicate with it

– Corticotropin-releasing hormone: Tells the pituitary gland to secrete adrenocorticotropic hormone

– Dopamine: Tells the pituitary gland to produce less prolactin

– Gonadotropin-releasing hormone: Tells the pituitary to secrete follicle-stimulating hormone and luteinizing hormone

– Growth-hormone-releasing hormone: Tells the pituitary gland to secrete growth hormone

– Somatostatin: Tells the pituitary gland to release less growth hormone and thyroid-stimulating hormone

– Thyrotropin-releasing hormone: Tells the pituitary gland to release thyroid-stimulating hormone and prolactin

• The pituitary gland produces the largest number of different hormones and, therefore, has the widest range of effects on the body's functions.

– Adrenocorticotropic hormone: Stimulates the suprarenal glands to produce cortisol, which is a stress hormone (meaning production of this hormone is triggered by stressful situations)

– Antidiuretic hormone: Regulates fluid balance in the body– Follicle-stimulating hormone: Stimulates the ovaries to produce eggs,

or ova, in women and sperm production in men– Growth hormone: Stimulates growth during childhood and helps to

maintain bone and muscle mass in adults– Luteinizing hormone: Helps regulate testosterone in males and estrogen

in women– Melanocyte-stimulating hormone: Stimulates the production of

melanin (skin pigment) by the melanocytes in the skin and hair– Oxytocin: Stimulates lactation (milk production) in the breasts and

contraction of the smooth muscles of the uterus during birth– Prolactin: Stimulates milk production after the birth of a baby– Thyroid-stimulating hormone: Stimulates the thyroid gland to produce

the thyroid hormones that regulate metabolism and blood calcium levels

• The suprarenals: The suprarenal glands sit atop the kidneys. They respond to stress, affect fluid balance in the body, and make a small amount of sex hormones:

– Aldosterone: Decreases sodium loss in the blood to regulate blood volume and blood pressure

– Cortisol: Helps regulate the body’s use of proteins, fats, and carbohydrates and helps regulate blood pressure and heart function

– Epinephrine (adrenaline): Increases heart rate, increases blood flow to the brain and muscles, and takes glucose out of storage for use as fuel

– Norepinephrine (noradrenaline): Constricts blood vessels and increases blood pressure; also takes glucose out of storage to fuel the muscles and brain

– Sex hormones: Involved with the development of sex organs at the beginning of puberty

• Gonads• These reproductive

glands—the testes in males and the ovaries in females, and, to a lesser extent, the suprarenal (adrenal) glands —secrete androgens (including testosterone) and estrogens.

1. Along with the nervous system, the ______ system coordinates the various activities of body parts. A) digestive B) endocrine C) circulatory D) respiratory E) excretory

A) digestive B) endocrine C) circulatory D) respiratory E) excretory

2. The pituitary is located beneath the thalamus in the brain. A) True B) False

A) True B) False

3. The hypothalamus regulates ___________. A) heart rate B) body temperature C) water balance D) glandular secretions E) all of the above

A) heart rate B) body temperature C) water balance D) glandular secretions E) all of the above

4. The posterior pituitary stores and secretes _________. A) ADH and oxytocin B) growth hormone and gonadotropin- releasing hormone C) estrogen and testosterone D) aldosterone and cortisone E) adrenalin and insulin

A) ADH and oxytocin B) growth hormone and gonadotropin-releasing hormone C) estrogen and testosterone D) aldosterone and cortisone E) adrenalin and insulin

5. Hypothalamic releasing and release-inhibiting hormones are transported from the hypothalamus to the anterior pituitary by way of __________. A) the general bloodstream B) a portal system of blood vessels directly connecting the two organs C) direct contact between the two organs D) a cascade of release-inhibit-release-etc. interactions

A) the general bloodstream B) a portal system of blood vessels directly connecting the two organs C) direct contact between the two organs D) a cascade of release-inhibit-release-etc. interactions

6. Hormones produced by the anterior pituitary that have a direct effect on the body, rather than trigger another gland, are __________. A) GH, prolactin, and MSH B) TSH, ACTH, and gonadotropic hormones C) testosterone and estrogen D) FH, LSH and progesterone

A) GH, prolactin, and MSH B) TSH, ACTH, and gonadotropic hormones C) testosterone and estrogen D) FH, LSH and progesterone

7. If the production of GH increases in an adult after full height has been attained, only certain bones respond and result in acromegaly. A) True B) False

A) True B) False

8. The parathyroid glands are located __________ . A) below the thyroid, hence the name "para" B) above the thyroid, hence the name "para" C) imbedded in the posterior surface of the thyroid gland D) distant from the thyroid but named because there are two and they resemble the thyroid glands

A) below the thyroid, hence the name "para" B) above the thyroid, hence the name "para" C) imbedded in the posterior surface of the thyroid gland D) distant from the thyroid but named because there are two and they resemble the thyroid glands

9. If ______ is lacking in the diet, the thyroid gland enlarges, producing a goiter. A) thyroxin B) iron C) iodine D) calcium E) phosphorus

A) thyroxin B) iron C) iodine D) calcium E) phosphorus

10. If the thyroid fails to develop properly from childhood, a condition called ______ results. A) goiter B) cretinism C) acromegaly D) pituitary dwarfism E) myxedema

A) goiter B) cretinism C) acromegaly D) pituitary dwarfism E) myxedema

11. In addition to thyroxine and triiodothyronine, the thyroid gland produces ________. A) TSH B) ACTH C) calcitonin D) FSH E) gonadotropin-releasing hormone

A) TSH B) ACTH C) calcitonin D) FSH E) gonadotropin-releasing hormone

12. In __________ diabetes the pancreas is NOT producing insulin. A) type I B) type II C) Gestational D) all of the above

A) type I B) type II C) Gestational D) all of the above

13. Type II diabetes usually occurs in people who are obese and inactive. A) True B) False

A) True B) False

14. Glucagon increases the action of insulin. A) True B) False

A) True B) False

15. The adrenal glands consist of _________. A) the inner and outer layer of the kidney B) the inner medulla and the outer cortex C) lower adrenal and upper paradrenal sections D) ACTH and BCTH sections

A) the inner and outer layer of the kidney B) the inner medulla and the outer cortex C) lower adrenal and upper paradrenal sections D) ACTH and BCTH sections

16. Parathyroid hormone (PTH) ___________. A) stops the absorption of calcium from the intestine B) stimulates the release of calcium by the kidneys C) causes blood calcium level to decrease D) causes blood phosphate level to decrease E) all of the above

A) stops the absorption of calcium from the intestine B) stimulates the release of calcium by the kidneys C) causes blood calcium level to decrease D) causes blood phosphate level to decrease E) all of the above

17. Anabolic steroids are ______ forms of testosterone. A) natural B) synthetic C) super-active D) ineffective

A) natural B) synthetic C) super-active D) ineffective

18. The _________ produces the hormone melatonin. A) pituitary gland B) pineal gland C) thyroid gland D) pancreatic gland E) hypothalamus

A) pituitary gland B) pineal gland C) thyroid gland D) pancreatic gland E) hypothalamus

19. The pancreas has both exocrine and endocrine tissue. A) True B) False

A) True B) False

20. The primary target organ of aldosterone is _________. A) the liver B) the pancreas C) the kidney D) all of the above

A) the liver B) the pancreas C) the kidney D) all of the above