Hormonal Regulation Endocrine

Endocrine Glands

Secrete hormones directly into bloodstream that stimulates action in target tissues

Negative Feedback

Hormone level communicated back to gland (ex: secretion of insulin) → most common type

Positive Feedback

Increasing level of hormone triggers further elevation of hormone (ex: menstrual cycle)

Biological Rhythms

Natural body cycles that control hormone levels → ex: cortisol is low at night and high in morning

What triggers release of hormones when activated?

SNS

Perimenopause

Transitional period, lasts 1-8 years

Menopause

12 months without a period (~50yo) d/t decreased ovarian function l/t low estrogen + progesterone and high FSH + LH (increases risk of breast cancer, osteoporosis, heart disease)

Osteoporosis

Low bone density d/t low intake of nutrients for growth or increase in resorption that occurs with aging

Estrogen (Females)

Inhibits PTH release, slowing osteoclast formation and bone resorption

Parathyroid Hormone (PTH)

Stimulates osteoclast formation/function

Most common disease that affects bone in adults

Osteoporosis

Osteoporosis Risk Factors

Affects 50% of women 50yo+ (post-menopause), asians + caucasians, elderly males, active young athletes, low body fat

T3

Triiodothyronine

T4

Thyroxine

Calcitonin

Thyroid → Osteoblastic

PTH

Parathyroid → Osteoclastic

Osteoblastic

Lowers serum calcium

Osteoclastic

Raises serum calcium

Primary Dysfunction

Occurs in Thyroid

Secondary Dysfunction

Occurs in Pituitary

What is the Thyroid Gland needed for?

Brain development, neurologic function, metabolism

Primary Hyperthyroidism

Graves Disease (most common cause) → autoimmune condition l/t autoantibodies against TSH receptor

Manifestations of Primary Hyperthyroidism

Goiter, forward displacement of eyes, thickening of skin on shins, dysrhythmias, anxiety, weight loss

What does Primary Hyperthyroidism lead to?

Increase in thyroid stimulation l/t increase in T3 + T4 secretion (pituitary attempts to stop with negative feedback by decreasing TSH)

Primary Hyperthyroidism Diagnosis

Decreased TSH + Increased T3 + T4

Secondary Hyperthyroidism Diagnosis

Normal/High TSH + Elevated T3 + T4

Thyroid Storm (Thyrotoxicosis)

D/t extreme levels of thyroid hormone / insufficient treatment of hyperthyroidism + excessive stress + manipulation of gland during thyroid surgery

Thyroid Storm Manifestations

Hyperthermia, tachycardia, HTN, heart failure, agitation, delirium, N, V, D, cardiac collapse, death

Hashimoto’s Thyroiditis (Primary Hypothyroidism)

Destruction of thyroid gland d/t autoimmune dysfunction → autoantibodies directed to thyroglobulin l/t fibrosis

Hashimoto’s Diagnosis

Decreased T3 + T4 + Increased TSH

Secondary Hypothyroidism

Tumors/trauma to pituitary → Increased TRH + Decreased TSH + T3 + T4

Tertiary Hypothyroidism

Tumors/trauma on hypothalamus → Decreased TRH + TSH + T3 + T4

Myxedema Coma

D/t lack of treatment of hypothyroidism, manifestations include HYPOthermia/ventilation/tension/glycemia (hypo-anything)

Catecholamines

Norepinephrine, Epinephrine, Dopamine

Pheochromocytoma

Formation of malignant tumor in adrenal medulla that increases secretion of catecholamines (high vitals)

Adrenal Medulla Releases

Catecholamines

Adrenal Cortex Releases

Aldosterone + Glucocorticoids

Aldosterone

Promotes Water and Na+ resorption and excretion of K+ (RAAS)

Glucocorticoids (aka Cortisol)

Increases blood sugar (gluconeogenesis), suppresses immune system, and promotes anti-inflammatory mechanisms

Primary Adrenocortical Insufficiency

Addison’s Disease → autoimmune disorder affecting adrenal cortex (deficiencies of cortisol + aldosterone)

Addison’s Disease Diagnosis

Increased ACTH + Low Cortisol

Secondary Adrenocortical Insufficiency

Dysfunction of anterior pituitary l/t loss of ACTH d/t chronic glucocorticoid use OR surgery/damage

Secondary Adrenocortical Insufficiency Disorder Diagnosis

Decreased ACTH + Cortisol (d/t insulin induced hypoglycemia)

Manifestations of Secondary Adrenocortical Insufficiency Disorder

Fatigue, weakness, N/V, hypoglycemia, hyponatremia, hyperkalemia

Hyponatremia

Low sodium levels in the bloodstream

Hyperkalemia

High potassium levels

Adrenal Crisis

Acute insufficiency that is life-threatening, precipitated by stressors l/t dehydration, fever, hyperkalemia

Cushing’s Syndrome

D/t excess of cortisol + glucocorticoids (over years): ACTH independent

Cushing’s Syndrome Diagnosis

ACTH Decreased + Cortisol Increased

Cushing Syndrome Causes

Chronic exposure to excess exogenous medications OR endogenous overproduction (too much cortisol)

Cushing’s Disease

D/t pituitary corticotropic adenoma: ACTH dependent (cortisol + ACTH increased)

Primary Hyperaldosteronism

Conn Syndrome → Aldosterone producing adenoma l/t elevated aldosterone and suppressed renin levels

Manifestations of Conn Syndrome

Hypertension, weakness, headaches, polydipsia, polyuria

Secondary Hyperaldosteronism

Renin Dependent → Aldosterone secreted d/t excess secretion of renin (as a response to hypovolemia)

Hypovolemia

Retention of fluid and increase in blood pressure

Renin Dependent Diagnosis

Elevated Aldosterone + Renin

ACTH

Stimulates production of glucocorticoids by Adrenal Cortex

Anterior Pituitary Releases

ACTH, GH, TSH, FSH, LH

Posterior Pituitary Releases

ADH + Oxytocin

Antidiuretic Hormone

L/t conservation of body water by promoting water reabsorption by renal tubules (increased collecting duct permeability)

SIADH Manifestations

Thirst, anorexia, fatigue, decreased NA+, confusion, lethargy

SIADH Diagnosis

Serum hyperosmolality + hyponatremia + urine hyperosmolarity

SIADH

Excess ADH (often from paraneoplastic cancer) or surgery l/t water retention + fluid and volume changes

Central Diabetes Insipidus

Insufficient secretion of ADH, rapid onset; ADH levels low

Nephrogenic Diabetes Insipidus

Inadequate response of renal tubules to ADH (d/t genetics or kidney injury), slow onset, normal or increased ADH

Diabetes Insipidus Diagnosis

Low urine osmolality (unable to concentrate urine), hypernatremia, continued diuresis (water deprivation testing)

Manifestations of Diabetes Insipidus

Polyurina, polydipsia (continuous thirst)