PATHO: Hormonal Regulation

Hormonal Regulation

Physiologic mechanisms that regulate secretion and action of hormones to support metabolism, perception, interception, and responses to internal/external stimuli.

Interception

Stopping a process that is already in progress.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream to act on target tissues.

Negative Feedback Loop

A regulatory mechanism where an increase in a substance causes inhibition of further secretion (ex: insulin secretion decreases when glucose drops).

Positive Feedback Loop

A regulatory mechanism where a hormone stimulates further hormone release (ex: LH stimulating estradiol which increases LH).

Biological Rhythm Hormone Secretion

Hormone release based on circadian patterns (ex: cortisol highest in morning, lowest at night).

CNS Hormone Stimulation

Hormone release triggered by stress or neurologic signals (ex: cortisol during stress).

Five Functions of Hormones

Reproductive/CNS differentiation, growth and development, secondary sex characteristics, metabolism, adaptive stress responses.

Menopause

Permanent cessation of menstruation for 12 consecutive months, usually around age 50.

Perimenopause

Transitional period before menopause (1–8 years) with fluctuating hormone levels.

Estrogen Protective Effects

Protects bone, cardiovascular system, and other tissues.

Osteoporosis

Low bone density due to increased bone resorption or decreased bone formation.

Osteoblasts

Cells that build bone.

Osteoclasts

Cells that break down bone and release calcium into bloodstream.

Osteocytes

Bone cells that maintain bone homeostasis.

Parathyroid Hormone (PTH)

Hormone that stimulates osteoclast activity and increases serum calcium.

DEXA Scan

Test used to diagnose osteoporosis by measuring bone density.

Thyroid Hormones

T3 and T4 regulate metabolism, brain development, and neurologic function.

Calcitonin

Thyroid hormone that lowers serum calcium by stimulating osteoblast activity.

Parathyroid Gland

Gland that raises serum calcium by stimulating osteoclast activity.

Hypothalamic-Pituitary-Thyroid Axis

TRH → TSH → T3/T4 hormonal pathway.

Primary Hyperthyroidism

Excess thyroid hormone due to thyroid gland dysfunction.

Graves Disease

Autoimmune disorder causing excess thyroid hormone production.

Secondary Hyperthyroidism

Excess thyroid hormone due to excess TSH from pituitary tumor.

Thyroid Storm

Life-threatening hyperthyroid crisis with extreme tachycardia, hyperthermia, and hypertension.

Primary Hypothyroidism

Low thyroid hormone due to thyroid gland dysfunction.

Hashimoto’s Thyroiditis

Autoimmune destruction of thyroid causing hypothyroidism.

Secondary Hypothyroidism

Low thyroid hormone due to pituitary dysfunction (low TSH).

Tertiary Hypothyroidism

Low thyroid hormone due to hypothalamus dysfunction (low TRH).

Myxedema Coma

Life-threatening severe hypothyroidism causing hypothermia, hypoventilation, hypoglycemia, and hypotension.

Hyperthyroidism Symptoms

Tachycardia, weight loss, diarrhea, anxiety, hyperreflexia, goiter, exophthalmos.

Hypothyroidism Symptoms

Bradycardia, weight gain, constipation, cold intolerance, fatigue.

Adrenal Medulla

Inner adrenal gland that secretes epinephrine and norepinephrine.

Pheochromocytoma

Rare adrenal medulla tumor causing excessive catecholamine release and severe hypertension.

Adrenal Cortex

Outer adrenal gland that secretes cortisol and aldosterone.

Cortisol

Glucocorticoid that increases blood glucose and suppresses immune/inflammatory response.

Aldosterone

Hormone that promotes sodium and water retention and potassium excretion.

Hypothalamic-Pituitary-Adrenal Axis

CRH → ACTH → Cortisol pathway.

Primary Adrenal Insufficiency (Addison’s Disease)

Autoimmune destruction of adrenal cortex causing low cortisol and aldosterone.

Secondary Adrenal Insufficiency

Low cortisol due to decreased ACTH from pituitary.

Adrenal Crisis

Life-threatening complication of adrenal insufficiency causing dehydration, hyperkalemia, and hypotension.

Hyponatremia

Low sodium in bloodstream.

Hyperkalemia

High potassium in bloodstream.

Cushing’s Syndrome

Excess cortisol, often due to long-term corticosteroid use.

Cushing’s Disease

Excess cortisol due to pituitary tumor producing excess ACTH.

Cushing’s Symptoms

Hyperglycemia, hypertension, moon face, buffalo hump, thin extremities, poor wound healing, thin skin.

Hyperaldosteronism

Excess aldosterone secretion.

Conn’s Syndrome

Primary hyperaldosteronism due to adrenal tumor.

SIADH (Syndrome of Inappropriate ADH)

Excess ADH causing water retention, hyponatremia, concentrated urine, and low serum osmolarity.

Diabetes Insipidus (DI)

Insufficient ADH action causing excessive dilute urine and hypernatremia.

Central (Neurogenic) DI

Low ADH secretion from pituitary.

Nephrogenic DI

Kidneys do not respond to ADH.

Water Deprivation Test

Test used to diagnose diabetes insipidus by assessing urine concentration after fluid restriction.

Anterior Pituitary Hormones

TSH, ACTH, LH, FSH, GH, Prolactin.

Posterior Pituitary Hormones

ADH and Oxytocin.

Amenorrhea

Absence of menstruation.

Exophthalmos

Forward displacement of the eyes seen in Graves disease.

Goiter

Enlargement of the thyroid gland.

Hyperosmolarity

High concentration of solutes in blood.

Hypo-osmolarity

Dilute blood with low solute concentration.

Polyuria

Excessive urination.

Polydipsia

Excessive thirst.