Nursing Field Notes / Endocrine · Hormone Hall of Fame 3 of 3 · Med-Surg: Endocrine

🩸 ENDOCRINE SET NG-278 Hormones I NG-279 Hormones II NG-280 Hormones III NG-281 Pituitary Disorders NG-282 SIADH vs DI (1) NG-283 SIADH vs DI (2)

Hormone Hall of Fame III 🎩

Adrenal cortex · adrenal medulla · ovaries · testes

NG-280 ENDOCRINE · PART 3 OF 3 ADHD-friendly visual edition

The last stop in the series is the steroid half of the endocrine system. Two small triangular glands sitting on the kidneys handle salt, sugar, sex and shock — and the gonads finish the job. These are the hormones behind Addison, Cushing, Conn, phaeochromocytoma and every steroid taper you will ever hang, so this is the page that pays off later.

🎩 Salt · Sugar · Sex · ShockOutside in: aldosterone → cortisol → androgens → epi/norepi.

🧂 AldosteroneSave salt, spend potassium. LOW in Addison. HIGH in Conn.

☁️ CortisolKeeps glucose up · anti-inflammatory · immune suppressing. HIGH in Cushing.

⚡ Medulla = a nerveEpi & norepi fire in seconds — the pituitary is not involved.

🎩

THE ADRENAL GLAND

STEP 1 · FOUR LAYERS

One gland, two completely different organs stacked together: a steroid factory wrapped around a nerve ending.

🔬 Master diagram — the gland and its four zones

zona glomerulosa · aldosterone zona fasciculata · cortisol zona reticularis · androgens medulla · epi & norepi

🧠 "GFR — Go Find Rex, and Make Good Sex." Glomerulosa/Fasciculata/Reticularis, making Mineralocorticoids, Glucocorticoids, Sex hormones. Then the medulla underneath for shock.

🧬 Why the medulla behaves so differently

The cortex develops from ordinary gland tissue and makes steroids from cholesterol — slow, gene-level effects. The medulla develops from nervous tissue and its cells are modified sympathetic neurons.

So the medulla answers to a nerve impulse, not to ACTH, and its hormones work in seconds, not hours.

🧠 "The medulla is a nerve ending that learned to shout into the bloodstream."

🧪 Everything the cortex makes starts as cholesterol

Aldosterone, cortisol and the adrenal androgens are all steroids cut from the same cholesterol backbone. That gives them shared properties:

They are fat-soluble, so they cross membranes and act on DNA — slow onset, long duration.
They feed back and shut off the pituitary, which is why exogenous steroids suppress the adrenal glands.
At high enough doses each one starts to spill over into the others' effects — high-dose cortisol also holds sodium and dumps potassium.

🧠 Same backbone = overlapping side effects. That single fact explains most of steroid pharmacology.

🧂

THE CORTEX — SALT, SUGAR, SEX

STEP 2 · STEROIDS

Three hormone families from three layers, in the order you meet them from the outside in.

🧂 Aldosterone — the salt hormone

Source: Adrenal cortex — zona glomerulosa
Target: Kidney — distal tubule and collecting duct
Effect: Increases sodium retention (water follows) and increases potassium secretion into the urine. Net result: blood volume and blood pressure rise
Trigger: Low sodium · low blood pressure or volume · stress · high serum potassium · angiotensin II

Aldosterone is the only hormone here that the pituitary does not really control — it answers to RAAS and potassium. Levels are low in Addison disease — hence the low sodium, high potassium and hypotension. Levels are high in Conn syndrome (primary hyperaldosteronism) — hence hypertension with a stubbornly low potassium.

🧠 "Aldosterone = save salt, spend potassium." Sodium and potassium always move in opposite directions here.

🔬 RAAS — the circuit aldosterone belongs to

LINKS OUT Every antihypertensive that ends in -pril blocks the lung step; every one ending in -sartan blocks the receptor; spironolactone blocks aldosterone at the tubule and is therefore potassium-sparing.

☁️ Cortisol — the stress steroid

Source: Adrenal cortex — zona fasciculata
Target: Almost every tissue
Effect: Keeps blood glucose up between meals by making new glucose from protein and fat. Anti-inflammatory and immune-suppressing. Helps maintain blood pressure and vascular tone. In excess: thins skin and bone, wastes muscle, redistributes fat centrally
Trigger: Stress of any kind · hypoglycemia · ACTH · the early-morning peak of the body clock

Cortisol is the hormone you must never stop abruptly. Levels are high in Cushing syndrome and low in Addison disease. The commonest cause of Cushing syndrome overall is exogenous steroid therapy, not a tumor.

🧠 "Cortisol keeps you going and quietly bills you for it." Sugar up, immunity down, protein and bone spent.

🔬 Cortisol across 24 hours — and what it does to each system

🔬 Too much vs too little — one picture

🧠 "CUSHing = CUSHions everywhere" (moon face, hump, trunk). "ADDison = ADD salt and ADD color" (salt craving and bronzed skin).

🧪 The lab mirror

🧠 "Cushing pushes everything up except potassium. Addison drops everything except potassium." Potassium is always the odd one out because aldosterone moves Na⁺ and K⁺ in opposite directions.

🧬 Adrenal androgens — the third layer

Source: Adrenal cortex — zona reticularis
Effect: Weak male-pattern hormones (mainly DHEA). Minor in adult men, where the testes dominate. In women they are the main source of androgen — responsible for pubic and axillary hair
Trigger: ACTH

When these run high — an adrenal tumor, or congenital adrenal hyperplasia — a woman develops hirsutism, acne, deepening voice and menstrual irregularity.

🧠 The layer you forget until a woman presents with a beard.

🚨 Addisonian crisis — the emergency version

An acute, total loss of cortisol. Triggered by infection, surgery, trauma, or abruptly stopping a steroid.

Profound hypotension and shock that responds poorly to fluids alone.
Severe weakness, nausea, vomiting, abdominal or flank pain, fever.
Labs: Na⁺ low, K⁺ high, glucose low, sometimes high calcium.
Treatment is IV fluids and IV glucocorticoid replacement, urgently, with continuous monitoring. Do not delay steroid replacement waiting on test results.

🧠 "No cortisol = no blood pressure." Cortisol is what lets catecholamines work on the vessels — without it, pressors underperform.

⚡

THE MEDULLA — SHOCK

STEP 3 · SECONDS

The only endocrine gland wired directly to a nerve.

🔬 Fight or flight, mapped on the body

⚡ Epinephrine & norepinephrine

Source: Adrenal medulla (chromaffin cells)
Target: Adrenergic receptors throughout the body
Effect: Sympathetic nervous system stimulation. Heart rate and contractility up, bronchodilation, pupils dilate, glucose released, blood shunted to skeletal muscle, digestion halted. Used clinically in shock and anaphylaxis
Trigger: The fight-or-flight response — direct sympathetic nerve stimulation

Rough division of labor: epinephrine hits beta receptors hard (heart and lungs), norepinephrine is more alpha (vasoconstriction, blood pressure).

🧠 "Epi runs the engine, Norepi squeezes the pipes."

⭐ Phaeochromocytoma — when the medulla will not stop

A catecholamine-secreting tumor of the medulla. Classic picture: episodic, severe hypertension with the "5 Ps".

PPressure — paroxysmal, dangerously high BP

PPain — pounding headache

PPerspiration — drenching sweats

PPalpitations — tachycardia

PPallor — vasoconstricted, cold, anxious

Never palpate the abdomen deeply if this is suspected — pressing on the tumor can trigger a catecholamine surge and a hypertensive crisis.

🧠 Hands off the belly. That single rule is the most commonly tested nursing action for this diagnosis.

📋 Cortex vs medulla, side by side

🧂 CORTEX (outer)	⚡ MEDULLA (inner)
Gland tissue	Nerve tissue
Controlled by ACTH and RAAS	Controlled by sympathetic nerves
Makes steroids from cholesterol	Makes catecholamines from tyrosine
Acts over hours to days	Acts in seconds
Essential for life — losing it is fatal without replacement	Survivable without it
Aldosterone · cortisol · androgens	Epinephrine · norepinephrine

🧬

THE GONADS

STEP 4 · REPRODUCTION

FSH and LH from Part 1 finally arrive somewhere — here is what they find.

🔬 Ovary and testis, cut open

🌸 Estrogen & progesterone

Source: Ovaries (and the placenta in pregnancy; small amounts from adrenal androgens converted in fat)
Effect: Control the changes in the endometrium across the menstrual cycle. Estrogen builds the lining and drives female secondary sex characteristics, bone density and the growth spurt; progesterone maintains the lining, quiets the uterus and supports a pregnancy
Trigger: Fluctuating levels of FSH and LH from the anterior pituitary

The corpus luteum — the leftover follicle after ovulation — is the progesterone source in the second half of the cycle. When it dies, progesterone drops and the lining sheds.

🧠 "Estrogen builds the nest, progesterone keeps it." Pro-gestation = pro-pregnancy.

♂️ Testosterone

Source: Testes — Leydig cells
Effect: Sperm production, growth of facial and chest hair, muscle mass, bone density, deeper voice, libido
Trigger: LH from the anterior pituitary. FSH separately drives the Sertoli cells that nurse the sperm

🧠 "LH = Leydig Hormone. FSH = Fertility/Sertoli Helper." Two hormones, two cell types, one testis.

✅ Why this matters at the bedside

Chronic illness, chemotherapy and opioids suppress the GnRH pulse — expect low libido, amenorrhoea and infertility, and normalize the conversation about it.
Low estrogen after menopause accelerates bone loss — a major fall and fracture risk factor in older women.
Prolactin-raising drugs (antipsychotics, metoclopramide) suppress FSH and LH — causing galactorrhoea, amenorrhoea and sexual dysfunction, and a common reason patients stop taking them.

🧠 Reproductive hormones are the first thing the body switches off when it is sick. That is a clue, not an incidental finding.

📋 Part 3 at a glance

Hormone	Source	Effect on tissue	Stimulus for release
Aldosterone	Adrenal cortex (glomerulosa)	↑ sodium retention, ↑ potassium secretion → BP up. Low in Addison	Low sodium · low BP · stress · high K⁺ · angiotensin II
Cortisol	Adrenal cortex (fasciculata)	Keeps glucose up between meals; anti-inflammatory; suppresses immunity. High in Cushing	Stress · hypoglycemia · ACTH
Adrenal androgens	Adrenal cortex (reticularis)	Weak male hormones; main androgen source in women	ACTH
Epinephrine & norepinephrine	Adrenal medulla	Sympathetic stimulation; used for shock and anaphylaxis	Fight-or-flight — direct nerve stimulation
Estrogen & progesterone	Ovaries	Control endometrial changes during the menstrual cycle	Fluctuating FSH & LH
Testosterone	Testes	Sperm production, facial and chest hair, muscle and bone	LH

⚡

QUICK RECALL

SAY IT OUT LOUD

🎩 Salt · Sugar · Sex · ShockOuter to inner. GFR then medulla.

🧂 Save salt, spend K⁺Aldosterone in one line. Low in Addison, high in Conn.

☁️ Cushing = cushionsMoon face, hump, trunk, striae. Addison = salt craving & bronze.

⚡ 5 PsPressure · Pain · Perspiration · Palpitations · Pallor. Don't palpate.

⚠️ Five traps from this page

ACTH controls the cortex, not the medulla. A pituitary problem cannot cause a catecholamine problem.
Cushing's commonest cause is a prescription — long-term steroid therapy, not a tumor.
Addison's labs are the mirror of Cushing's: Na low / K high / glucose low, versus Na high / K low / glucose high.
Do not deeply palpate the abdomen in suspected phaeochromocytoma.
Steroids must be tapered. Exogenous cortisol shuts the whole axis down; abrupt withdrawal is an adrenal crisis.

🔗 The rest of the set

NG-278 · Hall of Fame I — hypothalamus, anterior pituitary, pancreas.
NG-279 · Hall of Fame II — posterior pituitary, thyroid, parathyroid, pineal, thymus.
NG-281 · Pituitary Disorders — GH excess and deficiency, hypopituitarism, prolactinoma.
NG-282 · SIADH vs DI (1) · NG-283 (2).

🎯 Cover & check — 10 rapid-fire questions

Q1: Name the adrenal layers from outside in and what each makes.

Capsule, zona glomerulosa (aldosterone — salt), zona fasciculata (cortisol — sugar), zona reticularis (androgens — sex), then the medulla (epinephrine and norepinephrine — shock).

Q2: What does aldosterone do to sodium and potassium?

Retains sodium (and water follows, raising blood volume and pressure) and secretes potassium into the urine. Save salt, spend potassium.

Q3: Your patient with Addison disease has a sodium of 128 and a potassium of 5.9. Does that fit?

Yes. Aldosterone is low, so sodium is lost and potassium is retained. Expect hypotension, weight loss, weakness, salt craving and hyperpigmentation as well.

Q4: Why do people with Addison disease get bronzed skin?

In primary adrenal failure the pituitary pours out ACTH trying to stimulate a dead gland. ACTH is cut from the same parent molecule as melanocyte-stimulating hormone, so very high ACTH darkens the skin — especially in creases, scars and gums.

Q5: Which is more common — Cushing from a tumor, or from a prescription?

From a prescription. Long-term exogenous glucocorticoid therapy is by far the commonest cause of Cushing syndrome.

Q6: Why does cortisol raise blood glucose?

It drives gluconeogenesis — making new glucose from protein and fat — and reduces peripheral insulin sensitivity, so glucose stays available for the brain during a prolonged stressor.

Q7: A patient with suspected phaeochromocytoma is admitted. Name the one assessment you avoid, and why.

Deep abdominal palpation. Compressing the tumor can release a bolus of catecholamines and precipitate a hypertensive crisis.

Q8: Which hormone triggers testosterone release, and from which cells?

LH, acting on the Leydig cells of the testis. FSH acts separately on Sertoli cells to support sperm production.

Q9: What produces progesterone after ovulation, and what happens when it stops?

The corpus luteum — the remains of the ruptured follicle. If no pregnancy occurs it degenerates, progesterone falls, and the endometrial lining is shed as menses.

Q10: Why does an adrenal crisis cause hypotension that fluids alone struggle to fix?

Cortisol is permissive for catecholamines — without it, blood vessels do not respond normally to epinephrine and norepinephrine. Volume alone does not restore vascular tone; glucocorticoid replacement is needed urgently alongside IV fluids.