Nursing Field Notes / Renal + Fluid · Fundamentals of Nursing

Potassium, Sodium & Chloride ⚡

Fluid & Electrolyte Basics I — the three that kill first

NG-088 RENAL + FLUID ADHD-friendly visual edition

We are breaking down the top-tested causes and the critical manifestations of how clients present when electrolytes are out of balance. Some imbalances can be deadly. The MOST deadly conditions are the MOST tested conditions — nursing school exists to make nurses who spot the thing that is not right.

📄 Simple Nursing original — opens in Drive →

⚡ K⁺ PUMPS the heartNormal 3.5–5.0 mEq/L — the narrowest range in the body, so it kills fastest.

🌊 Na⁺ SWELLS with fluidNormal 135–145 mEq/L — sodium problems are brain problems.

🧂 Cl⁻ SHADOWS sodiumNormal 97–107 mEq/L — nearly the same signs as sodium, plus pH.

🚨 NEVER IV push K⁺IV push potassium = cardiac arrest. Always diluted, always a pump, max 10–20 mEq/hr.

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THE GROUND RULES

STEP 1 · HOW TO READ ANY ELECTROLYTE

Learn the reading pattern once and all six electrolytes become the same question.

🧪 Every electrolyte page is the same 5-band scale

Answer first: find the number, then find the band. Anything outside NORMAL gets nursing action. Anything in a CRITICAL band gets a provider call and a cardiac monitor.

🧠 “BAND then PLAN.” Read the number → name the band → the band tells you the plan: replace it, remove it, or stabilize the heart.

💧 The one sentence that explains every cause

“Where fluids flow, electrolytes goooo!”

Any route that moves fluid out of the body moves electrolytes with it — vomiting, diarrhea, NG suction, diuresis, sweating, wound drainage, burns.

🧠 Fluid is the bus, electrolytes are the passengers. Lose the bus, lose the passengers.

🔤 hypo- vs hyper- : decode the word, get the answer

Word part	Means
hypO-	lOw — the O gives it away
hypER-	ovER — the ER gives it away
-kalemia	Kalium = potassium
-natremia	Natrium = sodium
-chloremia	chloride

🧠 hypO = lOw · hypER = ovER. Two letters, and half the electrolyte questions are already narrowed to one column.

🫀 Why these three, and why potassium first

Potassium ⚡ — pumps the heart. The tightest window in the body (3.5–5.0). Small change → lethal rhythm. Answer potassium questions with the monitor.
Sodium 🌊 — swells the body with fluid. Sodium pulls water, so sodium problems become brain problems (edema or shrinkage) → LOC changes & seizures.
Chloride 🧂 — rides with sodium and balances pH. Almost always moves the same direction as Na⁺ and the opposite direction from bicarbonate.

🧠 “K kills, Na confuses, Cl copies.” Potassium stops the heart · sodium scrambles the brain · chloride copies sodium's homework.

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POTASSIUM · K⁺

STEP 2 · PUMPS THE HEART

🚨 PRIORITY electrolyte — both directions are cardiac emergencies, and the fix for each is opposite.

🧪 Potassium value scale

NORMAL 3.5 – 5.0 mEq/LCRITICAL ≤2.5 or ≥6.5

🧠 “3.5 to 5 keeps you alive.” The tightest range in the body — memorize it cold.

⭐ P = Potassium PUMPS the heart

🫀 Runs the electrical impulse of every heartbeat
💪 Runs skeletal muscle contraction & strength
🧠 Runs nerve conduction
🌀 Mostly INSIDE the cell — the serum level is only the small amount outside, which is why it swings so fast

TEST TIP The kidneys are the only real exit for potassium — so renal failure = hyperkalemia almost every time.

🧠 P for Potassium, P for Pump. High pump = the body speeds up and short-circuits · Low pump = everything goes limp and slow.

📉 HYPOkalemia — below 3.5 · everything is LOW & SLOW

Causes — “the D's” (fluid loss = electrolyte loss)

Diarrhea & vomiting / NG suction
Diuretics — loop & thiazide (-ide: furosemide, hydrochlorothiazide)
Diet low in potassium · NPO · alcoholism
DKA & insulin — insulin drives K⁺ into the cell
Aldosterone excess — Adds sodium, Loses potassium

Manifestations (S/S)

🫁 Neuromuscular: SHALLOW respirations — MOST DEADLY, decreased DTR, muscle cramping, flaccid paralysis (paralyzed limbs), fatigue
🚽 GI: constipation, hypOactive bowel sounds, paralytic ileus — ⚠️ priority risk for SBO
🫀 Heart: flat T waves, ST depression & U waves, PVCs, weak pulse

🧠 “LOW K = everything sags.” Sagging T wave, sagging ST segment, sagging gut, sagging limbs, sagging breaths. The U wave is the only thing that pops up.

📈 HYPERkalemia — over 5.0 · everything is HIGH & TIGHT

Causes

🫘 RENAL FAILURE — the #1 cause (no exit door)
🧂 Low aldosterone (Addison's) — Adds sodium, Loses potassium, so losing aldosterone keeps potassium in
💊 K⁺-sparing drugs: spironolactone · -pril ACE inhibitors (lisinopril) · -sartan ARBs (losartan)
💥 Cell death dumps K⁺ out: crush injury, burns, rhabdomyolysis, tumor lysis, hemolysis, old banked blood
🧪 Acidosis — H⁺ moves into the cell, K⁺ moves out
🩸 False high: a hemolyzed specimen or a tight, prolonged tourniquet — redraw before treating a symptom-free client

Manifestations (S/S)

💪 Neuromuscular: increased DTR early, paresthesia (tingling), then paralysis & muscle weakness — “a general feeling of heaviness”
🚽 GI: diarrhea, hyperactive bowel sounds, cramping
🫀 Heart: PEAKED T waves + ST changes → widened QRS, flattened P → V-fib & cardiac arrest; hypotension & bradycardia

🧠 “Murder = hyperkalemia.” High K⁺ is what a lethal-injection drug does. Tight muscles, tall T waves, then the heart quits.

📈 The EKG is the answer to most potassium questions

🧠 “Tall tents mean too much · flat with a U means too few.” Tall tented T = hyper. Flat T with a U-wave tag-along = Under (hypo).

🚨 EMERGENCY ORDER — HYPERkalemia: stabilize → shift → remove

Answer first: calcium gluconate goes FIRST — it does not lower the potassium at all, it protects the heart muscle while the other drugs work.

🫀 STABILIZE — IV calcium gluconate (calcium chloride if central access)
Raises the cardiac threshold so the heart can't fibrillate. Works in minutes, lasts ~30–60 min. Continuous cardiac monitor. It does NOT lower the K⁺ level.

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💉 SHIFT it into the cell — regular INSULIN IV + dextrose (D50)
Insulin pushes K⁺ into cells in ~15–30 min. Always give glucose with it and recheck the blood sugar — hypoglycemia is the expected complication.

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🌬️ SHIFT more — high-dose nebulized albuterol · sodium bicarbonate if the client is acidotic
Also temporary. Shifting buys time; it does not remove one molecule of potassium.

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🚽 REMOVE it — loop diuretic (furosemide) if the kidneys still work · GI binders: sodium polystyrene sulfonate (Kayexalate), patiromer, sodium zirconium cyclosilicate
Binders work over hours — never the answer for a peaked-T-wave emergency.

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🩺 DIALYSIS — the definitive removal
The answer when the client is in renal failure, the K⁺ is severe, or nothing else is holding.

Also do: stop all potassium sources — IV fluids with K⁺, K⁺-sparing diuretics, ACE inhibitors/ARBs, salt substitutes (they are potassium chloride 🧂), and high-K⁺ foods.

🧠 “C BIG K DROP” — Calcium gluconate · Bicarb · Insulin · Glucose · Kayexalate · Diuretic · Dialysis. Say it in order and you have the whole protocol. Calcium is always the C at the front.

💊 EMERGENCY ORDER — HYPOkalemia: replace it safely

🫀 Cardiac monitor FIRST — a low K⁺ with a client on digoxin is a dysrhythmia waiting to happen.

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💧 Check urine output before giving K⁺ — at least 30 mL/hr. No pee, no K⁺.

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🥔 Mild & able to eat → ORAL route: oral KCl with a full glass of water and food (it is a GI irritant) + potassium-rich foods.

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💉 Severe / symptomatic → IV KCl, always diluted, always on an infusion pump, 10–20 mEq/hr max, monitored.

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🧲 Check the magnesium. Potassium will not correct until magnesium is corrected — replace Mg²⁺ too.

🍌Banana

🥑Avocado

🥔Potatowith skin

🥬Spinach

🍊Orange& OJ

🍅Tomato

🫘Beans

🥛Milk

🍈Cantaloupe

🧠 “BAPS & O” — Banana · Avocado · Potato · Spinach · Orange. The same list is what you TAKE AWAY in hyperkalemia.

❌ IV potassium: the four rules that show up on every exam

1. First action = put the client on a heart monitor.
2. NEVER IV push potassium — it causes DEATH. Never IM, never SubQ, never undiluted.
3. 10–20 mEq/hr maximum, always on an IV pump, always diluted.
4. If the client reports burning at the site and the IV is patent → SLOW the infusion rate. Stopping it entirely is the most commonly chosen wrong answer.

🧠 “Potassium takes the slow lane.” Slow bag · slow pump · slow rate. Anything fast about potassium is a wrong answer.

⚖️ Hypo vs hyper potassium — tell them apart

System	📉 HYPOkalemia < 3.5	📈 HYPERkalemia > 5.0
One word	LOW & SLOW · limp	HIGH & TIGHT · then limp
Neuro / muscle	↓ DTR, flaccid paralysis, cramps, fatigue	↑ DTR early, paresthesia → paralysis, heaviness
Respiratory	Shallow respirations — most deadly	Respiratory muscle weakness late
GI	Constipation, hypoactive sounds, ileus → SBO	Diarrhea, hyperactive sounds, cramping
EKG	Flat T · ST depression · U wave	Peaked T · wide QRS · lost P
Worst outcome	PVCs → V-tach, digoxin toxicity	V-fib & cardiac arrest
First move	Monitor + check urine output, then replace	Monitor + IV calcium gluconate

🧠 Gut goes opposite the level in hypo, same as the level in hyper. Low K⁺ = constipated · High K⁺ = diarrhea. If the stem says diarrhea AND peaked T waves, it is hyperkalemia.

🌊

SODIUM · Na⁺

STEP 3 · SWELLS THE BODY WITH FLUID

Sodium is water's magnet — so every sodium problem ends up as a brain problem.

🧪 Sodium value scale

NORMAL 135 – 145 mEq/LCRITICAL <120 or >160

🧠 “135 to 145 keeps the brain alive.” Count it like a phone number: one-three-five, one-four-five.

⭐ S = Sodium SWELLS the body with fluid

Sodium maintains:

🩸 Blood pressure
💧 Blood volume
🧪 pH balance

Water follows salt. Sodium is the main particle outside the cell, so it decides which way water moves across the cell wall — and the cells that mind that shift the most are brain cells inside a rigid skull.

🧠 “Salty = Swollen.” Retain salt → retain water → swollen body, high BP. Sodium and water are on the same team, always.

📉 HYPOnatremia — below 135 · the brain SWELLS

Causes — either lose salt or gain water

💦 Sweating — running in extreme heat
🚰 Excess water intake (water intoxication, over-diluted formula, psychogenic polydipsia)
🧠 SIADH — excess ADH holds water in → dilutes the sodium TEST TIP
🤮 Vomiting & diarrhea
💊 Diuretics & diuresis (thiazides especially)
🧂 Diet low in salt
🫘 Low aldosterone (Addison's) — Adds sodium is what aldosterone should do

Manifestations — “Low & slow, brain on the go”

🧠 Brain: headache = cerebral edema, mental status changes / confusion, seizures & coma
💪 Muscular: fatigue, muscle cramps, weakness
🫁 Respiratory: respiratory arrest in severe cases
🚽 Nausea, vomiting, abdominal cramping

🧠 “No salt, brain swells and stalls.” Low sodium outside → water rushes into brain cells → they swell inside a skull that cannot stretch → headache → confusion → seizure → coma.

📈 HYPERnatremia — over 145 · the body is DRY INSIDE

Causes — either lose water or gain salt

🚱 Low ADH → Diabetes Insipidus (DI) — Dry Inside TEST TIP — huge dilute urine output
💨 Rapid respirations (insensible water loss)
💩 Watery diarrhea
🥤 Loss of thirst / no access to water — the classic older adult or tube-fed client
🧂 High-sodium diet, hypertonic IV fluids, excess salt tabs

Manifestations — “Body = BIG & BLOATED”

🎈 Edema (swollen body)
🟥 Flushed, “red & rosey” skin
💪 Increased muscle tone, twitching, hyperreflexia
👅 Swollen dry tongue, sticky mucous membranes, extreme thirst
🤢 Nausea & vomiting
🧠 Restless, agitated → lethargy, seizures, coma

🧠 “Salty and swollen with a dry tongue.” The outside looks puffy and red, but the cells are shriveled — that mismatch is what makes hypernatremia weird and testable.

🔬 Why sodium is really a brain question — watch the cell

🧠 “Salt sucks water toward it.” Sodium low outside → water goes in → swell. Sodium high outside → water comes out → shrivel. One rule answers every fluid-shift question.

🚨 EMERGENCY ORDER — sodium correction (both directions go SLOW)

📉 HYPOnatremia

Seizure precautions + neuro checks — pad rails, suction & O₂ at the bedside.

Dilutional (SIADH, water excess) → RESTRICT FLUIDS, daily weights, strict I&O.

True salt loss → isotonic 0.9% NS.

Severe & seizing → hypertonic 3% NaCl, ICU, pump, frequent labs.

Correct SLOWLY. Raising sodium too fast causes osmotic demyelination (central pontine myelinolysis) — permanent brain injury.

📈 HYPERnatremia

Neuro checks + seizure precautions — same brain risk, opposite direction.

Give WATER back — oral water first if the client can swallow safely.

IV hypotonic fluid (0.45% NS or D5W) per order; treat the cause — DI, diarrhea, feeds.

Stop the salt: hold high-sodium IVFs, salt tabs, canned/processed foods.

Correct SLOWLY. Dropping sodium too fast pulls water into the brain → cerebral edema.

Both directions: daily weights (1 kg = 1 L), strict I&O, safety/fall precautions, and frequent serum sodium draws while correcting.

🧠 “Fix it fast, the brain won't last.” Whichever way the sodium is wrong, the danger of the treatment is speed. Slow & monitored is always the safe answer.

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CHLORIDE · Cl⁻

STEP 4 · SODIUM'S SHADOW

Learn chloride in 60 seconds: it copies sodium's signs and it controls pH.

🧪 Chloride value scale

NORMAL 97 – 107 mEq/LCRITICAL <80 or >115

🧠 “97 to 107 — one hundred, give or take.” Park it around 100 and adjust ±7–10.

⭐ Cl⁻ is related to sodium — it maintains the same things

🩸 Blood pressure
💧 Blood volume
🧪 pH balance — this is chloride's own job

Chloride is the negative partner that travels with sodium (as salt) and trades places with bicarbonate to keep the blood's pH steady.

🧠 “Cl⁻ is Na⁺'s shadow.” If you know the sodium answer, you know the chloride answer — then add pH.

📉 HYPOchloremia — below 97

NEARLY THE SAME AS LOW SODIUM

💪 Fatigue & muscle cramps
🌡️ Fever — the only difference from low sodium
😵 Weakness, hyperexcitable muscles, tetany-like twitching, shallow respirations if severe

Causes: vomiting & NG suction (losing hydrochloric acid), diuretics, low-salt diet, burns/sweating, low aldosterone.

ACID–BASE Losing HCl from the stomach leaves the blood short of acid → metabolic ALKALOSIS travels with low chloride.

🧠 “Low Cl⁻ = low sodium + a FEVER.” One extra symptom is the whole distinction. Vomiting throws up the acid, so the blood turns alkalotic.

📈 HYPERchloremia — over 107

NEARLY THE SAME AS HIGH SODIUM

👅 Swollen dry tongue
🤢 Nausea & vomiting
🎈 Edema, flushed skin, increased muscle tone, thirst, weakness, lethargy
💨 Deep rapid breathing (Kussmaul) if acidosis is significant

Causes: dehydration/water loss, large volumes of 0.9% normal saline, hypernatremia, kidney disease, hyperparathyroidism, respiratory alkalosis compensation.

ACID–BASE High chloride crowds out bicarbonate → metabolic ACIDOSIS (the normal–anion-gap kind).

🧠 “Chloride UP, bicarb DOWN → acid.” Cl⁻ and HCO₃⁻ sit on a seesaw; whichever one rises pushes the pH the opposite way.

⚖️ The chloride–bicarbonate seesaw (this is the whole pH story)

🧠 “Vomit the acid, go alkalotic.” Vomiting & NG suction pour HCl out of the body → chloride drops, bicarb rises, pH climbs. That is why the NG-suction client gets metabolic alkalosis on every exam.

🩺 EMERGENCY ORDER — chloride

📉 HYPOchloremia (with alkalosis)

Find and stop the loss — antiemetics, review the NG suction order, hold the diuretic per provider.

Replace with 0.9% normal saline — it is literally sodium chloride.

Check K⁺ too — vomiting drops potassium at the same time; replace both.

Watch for tetany & shallow breathing; monitor ABGs and safety.

📈 HYPERchloremia (with acidosis)

Treat the dehydration — free water / hypotonic fluid per order.

Stop the chloride load — reassess large-volume 0.9% NS; a balanced solution (lactated Ringer's) may be ordered instead.

Sodium bicarbonate if the acidosis is significant, per provider.

Monitor LOC, ABGs, I&O and daily weights; low-sodium diet teaching.

🧠 “Saline gives chloride, water takes it away.” Need chloride → 0.9% NS. Too much chloride → free water. That single sentence answers most chloride care questions.

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QUICK RECALL

SAY IT OUT LOUD

🚨 Hyperkalemia orderC BIG K DROP — Calcium gluconate FIRST, then insulin+glucose, albuterol/bicarb, diuretic/Kayexalate, dialysis.

❌ Never push K⁺Diluted · pump · 10–20 mEq/hr · monitor. Burning arm → slow the rate.

🧠 Sodium = brainLow Na⁺ → cells swell → seizures. High Na⁺ → cells shrivel → thirst & agitation. Correct slowly either way.

🧂 Chloride copies sodiumLow Cl⁻ = low Na⁺ signs + fever & alkalosis · High Cl⁻ = high Na⁺ signs & acidosis.

🧾 One-screen number sheet

Electrolyte	Normal (adult)	Below normal	Above normal
Potassium K⁺	3.5 – 5.0 mEq/L	Flat T · U wave · ileus · shallow breaths	Peaked T · wide QRS · diarrhea · arrest
Sodium Na⁺	135 – 145 mEq/L	Cerebral edema · confusion · seizures	Dry swollen tongue · flushed · agitated
Chloride Cl⁻	97 – 107 mEq/L	Low-Na⁺ signs + fever · alkalosis	High-Na⁺ signs · acidosis

REMEMBER Potassium Pumps the heart · Sodium Swells the body with fluid · Chloride Copies sodium.

🎯 Cover & check — 8 rapid-fire questions

Q1: The K⁺ is 7.1 with peaked T waves. What is the FIRST drug?

IV calcium gluconate — it stabilizes the myocardium. It does not lower the potassium; insulin + dextrose does the shifting next.

Q2: A client on a KCl infusion reports burning at the IV site and the line is patent. What do you do?

SLOW the infusion rate. (Stopping it is the most commonly chosen wrong answer.) Never push, never exceed 10–20 mEq/hr, always on a pump.

Q3: Which hypokalemia sign is the MOST deadly?

Shallow respirations — respiratory muscle weakness. Also watch flaccid paralysis, paralytic ileus (risk for SBO), and flat T waves with U waves.

Q4: Name the #1 cause of hyperkalemia and the memory trick for aldosterone.

Renal failure. AL = Adds sodium, Loses potassium — so LOW aldosterone means the body keeps potassium (hyperkalemia) and dumps sodium.

Q5: Na⁺ is 118 and the client is confused. What is the priority nursing action?

Seizure precautions and neuro checks — low sodium causes cerebral edema. Restrict fluids if dilutional/SIADH; hypertonic 3% saline only for severe symptomatic cases, corrected slowly.

Q6: Why must sodium be corrected slowly in BOTH directions?

Raising it too fast → osmotic demyelination (central pontine myelinolysis). Lowering it too fast → cerebral edema. The brain cannot tolerate rapid osmotic shifts.

Q7: What single symptom separates hypochloremia from hyponatremia?

Fever. Otherwise they look nearly identical (fatigue and muscle cramps). Low chloride also travels with metabolic alkalosis from vomiting/NG suction.

Q8: A client vomiting for 3 days has Cl⁻ 88. What acid–base picture do you expect and what fluid?

Metabolic alkalosis from losing hydrochloric acid. Expect 0.9% normal saline to replace sodium chloride and volume — and check the potassium, which is falling too.