Perioral tingling, cramps, tetany, Chvostek and Trousseau
Fluid, Electrolyte & Acid-Base · Topic 2 of 23
Hypocalcemia
A post-thyroidectomy patient reports tingling around their mouth and fingertips.
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Hypocalcemia
Na⁺SodiumWNL
K⁺PotassiumWNL
Cl⁻ChlorideWNL
Ca²⁺CalciumPriority
Mg²⁺MagnesiumWNL
PO₄³⁻PhosphateH
ECFVolume (ECF)WNL
pHpHWNL
Bedside monitor · pattern
Hypocalcemia
Low ionized calcium removes a membrane-stabilizing brake, so nerves and muscles fire too easily.
Direct physiologyThreshold falls→Spontaneous firing→QT lengthens
ECG responseQT interval lengthening
QTc 479 msThe QT is stretching. It is not yet a torsades substrate, but it is heading there — and any QT-prolonging drug added now stacks on top of the electrolytes.
Neuronal excitabilityHyperexcitable
SuppressedBalancedHyper
PerfusionEuvolemic
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Extracellular volume at baseline. The dashed line marks euvolemia.
What the nurse would notice
Hypocalcemia across body systems
Also on this panel
Prolonged QT, dysrhythmia, weak contraction
Laryngospasm and bronchospasm when severe
Irritability, anxiety; seizures when severe
Teaching model, not a clinical calculator. Patterns show high-yield directional relationships under the stated assumption. Real symptoms, ranges and treatment depend on cause, acuity, comorbidities and local protocols.
Signs & symptoms
Present on this panel. Tap any sign to see which values produce it.
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Tap to start15 cards · about 6 min · +45 XP
Fluids & electrolytes · Ca²⁺
Hypocalcemia
Too little calcium in the blood. Nerves and muscles turn twitchy — tingling first, then cramps and tetany — and the airway can clamp shut.
Lead II · day 2 after thyroid surgery · example patient9.5Ca²⁺ mg/dL
Long QT — a stretched ST segment pushes the T wave late · risk of ventricular dysrhythmias
01 · The numberCa²⁺ below 8.5
mg/dL · normal 8.5 – 10.5
02 · The dangerLaryngospasm
Inspiratory stridor (crowing on breathing in) → call for help and support the airway
03 · The fixGive IV calcium slowly
Calcium gluconate over 10 – 20 min, on a pump, on a cardiac monitor — never a rapid IV push
01
Two bedside signs. Tap to test them.
Try itChvostek sign
Trousseau sign0:00
Illustration. Chvostek: tap the facial nerve just in front of the ear. Trousseau: a BP cuff above systolic for 3 minutes. Trousseau is the more specific sign — a positive one is a report-now finding.
02
What causes it
Watch forClassic exam cause: thyroid or parathyroid surgery
Parathyroids not working
Thyroid or parathyroid surgerydrop comes 24 – 48 h afterHypoparathyroidismlow Ca²⁺, high phosphorusLow magnesiumblocks PTH
Not enough absorbed or kept
Vitamin D deficiencyKidney diseasehigh phosphorus
Calcium bound up
Massive blood transfusioncitrate binds calciumAlkalosismore calcium sticks to albumin
After neck surgery, ask about tingling around the mouth and fingers for the first 24 – 48 h.
03
What you'll see
SignsHallmark: nerves and muscles overexcited (neuromuscular irritability)
Numbness and tingling around the mouth, fingers and toes earlyparesthesias — usually the first thing they notice
Muscle cramps and spasms early
Positive Chvostek signtap the facial nerve just in front of the ear → the face twitches
Positive Trousseau signBP cuff inflated above systolic for 3 minutes → the hand and wrist spasm
Hyperactive deep tendon reflexes
Tetany (sustained, painful muscle spasm) late
Laryngospasm (stridor) · seizures latewhen calcium falls far or fast
The signs spell CATs go numb:CConvulsions (seizures)AArrhythmias — the long QTTTetany — Chvostek and Trousseau signssSpasms and stridor (laryngospasm)numbNumbness and tingling around the mouth, fingers and toesChvostek is positive in up to 10% of healthy people, so neither sign alone proves it — Trousseau is the more specific.
04
Labs & diagnostics
CheckSerum Ca²⁺ < 8.5 mg/dL
Serum Ca²⁺ below 8.5 mg/dLnormal 8.5 – 10.5 · below 7 can bring hyperreflexia, tetany, laryngospasm or seizures
Check albumin — low albumin lowers total calcium, not the active kindadd about 0.8 mg/dL per 1 g/dL albumin below 4 · or check ionized Ca²⁺ (below about 4.7 mg/dL confirms it)
Check magnesiumlow Mg keeps the calcium from staying corrected
ECG: prolonged QT intervalraises the risk of dangerous ventricular dysrhythmias · not the same as hyperkalemia, which peaks the T waves and widens the QRS
Phosphorus highin hypoparathyroidism and kidney disease
pH · alkalosis?tetany can appear even when total calcium looks near normal
Lab ranges vary a little (e.g., 8.6 – 10.2 mg/dL) — use your facility's range.
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Red flags
Act nowStridor or noisy, crowing breathing report nowlaryngospasm — call for help, support the airway
Seizure report nowprotect the airway · seizure precautions
Tetany or a positive Trousseau sign report now
New long QT or dysrhythmia on the monitor report now
Bradycardia or hypotension during IV calcium holdstop the infusion and notify
Burning or swelling at the IV site holdstop the infusion — extravasation causes tissue necrosis
Patient on digoxin needs IV calciumcan trigger dysrhythmias — give it slowly on continuous ECG
06
Treatment: protect the airway, then replace calcium slowly
In this orderIV calcium slowly, on a pump, on a monitor — never a rapid push
Do right now
1
→Protect the airwaystridor → call for help
2
→Start cardiac monitoringcontinuous, before IV calcium
3
→IV calcium gluconateslowly, on a pump — as ordered
4
Seizure precautionspadded side rails, suction
IV calciumSymptomatic · acute
Calcium gluconate 10% IV
Over about 10 – 20 minutes on a pump, with continuous ECG monitoring.
Never a rapid IV pushPeripheral IVGluconate, not chloride
Calcium gluconate
Calcium chloride belongs in a central line — it irritates veins far more.
Extravasation → tissue necrosisMagnesiumReplace it too
Magnesium
Calcium won't stay corrected until magnesium is replaced.
Check Mg with every low Ca²⁺Oral calciumLong term
Oral calcium Vitamin D
Plus calcium-rich foods — dairy, green leafy vegetables.
Report tingling or crampsMore detail
Label limit for a diluted bolus: no faster than 200 mg/minute in adultsthe calcium gluconate label — the usual order runs over 10 – 20 min
Keep emergency airway equipment at the bedsidefor any patient at risk of laryngospasm
07
Nursing priorities
In orderProtect the airwaystridor = laryngospasm · emergency airway equipment at the bedside
Continuous cardiac monitoringprolonged QT · dysrhythmias · during every IV calcium dose
Give IV calcium gluconate slowly on a pumpwatch the IV site and the heart rate
Seizure precautionspadded side rails, suction at the bedside
After thyroid or parathyroid surgery: ask about tingling24 – 48 h · check Chvostek and Trousseau
Check magnesium and albuminthey change what the number means — and whether it will correct
08
Hypo or hyper calcium?
| Level | Ca²⁺ below 8.5 mg/dL |
|---|---|
| Nerves & muscles | Excited — tingling, cramps, tetany |
| Reflexes | Hyperactive |
| Classic signs | Chvostek and Trousseau signs |
| ECG | Prolonged QT |
| Danger | Laryngospasm · seizures |
| Fix | IV calcium gluconate — slowly, on a pump |
09
Teach your patient
DischargeTake calcium with vitamin D as prescribed
Eat calcium-rich foodsdairy, green leafy vegetables
Report tingling around the mouth or fingers, or muscle crampsthe early warning that calcium is dropping
Keep lab follow-upscalcium — and magnesium, which has to be normal for calcium to stay up
Low calcium makes nerves and muscles twitchy — tingling, cramps, tetany, a closing airway, a long QT. Give IV calcium slowly, on a pump, on a monitor — never a rapid push.
Sources · Ranges, signs and IV calcium checked against OpenStax Medical-Surgical Nursing 10.3, OpenStax Clinical Nursing Skills 19.3, OpenStax Fundamentals of Nursing 20.1, the Merck Manual Professional, the calcium gluconate injection label (DailyMed) and the Society for Endocrinology emergency guidance on acute hypocalcaemia. Chvostek drawing from Gray's Anatomy, “The nerves of the scalp, face, and side of neck” (public domain) and Loomis & Thompson, “Facial spasm (Chvostek's symptom)” (1897, public domain); Trousseau hand from Sachs, “Position of hands in the spasm of tetany” (1905, public domain) and “Human right hand sideways” (Ewithu, Wikimedia Commons, CC0). Typical adult values — follow your protocol.
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Hypocalcemia
A post-thyroidectomy patient reports tingling around their mouth and fingertips. The vitals look stable — but neuromuscular crisis is minutes away if you miss the calcium connection.
Normal total serum calcium is 9.0–10.5 mg/dL (ionized: 4.5–5.5 mg/dL). Hypocalcemia occurs below these thresholds and most commonly follows thyroid/parathyroid surgery, vitamin D deficiency, hypoparathyroidism, or massive blood transfusions (citrate binds calcium). Calcium stabilizes nerve and muscle cell membranes. When calcium drops, sodium channels open more easily, making neurons hyperexcitable — this is why the hallmark presentation is neuromuscular irritability: perioral numbness, tingling in fingers and toes, muscle cramps, and carpopedal spasm. Untreated, it progresses to laryngospasm, seizures, and prolonged QT interval leading to cardiac arrest. Two bedside assessment signs are critical: Trousseau's sign (inflate a BP cuff above systolic for 3 minutes → carpal spasm indicates positive) and Chvostek's sign (tap facial nerve anterior to the ear → ipsilateral facial twitching). IV calcium gluconate is the standard replacement for symptomatic hypocalcemia — administered slowly via pump, never pushed rapidly, because fast infusion can cause cardiac arrest. Monitor the ECG continuously during infusion. Alkalosis worsens hypocalcemia by increasing calcium binding to albumin, reducing the ionized (active) fraction.
Key Distinctions
Don't confuse Trousseau's (BP cuff → hand spasm) with Chvostek's (facial tap → twitch) — Trousseau's is more reliable and specific. Students mix up hypocalcemia (increased neuromuscular excitability, prolonged QT) with hyperkalemia (also cardiac but shows peaked T waves, wide QRS). Remember that low albumin gives a falsely low total calcium — always check ionized calcium or correct for albumin before interpreting.
Clinical Pearl
Think "CATs go numb": Convulsions, Arrhythmias (prolonged QT), Tetany, Spasms and numbness. Trousseau's = BP Trouser on the arm; Chvostek's = Cheek tap.
Knowledge Check
3 quick questions on the must-knows for this topic.
Question 1 of 3
Hypocalcemia produces which neuromuscular state?
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Go further
- SimulatorFluid & Electrolyte SimulatorChange one lab. Watch the whole patient respond. Sodium, potassium, calcium, magnesium, pH and volume, all linked — with a live ECG and an IV pole where every bag runs.
- GuideThe 6 Electrolyte Relationships Every Nurse Gets Tested On (Mg–K, Ca–PO₄, pH–K and More)Why potassium will not correct until magnesium does, why calcium and phosphate move in opposite directions, how pH moves potassium and ionized calcium, why sodium is a water problem, and why low potassium makes digoxin dangerous — with the mechanism and the nursing move for each, and a simulator to break them on purpose.
- Commonly confusedHypocalcemia vs HypercalcemiaTrousseau and Chvostek vs lethargy and stones — opposite calcium, opposite excitability.
- GuideFluid and Electrolyte NCLEX Questions: The 7 Patterns the Exam Keeps TestingThe priority is the organ, not the number. Anything changing the ECG comes first. Magnesium before potassium and calcium. Volume before the electrolyte. The lab that is lying. Slow is the rule for correction. The assessment that gates the drug. Learn the seven patterns and the individual questions stop being surprising.
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