Hypocalcemia: Difference between revisions
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==Background== | ==Background== | ||
===Serum Levels=== | ===Serum Levels=== | ||
* | ''Normal value ranges may vary among different laboratories (see examples below)'' | ||
* | *Harbor-UCLA low: <8.9<ref>Harbor-UCLA computer system accessed 08/15/2019</ref> (Ionized: <2.0 ionized) | ||
**UCSF low: <4.8 mg/dL or <1.20 millimol/L<ref>https://www.ucsfhealth.org/tests/003486.html</ref> | |||
*Critical low: <6.6 (<1.5 ionized) | |||
*Correct for hypoalbumimia | *Correct for hypoalbumimia | ||
Revision as of 23:40, 15 August 2019
Background
Serum Levels
Normal value ranges may vary among different laboratories (see examples below)
- Harbor-UCLA low: <8.9[1] (Ionized: <2.0 ionized)
- UCSF low: <4.8 mg/dL or <1.20 millimol/L[2]
- Critical low: <6.6 (<1.5 ionized)
- Correct for hypoalbumimia
- Corrected Ca = (0.8 *(Normal Alb - Patient's Alb)) + Serum Ca
Fraction[3]
- 15% bound to anions (phosphate, lactate, citrate)
- 40% bound to albumin
- 45% free (regulated by PTH, Vit-D)
Causes
- Misc
- Shock
- Sepsis
- Pancreatitis
- Hypomag
- Rhabdo (phosphate overload)
- Massive transfusion
- Systemic Hydrofluoric Acid toxicity
- DiGeorge syndrome
- Decreased absorption
- Increased excretion
- Endocrine
- Drugs
- Cimetidine
- Phenytoin
- Lasix, loop diuretics
- Norepinephrine
- Glucagon
- Glucocorticoids
- Magnesium sulfate
- Nitroprusside
Clinical Features
- Paresthesias (mouth, fingertips)
- ↑ DTRs
- Cramps
- Weakness
- Confusion
- Seizures
- Chvostek/Trousseau signs, Tetany
- Hallucinations
- Laryngospasm
- Bronchospasm
- Cardiac dysrhythmias
Differential Diagnosis
Jaw Spasms
- Acute tetanus
- Akathisia
- Conversion disorder
- Drug toxicity (anticholinergic, phenytoin, valproate, carbamazepine)
- Dystonic reaction
- Electrolyte abnormality
- Hypocalcemic tetany
- Magnesium
- Mandible dislocation
- Meningitis
- Peritonsillar abscess
- Rabies
- Seizure
- Strychnine poisoning
- Stroke
- Temporomandibular disorder
- Torticollis
Evaluation
ECG
- QT Prolongation via increasing the ST length
- Only hypothermia and hypocalcemia prolong QT this way
Trousseau's Sign (Mod to high SN and SP)
- Inflate BP cuff for 2-3 mins
- Positive = Muscle contractions of the hand and wrist
Chvostek's Sign (Low SN and SP)
- Tapping on the face just anterior to the ear and just below the zygomatic bone
- Positive = Ipsilateral facial twitching
Labs
- BMP
- Mag, Phos
- PTH (secondary hyperparathyroidism)
Management
Avoid empiric treatment in patients taking digoxin due to risk for Stone Heart
- Asymptomatic
- Calcium gluconate 1 gm PO Q6hrs
- Vitamin D (calcitriol) 0.2 mcg BID
- Symptomatic
- Calcium gluconate/chloride 10mL of 10% soln IV over 10min
- Correct hypomag at same time (otherwise PTH is inhibited)
- Avoid phenothiazine antipsychotics (may precipitate extrapyramidal symptoms)
- Avoid furosemide (may worsen hypocalcemia)
Disposition
- Admit all symptomatic patients
See Also
References
- ↑ Harbor-UCLA computer system accessed 08/15/2019
- ↑ https://www.ucsfhealth.org/tests/003486.html
- ↑ Yu, AS. Relation between total and ionized serum calcium concentrations. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on October 6th, 2016.)
Video
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