Electrolyte Disturbances

Snapshot

A 22-year-old man is brought to the emergency department by his friend after witnessing him fall to the ground and shaking his upper and lower extremities. His friend reports that he prevented the patient from hitting his head. Prior to developing this symptom the patient felt numbness in his hands and feet, muscle cramps, and mild palpitations. Medical history is significant for DiGeorge syndrome. On physical exam, there is facial muscle twitching with ipsilateral tapping of the facial nerve anterior to the ear. An electrocardiogram shows QTc prolongation. Laboratory testing is significant for an ionized calcium level of 4.0 mg/dL. (Provoked seizure secondary to hypocalcemia)

Introduction

Electrolyte Disturbances
Electrolyte	Low Serum Concentration	High Serum Concentration
Sodium	StuporComaSeizures NauseaMalaise	StuporComaSeizure
Potassium	PalpitationsParasthesiasMuscle weaknessU waves and flattened T waves	PalpitationsArrythmiasParasthesiasMuscles weaknessPeaked T waves and wide QRS
Calcium	SeizuresTetanyChvostek sign ipsilateral facial muscle contraction caused by tapping the facial nerveTrousseau sign carpopedal spasms by inflating the sphygmomanometer above systolic blood pressureQTc prolongation	NephrolithiasisPolyuriaMuscle weaknessBone painAbdominal painsecondary to bowel hypomotility and constipationConfusionStuporComaShortened QTc intervalmnemonic: stones (renal), bones (pain), groans (abdominal pain), thrones (↑ urinary frequency), psychiatric overtones (altered mental status)
Magnesium	TetanyTorsades de pointesHypokalemiaHypocalcemiawhen significant (< 1.2 mg/dL)	↓ deep tendon reflexesBradycardiaCardiac arrestHypocalcemia
Phosphate	OsteomalaciaRickets	NephrolithiasisMetastatic calcificationsHypocalcemia