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 Stupor Coma Seizures Nausea Malaise Stupor Coma Seizure Potassium Palpitations Parasthesias Muscle weakness U waves and flattened T waves Palpitations Arrythmias Parasthesias Muscles weakness Peaked T waves and wide QRS Calcium Seizures Tetany Chvostek sign ipsilateral facial muscle contraction caused by tapping the facial nerve Trousseau sign carpopedal spasms by inflating the sphygmomanometer above systolic blood pressure QTc prolongation Nephrolithiasis Polyuria Muscle weakness Bone pain Abdominal pain secondary to bowel hypomotility and constipation Confusion Stupor Coma Shortened QTc interval mnemonic: stones (renal), bones (pain), groans (abdominal pain), thrones (↑ urinary frequency), psychiatricovertones (altered mental status) Magnesium Tetany Torsades de pointes Hypokalemia Hypocalcemia when significant (< 1.2 mg/dL) ↓ deep tendon reflexes Bradycardia Cardiac arrest Hypocalcemia Phosphate Osteomalacia Rickets Nephrolithiasis Metastatic calcifications Hypocalcemia