53. Hypocalcemia

Hypocalcemia: total serum calcium concentration < 8.5 mg/dL (< 2.12 mmol/L), or ionized (free) calcium concentration < 4.65 mg/dL (< 1.16 mmol/L) [1]

Severe hypocalcemia: total serum calcium concentration ≤ 7.5 mg/dL (< 1.9 mmol/L), or ionized (free) calcium concentration < 3.6 mg/dL (< 0.9 mmol/L) [2]

Factitious hypocalcemia: an asymptomatic decrease in total calcium with a normal ionized Ca2+ level (typically occurs due to low serum protein levels)

Loop diuretics increase renal calcium excretion.

Calcitonin

Bisphosphonates

Tetany: increased neuromuscular excitability (when caused by respiratory alkalosis = hyperventilation-induced tetany)

• Paresthesias: typically tingling or pins-and-needles sensation in extremities and/or in the perioral area

• Spasms (e.g., carpopedal spasm , bronchospasm or laryngospasm ), and cramps (possible in any muscle)

• Stiffness, myalgia

• Maneuvers to elicit latent tetany on physical exam

  • Chvostek sign: short contractions (twitching) of the facial muscles elicited by tapping the facial nerve below and in front of the ear (∼ 2 cm ventral to the ear lobe) [1]

  • Trousseau sign: ipsilateral carpopedal spasm occurring several minutes after inflation of a blood pressure cuff to pressures above the systolic blood pressure [1]

Seizure: may be the initial or only symptom [14]

Congestive heart failure —> Hypocalcemia may lead to myocardial dysfunction

Hypotension

Cardiac arrhythmias (symptoms may include palpitations, irregular pulse, syncope)