RFT – Calcium

MILD and/or CHRONIC HYPOCALCEMIA

ABCs

  • Asymptomatic OR adjusted calcium between 1.9–2.0 mmol/L
  • Assess symptoms and vitals
  • Order ECG ->
    • QTc prolongation primarily by prolonging the ST segment
    • Torsades de pointes may occur

MANAGEMENT

  • Oral calcium supplementation:
  • Calcium carbonate (Caltrate®) 600 mg elemental calcium per tab
  • 1–2 g/day in 2–3 divided doses (e.g., 1 tab BD or TDS)
  • Correct hypomagnesemia if present
  • Switch to IV calcium if
    • Patient is symptomatic
    • Unable to tolerate or absorb oral formulations

For Oral Administration

  • Calcium carbonate (Caltrate®) 1–2 g daily in 2–3 divided doses (1 tab BD or TDS)
  • Switch to IV if the patient cannot tolerate or absorb oral formulations → Refer to Severe and/or Symptomatic Hypocalcemia

Available Oral Formulations (MOH)

  • Caltrate® 600 mg elemental calcium per tab
  • CaltrateD® 600 mg elemental calcium + 200 IU vitamin D per tab
  • Calsyr® syrup 5 mL contains 1.435 g calcium glubionate and 0.295 g calcium lactobionate
  • Calcium carbonate 20% syrup 20 mEq calcium per 5 mL (verify with pharmacy)

SEVERE and/or SYMPTOMATIC HYPOCALCEMIA

  • Symptoms present e.g., tetany, seizures, prolonged QT
  • Adjusted calcium < 2.0 mmol/L

MANAGEMENT

  • Continuous cardiac monitoring is essential
  • IV Calcium Replacement
  • Calcium gluconate:
    • 1–2 g (10–20 mL of 10%) diluted in 50 mL D5W or NS
    • Infuse over 10–20 minutes
    • May repeat after 10–60 minutes if symptoms persist
  • If unavailable: Calcium chloride
    • 1 g in 100 mL D5W or NS
    • Administer via central or large vein over 10–20 minutes
    • Repeat if symptoms persist
  • If persistent hypocalcemia is anticipated e.g., due to hypoparathyroidism or pancreatitis:
    • Continue with maintenance IV infusion
    • Call for senior help or endocrine input

Available IV Formulations (MOH)

  • Calcium gluconate 10%: 1 vial = 10 mL = 1 g = 90 mg elemental calcium
  • Calcium chloride 10%: 1 vial = 10 mL = 1 g = 270 mg elemental calcium

HYPERCALCEMIA

  • Mild: Adjusted calcium 2.6–3.0 mmol/L
  • Moderate: 3.0–3.5 mmol/L
  • Severe: >3.5 mmol/L

Clinical Features

  • Renal: Nephrolithiasis, polyuria.
  • Musculoskeletal: Bone pain, arthralgia.
  • GI: Abdominal pain, nausea, vomiting.
  • Neuropsychiatric: Confusion, mood changes, depression.

Investigations

  • Serum PTH, CBC, alkaline phosphatase & VBG
  • ECG
    • QT interval shortening
    • In severe cases: J wave, bradycardia, arrhythmias

Always call for senior help before initiating treatment

MANAGEMENT

  • IV fluid resuscitation:
    • NS 1–2 L bolus
    • Continue at 200–250 mL/hr
    • Adjust to maintain urine output 100–150 mL/hr
  • Loop diuretics (e.g., furosemide):
    • Only if signs of fluid overload or renal impairment

ESCALATION

  • Monitor serum calcium closely after treatment starts
  • Frequently reassess urine output and volume status
  • Escalate if calcium remains high despite initial management
MOC