Hypoparathyroidism medical therapy

Pharmacologic medical therapies for hypoparathyroidism include calcium and Vitamin D3 supplementation. Severe hypocalcemia, a potentially life-threatening condition, is treated as soon as possible with intravenous calcium (e.g. as calcium gluconate). Generally, a central venous catheter is recommended, as the calcium can irritate peripheral veins and cause phlebitis. Natpara (rhPTH) is a synthetic recombinant human parathyroid hormone approved by U.S. FDA in 2015 for treatment of hypoparathyroidism.

• Pharmacologic medical therapies for hypoparathyroidism include calcium and Vitamin D3 supplementation.^[1]
• Severe hypocalcemia, a potentially life-threatening condition, is treated as soon as possible with intravenous calcium (e.g. as calcium gluconate).
• Generally, a central venous catheter is recommended, as the calcium can irritate peripheral veins and cause phlebitis.

Management guidelines for hypoparathyroidism are as follows:

• 1 Management of Acute hypocalcemia

  Note(1): IV calcium used for marked hypocalcemia (<7.0 mg/dL), hypocalcemia associated with signs and symptoms, and if patients unable to take or absorb oral calcium supplements.

  • 1.1 Intravenous calcium supplementation

    • Preferred regimen (1): Calcium gluconate 1 to 2 g in 50 mL of 5% dextrose over 10-20 minutes initially followed by maintenance by 50 – 100 mg/hour.

    Note(1): 10% calcium gluconate is used which contains 90 mg of elemental calcium per 10 mL.

    Note(2): 1 mg/mL solution of elemental calcium is prepared as follows: Add 11 g of calcium gluconate (110 mL ) to 890 mL normal saline or 5% dextrose water making a final volume of 1000 mL. 11 g of calcium gluconate contains 990 mg of elemental calcium.

    Note(3): Rapid infusion of calcium gluconate should not be used as it carries serious risk of cardiac dysfunction, including systolic arrest.

  • 1.2 Parenteral vitamin D therapy

    • Preferred regimen (1): Calcitriol 0.25 to 0.5 μg q12h

  • 1.3 Intravenous Magnesium supplementation (in case of hypomagnesia)

    • Preferred regimen (1): Magnesium sulfate 2g (16mEq) as 10% solution, infused over 10 -20 minutes initially, followed by 1g (8 mEq) in 100 mL infused over an hour.

• 2 Conventional therapy for hypoparathyroidism
  • 2.1 Oral calcium

    • Preferred regimen (1): Calcium carbonate (40% elemental calcium) (better absorption with meals)
    • Alternative regimen (1): Calcium citrate (21% elemental calcium) (more effective in patients with achlorhydria and proton pump inhibitors use, worsening constipation)

  • 2.2 Vitamin D supplementation

    • Preferred regimen (1): Calcitriol 0.25 to 2 μg q24h (>.75 μg administered in divided doses)
    • Preferred regimen (2): Cholecalciferol (parent vitamin D3)
    • Preferred regimen (3): Ergocalciferol (parent vitamin D2)
    • Alternative regimen (1): 1α-Hydroxyvitamin D (alfacalcidol) (used outside the United States)
    • Alternative regimen (2): Dihydrotachysterol (used outside the United States)

    Note(1): Serum calcium (corrected for albumin), phosphorus, and creatinine concentrations should be measured weekly to monthly during dose adjustments, and twice annually once a stable regimen has been reached.

    Note(2): 24 Hour urinary calcium and creatinine should be considered during dose adjustments and should be measured twice annually on a stable regimen to evaluate for renal toxicity.

• 3 Adjunctive Treatments
  • 3.1 Diuretics
    • 3.1.1 Thiazides
      • Preferred regimen (1): Hydrochlorothiazide 25–50 mg q12h (minimum 25 mg to maximum 100 mg)
      • Alternative regimen (1): Chlorthalidone

      Note(1): Thiazide diuretics are not advised in congenital hypoparathyroidism due to autoimmune polyendocrine syndrome type 1 in patients who have concurrent Addison’s disease or in autosomal dominant hypocalcemia.

    • 3.1.2 Potassium sparing diuretics
      • Alternative regimen (1): Amiloride 2.5 to 5 mg q12h
  • 3.2 Treatment of hyperphoshatemia

    • Preferred regimen (1): Low phosphate diet
    • Preferred regimen (2): Phosphate binders

  • 3.3 PTH replacement

    • Preferred regimen (1): Natpara (rhPTH) 50 μg SC q24h (concomitantly decrease the dose of active vitamin D by 50%)

    Note(1): Monitor serum calcium and albumin concentrations every 3–7 days after initiation of therapy and after each dose change.

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