What is the management of secondary hyperparathyroidism?

Management of Secondary Hyperparathyroidism

The management of secondary hyperparathyroidism (SHPT) in chronic kidney disease (CKD) patients on dialysis should begin with cinacalcet at 30 mg once daily, combined with vitamin D sterols and phosphate binders, with dose titration every 2-4 weeks based on iPTH levels. 1

Initial Assessment and Targets

• Monitor key laboratory parameters:
  • Serum calcium and phosphorus (within 1 week of treatment initiation)
  • Intact parathyroid hormone (iPTH) (1-4 weeks after treatment initiation)
  • Target iPTH levels: 150-300 pg/mL 1

Treatment Algorithm

First-Line Therapy

1. Phosphate Control

   • Dietary phosphorus restriction
   • Phosphate binders (preferably non-calcium containing to avoid hypercalcemia)
   • Monitor serum phosphorus levels regularly

2. Vitamin D Therapy

   • Active vitamin D sterols (calcitriol or vitamin D analogs)
   • Dosage should be adjusted according to severity of SHPT 2
   • For severe SHPT (iPTH >500-600 pg/mL), higher doses may be required
   • For very severe SHPT (iPTH >1,000 pg/mL), treatment may need to continue for 12-24 weeks 2

3. Calcimimetics

   • Start cinacalcet at 30 mg once daily with food 1
   • Titrate dose every 2-4 weeks through sequential doses of 30,60,90,120, and 180 mg once daily
   • Monitor serum calcium closely during titration
   • iPTH levels should be assessed no earlier than 12 hours after dosing 1

Monitoring and Dose Adjustments

• During dose titration, monitor serum calcium frequently

• If calcium decreases below normal range:

  • Provide supplemental calcium
  • Increase dose of calcium-based phosphate binder
  • Increase dose of vitamin D sterols
  • Consider temporarily withholding cinacalcet 1

• Once maintenance dose is established:

  • Measure serum calcium approximately monthly 1
  • If calcium falls below 8.4 mg/dL but remains above 7.5 mg/dL, adjust calcium-containing phosphate binders and/or vitamin D sterols
  • If calcium falls below 7.5 mg/dL, withhold cinacalcet until levels reach 8 mg/dL 1

Special Considerations

Severe and Refractory SHPT

For patients with persistent iPTH >800 pg/mL for >6 months despite exhaustive medical interventions, consider parathyroidectomy, especially with:

• Persistent hypercalcemia or hyperphosphatemia
• Tissue or vascular calcification
• Calciphylaxis
• Worsening osteodystrophy 3

Parathyroidectomy has been associated with 15%-57% greater survival in dialysis patients and improvements in mineral metabolism and quality of life 3.

Route of Administration for Vitamin D

The meta-analysis of trials comparing intermittent intravenous calcitriol with oral calcitriol indicated that intravenous therapy was more effective for suppression of intact PTH levels 2.

Pitfalls and Caveats

1. Hypercalcemia Risk: A major side effect of vitamin D treatment is increased intestinal absorption of calcium and phosphorus, which can produce hypercalcemia 2. Monitor calcium levels closely.

2. Cinacalcet Administration: Cinacalcet should always be taken with food and administered whole, never chewed, crushed, or divided 1.

3. Limitations of Cinacalcet: Not indicated for CKD patients who are not on dialysis due to increased risk of hypocalcemia 1.

4. Post-Parathyroidectomy Challenges: Hungry bone syndrome occurs in approximately 25% of dialysis patients after parathyroidectomy, requiring high doses of oral and intravenous calcium along with calcitriol supplementation 3.

5. Parathyroidectomy Considerations: Total parathyroidectomy with autotransplantation carries higher risk of permanent hypocalcemia, while subtotal parathyroidectomy has higher risk of SHPT recurrence 3.

By following this structured approach to SHPT management, focusing on controlling phosphate levels, administering appropriate vitamin D therapy, and using calcimimetics when indicated, clinicians can effectively manage this common complication of CKD while minimizing associated morbidity and mortality.