What is the parathyroid hormone (PTH) cut off for patients with secondary hyperparathyroidism on dialysis?

PTH Cut-off for Secondary Hyperparathyroidism in Dialysis Patients

For patients with secondary hyperparathyroidism on dialysis, a PTH level greater than 800 pg/mL is the most widely accepted cut-off for considering surgical intervention when medical therapy has failed. 1

Evidence-Based PTH Thresholds

• Multiple studies use PTH > 800 pg/mL as the threshold for surgical intervention in dialysis patients with secondary hyperparathyroidism, especially when accompanied by symptoms and resistance to medical therapy 1

• Some centers use a more stringent criterion of PTH levels persistently greater than ten times the normal upper limit (approximately 650-700 pg/mL) as an indication for parathyroidectomy 1

• For medical management with cinacalcet, the target iPTH range is 150-300 pg/mL (16.5-33.0 pmol/L) according to clinical guidelines 2, 3

Surgical Intervention Criteria

• Surgical parathyroidectomy should be considered when PTH levels exceed 800 pg/mL along with one or more of the following conditions:

  • Persistent hypercalcemia (>10.2 mg/dL) 1
  • Elevated phosphorus (>5.5 mg/dL) 1
  • Calcium-phosphorus product >70 mg²/dL² 1
  • Worsening symptoms resistant to conventional medical therapy (including calcimimetics) 1
  • Evidence of progressive bone disease, calciphylaxis, or extraskeletal calcifications 1

• The most recent high-quality randomized controlled trial (Schlosser et al. 2016) used PTH levels 10-fold above the upper normal value as the threshold for surgical intervention in dialysis patients 1

Medical Management Thresholds

• For patients on dialysis, cinacalcet should be initiated at 30 mg once daily when PTH levels exceed 300 pg/mL despite standard therapy 3

• Cinacalcet dosing should be titrated every 2-4 weeks to achieve target iPTH levels of 150-300 pg/mL 3

• Serum iPTH levels should be assessed no earlier than 12 hours after dosing with cinacalcet 3

Monitoring Recommendations

• After initiating cinacalcet, serum calcium and phosphorus should be measured within 1 week, and iPTH should be measured 1-4 weeks after initiation or dose adjustment 3

• Once maintenance dose is established, serum calcium should be monitored approximately monthly for patients with secondary hyperparathyroidism on dialysis 3

• If serum calcium falls below 8.4 mg/dL but remains above 7.5 mg/dL, calcium-containing phosphate binders and/or vitamin D sterols can be used to raise serum calcium 3

Clinical Pitfalls and Caveats

• PTH assay variability can affect interpretation of results, so consistent use of the same assay is recommended 4

• Some patients may exhibit bone disease with only moderately elevated PTH levels, highlighting the importance of clinical symptoms in decision-making 1

• Japanese studies have shown a more linear relationship between PTH and mortality, suggesting potential regional differences in optimal PTH targets 1

• Cinacalcet effectively reduces PTH levels but has not been shown to improve mortality outcomes, so surgical intervention may be preferable for severe, refractory cases 1, 5

• While parathyroidectomy is effective for lowering PTH, careful postoperative monitoring for hypocalcemia is essential 5