Recommended iPTH Level for Dialysis Patients
The target intact PTH (iPTH) level for dialysis patients should be maintained between 150-300 pg/mL (16.5-33.0 pmol/L), with treatment initiated when iPTH exceeds 300 pg/mL. 1
Target Range and Treatment Thresholds
For hemodialysis and peritoneal dialysis patients:
- Target range: 150-300 pg/mL (16.5-33.0 pmol/L) 1
- Treatment threshold: iPTH >300 pg/mL (33.0 pmol/L) requires active vitamin D sterol therapy 1
- Lower safety limit: iPTH <100 pg/mL (11.0 pmol/L) indicates adynamic bone disease risk 1, 2
The K/DOQI guidelines explicitly state that patients with iPTH >300 pg/mL should receive active vitamin D sterols (calcitriol, alfacalcidol, paricalcitol, or doxercalciferol) to reduce PTH to the 150-300 pg/mL target range. 1
Rationale for This Range
The 150-300 pg/mL target represents 2-4 times the upper limit of normal to account for PTH resistance in uremic patients. 3 This range balances two critical risks:
- iPTH <150 pg/mL: Associated with low-turnover/adynamic bone disease, which impairs the skeleton's ability to buffer calcium and phosphorus loads, leading to vascular calcification 1, 2
- iPTH >300 pg/mL: Associated with high-turnover bone disease (osteitis fibrosa) and progressive secondary hyperparathyroidism 1
Cardiovascular Disease Prevention
For cardiovascular disease prevention specifically, the target PTH should be 150-300 pg/mL. 1 This recommendation integrates bone disease management with cardiovascular risk reduction, as both excessively low and high PTH levels are associated with increased mortality and major adverse cardiac events. 4
Important Caveats and Clinical Nuances
The K/DOQI Target May Be Too Low
Critical limitation: Research demonstrates that 88% of patients achieving the K/DOQI target range (150-300 pg/mL) had low-turnover bone disease on biopsy. 5 This suggests the recommended range may be associated with oversuppression and adynamic bone disease in clinical practice. 5
Low PTH carries significant mortality risk: Patients with time-averaged iPTH <65 pg/mL have a 2-fold increased risk of overall mortality (HR=2.06) and 1.8-fold increased risk of major adverse cardiac and cerebrovascular events (HR=1.82) compared to those with iPTH 65-300 pg/mL. 4
Severity-Based Considerations
Disease severity affects treatment response: 6
- Mild disease (iPTH 300-500 pg/mL): 60% achieve target with treatment 7
- Moderate disease (iPTH 500-800 pg/mL): 41% achieve target 7
- Severe disease (iPTH >800 pg/mL): Only 11% achieve target; may require parathyroidectomy if iPTH persistently >800 pg/mL with refractory hypercalcemia/hyperphosphatemia 1, 7
Monitoring Protocol
When initiating or adjusting vitamin D therapy: 1, 2
- Calcium and phosphorus: Every 2 weeks for 1 month, then monthly 1, 2
- iPTH: Monthly for at least 3 months, then every 3 months once target achieved 1, 2, 8
Treatment must be held if: 2, 8
- Corrected calcium >9.5 mg/dL 2, 8
- Phosphorus >4.6 mg/dL 2, 8
- iPTH falls below 150 pg/mL (resume at 50% dose when iPTH rises above target) 2, 8
Practical Algorithm for PTH Management
Step 1 - Assess iPTH level:
- <100 pg/mL: Hold/reduce vitamin D and calcium-based binders; allow PTH to rise 1, 2
- 100-150 pg/mL: Monitor closely; consider reducing vitamin D dose 2
- 150-300 pg/mL: Target range; maintain current therapy 1
- 300-800 pg/mL: Initiate/increase vitamin D sterols 1
- >800 pg/mL: Consider parathyroidectomy if refractory to medical therapy 1
Step 2 - Verify calcium and phosphorus are controlled before treating elevated PTH:
Step 3 - Select appropriate vitamin D sterol:
- Hemodialysis: Intravenous calcitriol preferred (more effective than oral) 1
- Peritoneal dialysis: Oral calcitriol 0.5-1.0 μg or doxercalciferol 2.5-5.0 μg, 2-3 times weekly 1, 8
- If hypercalcemia/hyperphosphatemia present: Consider paricalcitol or doxercalciferol (less calcemic) 1
Common Pitfalls to Avoid
Oversuppression is more dangerous than previously recognized. The evidence shows that achieving the lower end of the K/DOQI target range frequently results in adynamic bone disease. 5 In clinical practice, aim for the middle-to-upper portion of the 150-300 pg/mL range rather than aggressively targeting the lower end. 5, 4
Do not treat elevated PTH when calcium or phosphorus are uncontrolled. This leads to dangerous calcium-phosphorus product elevation and vascular calcification. 2, 8 Always optimize phosphate binders and dietary restriction first. 1
Recognize that iPTH alone may not accurately reflect bone turnover status. Bone biopsy remains the gold standard, though impractical for routine use. 1, 5 When iPTH is in the target range but clinical suspicion exists for adynamic bone (low alkaline phosphatase, hypercalcemia), consider holding vitamin D therapy. 1