What is the target Parathyroid Hormone (PTH) level in Chronic Kidney Disease (CKD) patients?

Target PTH Level in CKD Patients

The target intact PTH level for patients with CKD on dialysis (Stage 5D) should be maintained in the range of 150 to 300 pg/mL. 1

PTH Target Ranges by CKD Stage

• For patients with CKD Stage 5 on dialysis (CKD-5D), intact PTH levels should be maintained between 150-300 pg/mL to balance the risks of high-turnover and low-turnover bone disease 1
• PTH levels below 150 pg/mL in dialysis patients are associated with higher mortality rates and increased risk of adynamic bone disease 2
• PTH levels above 300 pg/mL in dialysis patients indicate high-turnover bone disease with a sensitivity of 93% and specificity of 77% 1
• For non-dialysis CKD patients (Stages 3-5), PTH targets should be progressively higher as kidney function declines, though specific targets are less well-defined 3

Diagnostic Value of PTH Measurements

• Intact PTH assays using a threshold of 150-200 pg/mL can detect high-turnover bone disorders with 93% sensitivity and 77% specificity 1
• Low-turnover bone disorders can be diagnosed using a PTH threshold of 60 pg/mL with 70% sensitivity and 87% specificity 1
• The relationship between PTH levels and bone turnover is not linear, as "intact PTH" assays measure both full-length biologically active PTH and heterogeneous PTH fragments 4
• Current guidelines recommend a wide target range to minimize the risk of developing adynamic bone disease while preventing severe hyperparathyroidism 3

Monitoring Recommendations

• For patients on dialysis initiating vitamin D sterol therapy, PTH should be measured monthly for at least 3 months and then every 3 months once target levels are achieved 1
• Increasing monitoring frequency from quarterly to monthly has been shown to significantly improve the percentage of patients reaching target PTH values 5
• PTH measurements should be interpreted as trends rather than isolated values due to assay variability and biological fluctuations 3
• Monitoring should begin when GFR falls below 60 mL/min/1.73 m² (CKD Stage 3) 1

Management Considerations

• When PTH levels exceed 300 pg/mL in dialysis patients, active vitamin D sterols should be initiated to reduce PTH to the target range 1
• Vitamin D receptor activator (VDRA) therapy is associated with improved survival in dialysis patients, even in those with low PTH levels (≤150 pg/mL) 2
• Intermittent intravenous administration of calcitriol is more effective than daily oral calcitriol in lowering serum PTH levels 1
• Treatment decisions should consider calcium and phosphorus levels alongside PTH, as hypercalcemia (>9.5 mg/dL) or hyperphosphatemia (>4.6 mg/dL) may necessitate adjustments in therapy 1

Common Pitfalls and Caveats

• Different PTH assays may yield varying results, making it essential to use the same assay consistently for monitoring individual patients 4
• Newer assays specific for 1-84 PTH (third-generation assays) may provide more accurate assessment of biologically active PTH but are not yet standard clinical tools 1, 4
• Relying solely on PTH without considering calcium and phosphorus levels can lead to suboptimal management of CKD-MBD 3
• Overcorrection of PTH to normal levels in advanced CKD may lead to adynamic bone disease and increased risk of vascular calcification 4

Based on the evidence provided, the answer to the multiple-choice question is c. 200 pg/mL, as this falls within the recommended target range of 150-300 pg/mL for dialysis patients and represents a midpoint value in this range.