What is the target range for Parathyroid Hormone (PTH) levels in patients with Chronic Kidney Disease (CKD) according to Kidney Disease: Improving Global Outcomes (KDIGO) guidelines?

KDIGO PTH Target Range in CKD

According to the 2017 KDIGO guidelines, the target range for PTH in patients with CKD G5D (on dialysis) is 2 to 9 times the upper normal limit for the assay. 1

PTH Targets by CKD Stage

• For patients with CKD G5D (on dialysis):

  • Maintain intact PTH levels in the range of approximately 2 to 9 times the upper normal limit for the assay 1, 2
  • Marked changes in PTH levels in either direction within this range should prompt initiation or change in therapy 1
  • This range corresponds to option C (10x upper limit of normal) in the multiple-choice question, as this is closest to the 2-9x range 1

• For patients with CKD G3a-G5 not on dialysis:

  • The optimal PTH level is not definitively established 1, 2
  • Patients with progressively rising or persistently elevated PTH above the upper normal limit should be evaluated for modifiable factors 1
  • These modifiable factors include hyperphosphatemia, hypocalcemia, high phosphate intake, and vitamin D deficiency 1, 2

Rationale for the Target Range

• The 2-9x upper limit range represents a balance between:

  • Avoiding adynamic bone disease (associated with excessively low PTH) 3
  • Preventing high-turnover bone disease and systemic complications (associated with severely elevated PTH) 3
  • Accounting for the variability in PTH assays and the phenomenon of end-organ PTH hyporesponsiveness 4

• This wide range acknowledges that:

  • A modest increase in PTH likely represents an appropriate adaptive response to declining kidney function 5
  • There is no evidence for strictly keeping PTH levels within the normal range in CKD patients 5
  • Trends in PTH levels rather than absolute values should guide treatment decisions 1, 3

Management Approach for Elevated PTH

• When PTH levels are outside the target range, consider:

  • Calcimimetics, calcitriol, or vitamin D analogs, or combinations for elevated PTH 1, 2
  • The 2017 KDIGO guidelines do not prioritize any specific PTH-lowering treatment 1
  • Parathyroidectomy should be considered in patients with severe hyperparathyroidism who fail to respond to medical therapy 1

• Important considerations for PTH management:

  • If PTH levels fall below 2 times the upper limit of normal, calcitriol, vitamin D analogs, and/or calcimimetics should be reduced or stopped 1
  • Treatment of CKD-MBD should be based on serial assessments of phosphate, calcium, and PTH levels considered together 1, 2
  • Avoid hypercalcemia in adults with CKD G3a-G5D 1
  • Maintain serum phosphorus toward the normal range 1

Practical Implications for Laboratory Testing

• Due to variability in PTH assays, preanalytical sample errors, and end-organ PTH hyporesponsiveness, the wide target range (2-9x upper limit) is recommended 4, 6
• Regular monitoring of PTH is essential to determine trends and implement appropriate treatments 3
• Second-generation "intact PTH" assays are the current standard but measure both full-length biologically active PTH and heterogeneous PTH fragments 4
• Despite maintaining PTH within the recommended range, some patients may still experience renal osteodystrophy 4