According to KDIGO guidelines, what intact parathyroid hormone (iPTH) target range should be maintained for each estimated glomerular filtration rate (eGFR) stage?

KDIGO PTH Target Ranges by GFR Stage

The 2017 KDIGO guidelines do NOT provide specific intact PTH target ranges for CKD stages 3-5 (non-dialysis), but recommend maintaining iPTH between approximately 2 to 9 times the upper limit of normal (roughly 130-585 pg/mL for most assays) only for dialysis patients (CKD G5D). 1

PTH Management by CKD Stage

CKD Stage 3 (GFR 30-59 mL/min/1.73 m²)

• Begin monitoring iPTH when GFR falls below 60 mL/min/1.73 m² 1
• No specific target range is provided by KDIGO for stage 3 CKD 1
• The older 2003 K/DOQI guidelines suggested iPTH levels between 35-70 pg/mL for stage 3, but these specific targets were abandoned in the 2017 KDIGO update 1, 2
• Focus on trend monitoring rather than absolute targets, with treatment decisions based on progressive rises or biochemical abnormalities 1

CKD Stage 4 (GFR 15-29 mL/min/1.73 m²)

• Continue monitoring iPTH regularly 1
• No specific target range provided by KDIGO 1
• The older K/DOQI suggested 70-110 pg/mL for stage 4, but this was not retained in 2017 guidelines 1
• Treatment decisions should be based on trends and associated mineral abnormalities rather than single values 1

CKD Stage 5 Non-Dialysis (GFR <15 mL/min/1.73 m²)

• Monitor iPTH but no specific target range established 1
• Avoid letting iPTH fall below 2 times the upper limit of normal (approximately 130 pg/mL) if on PTH-lowering therapy 1

CKD Stage 5D (Dialysis)

• Target iPTH: 2 to 9 times the upper limit of normal for the assay 1, 2
• For most intact PTH assays with upper limit of normal at 65 pg/mL, this translates to approximately 130-585 pg/mL 2
• If iPTH falls below 2 times upper normal limit, reduce or stop calcitriol, vitamin D analogs, and/or calcimimetics (Grade 2C recommendation) 1
• Marked changes in PTH in either direction within this range should prompt therapy adjustment to prevent progression outside the target range 2

Key Algorithmic Approach to PTH Management

Step 1: Identify CKD Stage

• Use eGFR to determine stage (G3a, G3b, G4, G5, or G5D) 1

Step 2: Initiate Monitoring

• Begin iPTH monitoring when GFR <60 mL/min/1.73 m² 1
• Frequency not specified but should increase as CKD progresses 1

Step 3: Interpret Results by Context

• For G3-G5 (non-dialysis): No specific targets; monitor trends and associated calcium/phosphorus abnormalities 1
• For G5D (dialysis): Apply the 2-9× upper normal limit target 1, 2

Step 4: Treatment Thresholds

• Upper threshold concern: Progressive rises warrant intervention even if below 9× upper limit 2
• Lower threshold concern: iPTH <2× upper limit requires reduction/cessation of PTH-lowering agents 1

Critical Pitfalls to Avoid

Do not apply dialysis PTH targets to non-dialysis CKD patients - The 2-9× range is specific to G5D only 1, 2

Do not rely on single PTH values for treatment decisions in stages 3-5 non-dialysis - KDIGO emphasizes trends over absolute numbers for these stages 1

Recognize assay variability - Intact PTH assays detect non-(1-84) PTH fragments that accumulate as GFR declines, comprising up to 50% of measured "intact PTH" in dialysis patients 3. This means the biologically active PTH(1-84) may be lower than the measured value 3

Adjust therapy when iPTH drops too low - Even in dialysis patients, oversuppression (iPTH <2× upper normal) increases risk of adynamic bone disease and should prompt medication reduction 1

Rationale for Guideline Evolution

The 2017 KDIGO guidelines deliberately moved away from specific PTH targets for non-dialysis CKD stages because:

• Lack of evidence linking specific PTH levels to patient-centered outcomes (mortality, fractures, cardiovascular events) in stages 3-5 1
• Recognition that PTH assays measure heterogeneous molecular forms with varying biological activity 3
• Emphasis shifted toward managing trends and associated biochemical abnormalities rather than treating isolated PTH elevations 1

The dialysis population retained targets because bone biopsy data demonstrated that iPTH levels 2-9× upper normal best predicted appropriate bone turnover in this specific population 1, 2