Diagnosis and Management of Secondary Hyperparathyroidism

Initial Laboratory Assessment

The American College of Physicians recommends measuring intact PTH, serum calcium, serum phosphorus, and 25-hydroxyvitamin D in all patients with CKD and GFR <60 mL/min/1.73 m² to establish the diagnosis and guide treatment 1, 2
The Endocrine Society suggests using second-generation "intact PTH" assay, which is the standard in most laboratories and adequate for screening 3
Serum calcium (corrected for albumin) should be measured to identify hypocalcemia driving PTH elevation 1, 2
Serum phosphorus should be measured as hyperphosphatemia is a key driver of secondary hyperparathyroidism 1, 2
25-hydroxyvitamin D [25(OH)D] deficiency (<30 ng/mL) contributes to PTH elevation and requires repletion 2, 4
Alkaline phosphatase should be measured as elevated levels suggest high bone turnover 2

For CKD Stage 3 (GFR 30-59 mL/min/1.73 m²), measure calcium, phosphorus, and PTH annually 1, 2
For CKD Stage 4 (GFR 15-29 mL/min/1.73 m²), measure calcium and phosphorus every 3-6 months 1, 2
For CKD Stage 5 (GFR <15 mL/min/1.73 m² or on dialysis), measure calcium and phosphorus monthly initially, then every 1-3 months once stable 1, 2
The National Kidney Foundation recommends targeting PTH range of 150-300 pg/mL (not normal range) for CKD Stage 5 6, 2, 4

The American Journal of Kidney Diseases suggests evaluating for the three primary drivers of secondary hyperparathyroidism: hyperphosphatemia, hypocalcemia, and vitamin D deficiency 1, 2
Hyperphosphatemia is defined as serum phosphorus >4.6 mg/dL in CKD stages 3-4, or >5.5 mg/dL in stage 5 1, 2
Hypocalcemia is defined as corrected serum calcium <8.4 mg/dL 1, 2
Vitamin D deficiency is defined as 25(OH)D <30 ng/mL and requires repletion with ergocalciferol 50,000 IU monthly 2

The International Journal of Surgery recommends assessing for complications of uncontrolled secondary hyperparathyroidism, including bone disease markers and vascular calcification risk 2, 6, 4
Vascular calcification risk can be calculated using the calcium-phosphorus product (should be <55 mg²/dL²) 6, 4
Parathyroid imaging (ultrasound or sestamibi scan) is reserved for surgical planning in refractory cases, not for initial diagnosis 7, 8

The American Journal of Kidney Diseases recommends measuring calcium and phosphorus within 1 week of starting therapy, and PTH 1-4 weeks after initiation or dose adjustment 2, 8
During vitamin D sterol therapy, monitor calcium and phosphorus every 2 weeks for 1 month, then monthly 8
Monitor PTH monthly for at least 3 months, then every 3 months once target achieved 8
The National Kidney Foundation suggests never targeting "normal" PTH levels (<65 pg/mL) in dialysis patients, as this causes adynamic bone disease with increased fracture risk and loss of bone buffering capacity for calcium 6, 2, 4