Diagnosis and Management of Primary Hyperparathyroidism in Patients with Chronic Kidney Disease

Initial Laboratory Evaluation

The American College of Physicians recommends serum intact parathyroid hormone (iPTH), calcium, phosphorus, and 25-hydroxy vitamin D levels as essential initial laboratory tests to establish diagnosis and guide management of primary hyperparathyroidism in patients with chronic kidney disease (CKD) 1, 2
Serum calcium levels are crucial to assess for hypercalcemia, which is characteristic of primary hyperparathyroidism, according to the Endocrine Society 1, 2
Serum phosphorus levels are often low in primary hyperparathyroidism, as stated by the National Kidney Foundation 3
The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend assessing serum alkaline phosphatase (ALP) to evaluate bone turnover in patients with CKD 4, 3
The American Society of Nephrology suggests measuring 25-hydroxy vitamin D levels to rule out vitamin D deficiency, which can affect PTH levels in patients with CKD 2, 5
Blood urea nitrogen (BUN)/creatinine and estimated glomerular filtration rate (eGFR) are necessary to assess kidney function and determine CKD stage, as recommended by the National Institute of Diabetes and Digestive and Kidney Diseases 4

The Endocrine Society notes that PTH interpretation is challenging in CKD due to the accumulation of C-terminal PTH fragments with declining kidney function 2, 7
Second-generation PTH assays may overestimate PTH levels in CKD patients, according to the American Journal of Kidney Diseases 2, 7
The "gray zone" for PTH interpretation in CKD stage 5D is approximately 2-9 times the upper limit of normal, as stated by the Kidney International journal 8
The National Kidney Foundation recommends considering the patient's vitamin D status, BMI, race, and age when interpreting PTH values 2, 7

Secondary hyperparathyroidism due to CKD should be considered as a differential diagnosis, according to the Endocrine Reviews journal 7, 5
Tertiary hyperparathyroidism, characterized by autonomous parathyroid function after longstanding secondary hyperparathyroidism, is another possible diagnosis, as stated by the American Journal of Kidney Diseases 5
Bone disease related to CKD-mineral and bone disorder (CKD-MBD) should also be considered, according to the Kidney International journal 8, 5

Regular monitoring of iPTH, calcium, phosphorus, and ALP every 1-12 months is recommended, depending on CKD stage and clinical status, by the Nature Reviews Nephrology journal 3
Monitoring for progressive renal insufficiency and referring to nephrology if worsening is necessary, as stated by The Journal of Urology 4

Failing to consider normocalcemic primary hyperparathyroidism, which can still cause complications, is a common pitfall, according to the Endocrine Reviews journal 2, 7
Not accounting for the effect of CKD on PTH metabolism and interpretation is another pitfall to avoid, as recommended by the Endocrine Society 2, 7