From the Guidelines
In patients with hyperparathyroidism of renal origin, it is crucial to monitor serum calcium, phosphorus, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, alkaline phosphatase, blood urea nitrogen (BUN), creatinine, and estimated glomerular filtration rate (eGFR) regularly, typically every 3-6 months, to guide treatment decisions and prevent complications such as renal osteodystrophy and vascular calcification. The most recent and highest quality study, 1, emphasizes the importance of monitoring these laboratory tests to assess the interplay among biochemical variables in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD). Key laboratory tests to monitor include:
- Serum calcium and phosphorus levels
- Intact parathyroid hormone (iPTH) levels
- 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels
- Alkaline phosphatase levels
- Blood urea nitrogen (BUN) and creatinine levels
- Estimated glomerular filtration rate (eGFR) A comprehensive metabolic panel should also be ordered to assess electrolyte balance, particularly potassium and bicarbonate levels, as noted in 1. Additionally, albumin levels are important to interpret calcium results correctly, as calcium binds to albumin in the blood, highlighting the need for regular monitoring of these parameters, as suggested in 1. The study 1 also recommends monitoring calcium, phosphorus, and iPTH levels at least every three months in patients with a GFR of 30 ml/min per 1.73 m2. Overall, regular monitoring of these laboratory tests is essential to guide treatment decisions and prevent complications in patients with hyperparathyroidism of renal origin, as supported by the studies 1.
From the FDA Drug Label
Serum calcium and serum phosphorus should be measured within 1 week and intact parathyroid hormone (iPTH) should be measured 1 to 4 weeks after initiation or dose adjustment of cinacalcet tablets During dose titration, serum calcium levels should be monitored frequently Serum iPTH levels should be assessed no earlier than 12 hours after dosing with cinacalcet tablets.
The important labs to check in a patient with hyperparathyroidism of renal origin are:
From the Research
Important Labs for Hyperparathyroidism of Renal Origin
To diagnose and manage hyperparathyroidism of renal origin, several laboratory tests are crucial. These include:
- Serum calcium levels: Hyperparathyroidism is characterized by elevated serum calcium levels, although in some cases, especially in renal hyperparathyroidism, serum calcium may be low or normal 3.
- Serum phosphorus levels: Phosphorus retention is a key factor in the development of secondary hyperparathyroidism in chronic kidney disease, leading to an increase in parathyroid hormone secretion 4, 3.
- Parathyroid hormone (PTH) levels: Elevated PTH levels are a hallmark of hyperparathyroidism. In renal hyperparathyroidism, PTH levels are often significantly elevated 4, 3.
- Vitamin D levels: Vitamin D deficiency is common in patients with chronic kidney disease and contributes to the development of secondary hyperparathyroidism. Measuring vitamin D levels is essential for guiding replacement therapy 4, 3.
- Renal function tests: Assessing renal function through tests such as serum creatinine and estimated glomerular filtration rate (eGFR) is critical in understanding the severity of kidney disease and its impact on mineral metabolism 4, 3.
Additional Considerations
In the evaluation of hyperparathyroidism of renal origin, it is also important to consider other factors that may influence mineral metabolism, such as: