What is the initial treatment approach for a dialysis patient with hypercalcemia and a Parathyroid Hormone (PTH) level of 136 pg/mL?

Management of Hypercalcemia in Dialysis Patient with PTH of 136 pg/mL

For a dialysis patient with hypercalcemia and a PTH level of 136 pg/mL, the initial treatment approach should focus on decreasing or discontinuing active vitamin D therapy and potentially initiating calcimimetic therapy with cinacalcet.

Understanding the Clinical Scenario

This patient presents with:

• Hypercalcemia
• PTH level of 136 pg/mL
• End-stage renal disease on dialysis

The PTH level of 136 pg/mL is actually at the lower end of the target range for dialysis patients (150-300 pg/mL according to KDOQI guidelines 1), suggesting this is not a case of severe secondary hyperparathyroidism.

Treatment Algorithm

Step 1: Adjust or Discontinue Vitamin D Therapy

• Immediately reduce or discontinue active vitamin D sterols (calcitriol, alfacalcidol, paricalcitol, or doxercalciferol) if the patient is currently receiving them 1
• This is the first-line intervention as vitamin D therapy is a common cause of hypercalcemia in dialysis patients 1, 2

Step 2: Evaluate and Adjust Calcium-Based Phosphate Binders

• Consider reducing or temporarily discontinuing calcium-based phosphate binders 1
• Switch to non-calcium-based phosphate binders if needed (sevelamer or lanthanum) 3

Step 3: Consider Calcimimetic Therapy

• If hypercalcemia persists, initiate cinacalcet at 30 mg once daily 4
• Cinacalcet directly inhibits PTH secretion by activating calcium-sensing receptors in the parathyroid glands 5
• Monitor serum calcium within 1 week after initiation 4
• Titrate dose no more frequently than every 2-4 weeks through sequential doses of 30,60,90,120, and 180 mg once daily 4

Step 4: Adjust Dialysate Calcium

• Consider using a lower calcium dialysate (2.5 mEq/L) if currently using a higher concentration 2
• Note that reducing dialysate calcium from 1.25 to 1.0 mmol/L alone may not be sufficient to control hypercalcemia 2

Monitoring Parameters

• Serum calcium and phosphorus: Check within 1 week after any medication adjustment 4
• PTH levels: Monitor monthly for at least 3 months and then every 3 months once target levels are achieved 1
• Target PTH range for dialysis patients: 150-300 pg/mL 1 or 150-600 pg/mL according to more recent guidelines 1

Special Considerations

Low PTH Level

• The PTH level of 136 pg/mL is slightly below the recommended target range for dialysis patients
• This suggests the patient may have adynamic bone disease, which can contribute to hypercalcemia due to decreased bone buffering capacity for calcium 2
• Avoid further suppression of PTH with vitamin D therapy 1

Cinacalcet Safety

• Ensure serum calcium is not below the lower limit of normal before initiating cinacalcet 4
• Monitor for symptoms of hypocalcemia (paresthesias, myalgias, muscle spasms, tetany) 4
• Cinacalcet can be used alone or in combination with vitamin D sterols and/or phosphate binders 4

Pitfalls to Avoid

1. Overtreatment of secondary hyperparathyroidism: This patient's PTH is already at the lower end of the target range, so aggressive PTH-lowering therapy should be avoided 1

2. Ignoring calcium intake from other sources: Evaluate dietary calcium intake and calcium supplementation 3

3. Failure to consider other causes of hypercalcemia: While secondary or tertiary hyperparathyroidism is common in dialysis patients, consider other causes such as malignancy, granulomatous diseases, or medications 6

4. Inadequate monitoring: Regular monitoring of calcium, phosphorus, and PTH is essential to prevent complications 1

By following this approach, hypercalcemia can be effectively managed while maintaining appropriate PTH levels for bone health in this dialysis patient.