What is the next step in treatment for a patient with Chronic Kidney Disease (CKD) not on dialysis, presenting with hypocalcemia, a Parathyroid Hormone (PTH) level of 90, and normal Vitamin D levels?

Treatment of Hypocalcemia in CKD Not on Dialysis with PTH 90 and Normal Vitamin D

Administer oral calcium supplementation to correct the hypocalcemia, as this is the primary modifiable factor driving the mildly elevated PTH in this clinical scenario. 1

Rationale for Calcium Supplementation

The 2017 KDIGO guidelines explicitly recommend that patients with CKD G3a-G5 not on dialysis who have PTH levels above the upper normal limit should first be evaluated for modifiable factors including hypocalcemia, hyperphosphatemia, high phosphate intake, and vitamin D deficiency. 1 Since vitamin D is already normal in this patient, the hypocalcemia becomes the primary correctable abnormality.

• Calcium supplements are specifically recommended to correct hypocalcemia in CKD patients with elevated PTH when vitamin D levels are adequate. 1
• The guideline states it is reasonable to correct these abnormalities with calcium supplements before considering more aggressive interventions. 1

Why NOT Active Vitamin D Therapy

Active vitamin D (calcitriol or analogs) should NOT be used routinely in this patient. 1

• The 2017 KDIGO update explicitly recommends against routine use of calcitriol and vitamin D analogs in CKD G3a-G5 not on dialysis (Grade 2C). 1
• These agents should be reserved only for patients with CKD G4-G5 with severe and progressive hyperparathyroidism (typically PTH >300-500 pg/mL). 1
• A PTH of 90 pg/mL represents only mild elevation and does not meet criteria for "severe and progressive" hyperparathyroidism. 1
• Recent RCTs (PRIMO and OPERA) showed that paricalcitol in CKD stage 3-4 patients did not improve cardiovascular outcomes and significantly increased hypercalcemia risk (22.6% vs 0.9%). 1

Why NOT Cinacalcet

Cinacalcet is contraindicated in this patient for two critical reasons:

• The FDA label explicitly states cinacalcet is not indicated for CKD patients not on dialysis due to increased risk of hypocalcemia. 2
• Cinacalcet treatment initiation is contraindicated when serum calcium is below the lower limit of normal, which applies to this patient with hypocalcemia. 2

Practical Implementation

Calcium supplementation approach:

• Calcium citrate may be preferred over calcium carbonate if malabsorption is suspected. 3
• Avoid administering calcium supplements with high-phosphate foods to optimize absorption. 3
• The goal is to normalize serum calcium, which should subsequently reduce PTH secretion through normal feedback mechanisms. 1

Monitoring Strategy

• Measure serum calcium and phosphorus every 3 months during calcium supplementation therapy. 4, 5
• Recheck PTH after correcting hypocalcemia (typically 1-3 months) to assess response. 1
• If PTH remains progressively rising or persistently elevated despite correction of hypocalcemia, then reassess for other modifiable factors including dietary phosphate intake. 1

Critical Pitfall to Avoid

The most common error is jumping to active vitamin D therapy (calcitriol/analogs) in CKD patients not on dialysis with mildly elevated PTH. 1 This approach:

• Increases hypercalcemia risk without proven benefit on patient-centered outcomes 1
• Should be reserved for severe, progressive hyperparathyroidism in advanced CKD (stages 4-5) 1
• Is not indicated when simple correction of hypocalcemia with calcium supplementation can address the underlying stimulus for PTH elevation 1