Mineral and Bone Disorder Management

Introduction to Mineral and Bone Health

• The skeletal system regulates calcium homeostasis, phosphate homeostasis, and bone remodeling, as stated by the Endocrine Society and Blood Reviews 1, 2
• Parathyroid hormone (PTH) is a central regulator that acts on bone to release calcium into the bloodstream when serum calcium levels fall, according to the Endocrine Society 1
• Iron plays a critical role in bone formation through hydroxylase enzymes required for collagen I synthesis, as noted by the Blood Reviews 2
• Growth hormone influences bone development and iron metabolism, with implications for bone health, as reported by the Blood Reviews 2

Calcium Intake and Correction

• The American Academy of Family Physicians recommends that an 18-year-old female maintain a daily calcium intake of 1,300 mg/day to support bone health 3
• The normal reference range for ionized calcium is 1.1-1.3 mmol/L, which is pH-dependent, and a 0.1 unit increase in pH decreases ionized calcium concentration by approximately 0.05 mmol/L 4
• The following formulas can be used to correct total calcium for albumin:

Target Calcium and Phosphate Levels

• Target calcium levels in CKD patients should be between 8.4-9.5 mg/dL (2.1-2.37 mmol/L), and serum phosphate levels should be maintained between 2.7-4.6 mg/dl (0.87-1.49 mmol/l) for CKD stages 3-4 and between 3.5-5.5 mg/dl (1.13-1.78 mmol/l) for CKD stage 5, as recommended by the American Journal of Kidney Diseases 5
• Dietary phosphate restriction of 800-1000 mg/day (adjusted according to protein intake) is recommended for patients with elevated phosphate levels (>4.6 mg/dl for CKD stages 3-4, >5.5 mg/dl for CKD stage 5), as recommended by the American Journal of Kidney Diseases 5

Treatment of Hypocalcemia and Hyperparathyroidism

• For rapid correction in critical situations, give 10 mL of 10% calcium chloride (or 30 mL of 10% calcium gluconate) IV over 5-10 minutes 6
• For severe hypocalcemia, initiate calcium gluconate infusion at 1-2 mg elemental calcium per kg body weight per hour, adjusting the infusion rate to maintain ionized calcium within the normal range, and transition to oral calcium carbonate (1-2 g three times daily) and add calcitriol (up to 2 μg/day) when oral intake is possible, as recommended by the American Journal of Kidney Diseases 5
• Target iPTH levels in CKD stage 5 (dialysis) are 150-300 pg/mL, as recommended by the American Journal of Kidney Diseases 5
• Patients with severe hyperparathyroidism not responsive to medical therapy should be considered for parathyroidectomy, as recommended by the American Journal of Kidney Diseases 5

Monitoring and Prevention of Mineral and Bone Disorders

• Calcium levels and magnesium levels should be monitored, as magnesium deficiency can contribute to hypocalcemia, as recommended by the Genetics in Medicine guidelines 7
• Citrate accumulation is more likely in patients with shock with muscle hypoperfusion 8
• Use strict protocols for citrate administration during CRRT 8
• Consider CRRT without anticoagulation in patients at high bleeding risk 9
• The treatment for citrate toxicity requires immediate administration of calcium, preferably calcium chloride, to restore ionized calcium levels when hypocalcemia is detected during continuous renal replacement therapy or other procedures using citrate anticoagulation 6