Chapter 67: Disorders of Calcium and Phosphorus Homeostasis

KEY CONCEPTS

• Severe acute hypercalcemia can result in cardiac arrhythmias, whereas chronic hypercalcemia can lead to calcium deposition in soft tissues including blood vessels and the kidney.

• The correction of hypercalcemia can include multiple pharmacotherapeutic modalities such as hydration, diuretics, bisphosphonates, and steroids, depending on the etiology and acuity of the hypercalcemia.

• Hypocalcemia is typically associated with an insidious onset; however, some drugs such as cinacalcet are associated with rapid decreases in serum calcium.

• Acute treatment of hypocalcemia requires calcium supplementation whereas chronic management may require other therapies such as vitamin D to maintain serum calcium concentrations.

• Hyperphosphatemia occurs most frequently in patients with chronic kidney disease (CKD).

• Treatment of nonemergent hyperphosphatemia includes the use of phosphate binders to decrease absorption of phosphorus from the gastrointestinal (GI) tract.

• Hypophosphatemia is a relatively common complication among critically ill patients.

• Treatment of acute hypophosphatemia usually requires IV phosphorus supplementation.

Patient Care Process for the Management of Hypercalcemia

Collect

• Patient characteristics (eg, age, race, sex)

• Patient history (past medical, family, social—dietary habits)

• Evaluate symptoms (see “Clinical Presentation: Hypercalcemia”)

• Current medications, including over-the-counter medications, herbal products, nutritional supplements

• Objective data (see “Clinical Presentation: Hypercalcemia”)

  • Blood pressure, heart rate, height, weight

  • Labs (serum calcium and albumin, ionized calcium when available)

  • Other diagnostic tests when indicated (eg, ECG)

Assess

• Plausible etiology for hypercalcemia (see Table 67-1)

• Acuity of symptoms and urgency for treatment (see Fig. 67-2)

• Current medications and dietary intake that may contribute to or worsen hypercalcemia

• Kidney function (eg, creatinine clearance)

• Serum calcium goal

Plan^*

• Pharmacotherapy based on etiology of hypercalcemia including specific dose, route of administration, frequency of administration, and anticipated duration of treatment (see Table 67-2)

• Monitoring parameters including efficacy (eg, reduction in serum calcium, resolution of symptoms), safety (medication-specific adverse effects), and time frame (see Table 67-2)

• Patient education (eg, purpose of treatment, drug therapy, expected time to reduce calcium, need for future medications)

Implement^*

• Provide patient education regarding all elements of treatment plan

• Schedule follow-up based on acuity and symptoms

Follow-up: Monitor and Evaluate

• Measure serum calcium to determine response

• Presence of adverse effects

• Consider alternative medication management if desired reduction in calcium is not achieved

Preclass Engaged Learning Activity

Visit the Kidney Disease: Improving Global Outcomes (KDIGO) website and review the updated guidelines for CKD-Mineral and Bone Disorder (CKD-MBD). View the CKD-MBD Visual Guidelines related to “Management of Phosphate & Calcium Levels.” Explore the treatment algorithm and the information provided within the decision tree. This website addresses the COLLECT, ASSESS, and PLAN steps of the Patient Care Process and is useful to enhance student understanding of management of calcium and phosphorus in patients with CKD.