Chapter 69: Disorders of Calcium and Phosphorus Homeostasis

Update Summary

July 10, 2023

The following sections were updated:

• Acute treatment of hypocalcemia: Updated elemental calcium description to include mg and mEq

• Pharmacologic therapy of hypercalcemia: Clarified availability of calcitonin

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 corticosteroids, depending on the etiology and acuity of the hypercalcemia.

• Hypocalcemia is typically associated with an insidious onset; however, some medications 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 intravenous (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 the “Clinical Presentation: Hypercalcemia” section)

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

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

  • 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 69-1)

• Acuity of symptoms and urgency for treatment (see Fig. 69-2)

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

• Kidney function (eg, serum creatinine, 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 69-2)

• Monitoring parameters include efficacy (eg, reduction in serum calcium, resolution of symptoms), safety (adverse medication reactions), and timeframe (see Table 69-2)

• Patient education (eg, purpose of treatment, medication 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 medication reactions

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

BEYOND THE BOOK

Watch the video entitled “Skeletal Endocrine Control” in Khan Academy by Tracy ...