What is the treatment for vitamin D toxicity?

Treatment of Vitamin D Toxicity

The primary treatment for vitamin D toxicity is immediate discontinuation of vitamin D supplementation combined with aggressive management of hypercalcemia through intravenous hydration with saline, loop diuretics, glucocorticoids, calcitonin, and bisphosphonates when calcium exceeds 14 mg/dL. 1, 2

Immediate Management Steps

Discontinue Vitamin D Exposure

• Stop all vitamin D supplementation immediately 2, 3
• Identify and remove all sources, including unexpected sources like contaminated supplements or manufacturing errors 3
• Recognize that effects may persist for months despite stopping the source, as vitamin D is stored in adipose tissue 2

Assess Severity of Hypercalcemia

• Emergency intervention is required when serum calcium exceeds 14 mg/dL (3.5 mmol/L) due to adverse effects on cardiac, central nervous system, renal, and gastrointestinal function 2
• Vitamin D toxicity typically occurs at 25(OH)D levels >150 ng/mL (>375 nmol/L), with levels >200 ng/mL (>500 nmol/L) associated with acute toxicity 1

Specific Treatment Interventions

First-Line Therapy

• Intravenous hydration with normal saline to promote calciuresis and restore intravascular volume 2, 3
• Loop diuretics (after adequate hydration) to enhance urinary calcium excretion 2
• Low calcium and phosphorus diet to minimize intestinal calcium absorption 2

Second-Line Therapy for Severe Cases

• Glucocorticoids to reduce intestinal calcium absorption and increase urinary calcium excretion 2
• Calcitonin for rapid reduction of serum calcium (though effect is transient) 2, 3
• Bisphosphonates (such as pamidronate) for sustained reduction in serum calcium by inhibiting bone resorption 3

Monitoring and Follow-Up

Laboratory Surveillance

• Monitor serum calcium, phosphorus, creatinine, and 25(OH)D levels serially 2, 3
• Expect prolonged recovery: normalization of calcium may occur within days to weeks, but 25(OH)D levels may take 6-18 months to normalize 3, 4
• Continue low-calcium diet and laboratory monitoring for months after initial presentation 3

Renal Function Assessment

• Acute kidney injury is common with vitamin D toxicity and requires monitoring of eGFR 3, 4
• Renal function may take approximately 6 months to normalize 4

Clinical Pitfalls to Avoid

Do not assume vitamin D supplements are always safe at "standard" doses - toxicity has occurred from manufacturing errors in products not claiming to contain vitamin D 3, and from overzealous correction of deficiency with mega-doses 5

Do not overlook non-traditional sources - contaminated creatine supplements, protein powders, and other natural health products can contain massive amounts of undeclared vitamin D (up to 425,000 IU per serving) 3

Do not expect rapid resolution - vitamin D's lipophilic nature means tissue stores will continue releasing the vitamin for months, requiring sustained dietary restriction and monitoring even after hypercalcemia resolves 2, 4

Diagnostic Confirmation

Typical laboratory findings in vitamin D toxicity include 2:

• Hypercalcemia
• Normal or elevated serum phosphorus
• Normal or low alkaline phosphatase
• Markedly elevated 25(OH)D (>150 ng/mL)
• Suppressed parathyroid hormone
• Elevated urine calcium/creatinine ratio