What treatment is recommended for an adult patient with a vitamin D level of 386 nmol/L and no underlying medical conditions?

Vitamin D Level of 386 nmol/L Requires Immediate Discontinuation

Stop all vitamin D supplementation immediately—a level of 386 nmol/L (approximately 154 ng/mL) exceeds the upper safety limit of 100 ng/mL and places the patient at significant risk for vitamin D toxicity. 1, 2

Understanding the Severity

• Your vitamin D level of 386 nmol/L converts to approximately 154 ng/mL, which is well above the established upper safety limit of 100 ng/mL (250 nmol/L) 1, 2
• Vitamin D toxicity typically occurs at 25(OH)D levels >150 ng/mL (>375 nmol/L), with acute toxicity associated with levels >200 ng/mL (>500 nmol/L) 2
• At this level, you are in the toxicity range where hypercalcemia and other serious complications can occur 2, 3

Immediate Actions Required

1. Discontinue All Vitamin D Supplementation

• Stop taking any vitamin D supplements immediately—this includes multivitamins containing vitamin D, prescription vitamin D, and over-the-counter preparations 2, 3
• The effects of administered vitamin D can persist for 2 or more months after cessation of treatment due to storage in adipose tissue 3

2. Urgent Laboratory Monitoring

• Check serum calcium levels immediately to assess for hypercalcemia, as this is the primary mechanism of vitamin D toxicity 2, 3
• Obtain serum phosphorus, parathyroid hormone (PTH), and renal function tests (creatinine, BUN) 2, 3
• Hypercalcemia caused by excess vitamin D occurs when 25(OH)D levels exceed 100 ng/mL, and you are currently at 154 ng/mL 2

3. Monitor for Toxicity Symptoms

• Watch for hypercalcemia symptoms including fatigue, weakness, nausea, vomiting, constipation, altered mental status, polyuria (excessive urination), and polydipsia (excessive thirst) 2
• Neurological symptoms can include irritability, confusion, and in severe cases, encephalopathy or coma 2
• Renal symptoms include polyuria and polydipsia due to hypercalcemia-induced nephrogenic diabetes insipidus 2

Treatment Protocol for Vitamin D Toxicity

If Hypercalcemia is Present (Calcium >10.2 mg/dL or 2.54 mmol/L)

• Immediate hydration with intravenous saline to increase urinary calcium excretion 2, 3
• Loop diuretics (furosemide or ethacrynic acid) may be given with saline infusion to further increase renal calcium excretion 3
• Glucocorticoids can be administered to reduce intestinal calcium absorption 3
• For severe hypercalcemia (calcium >14 mg/dL), additional measures include calcitonin, bisphosphonates, or dialysis 3

If Calcium is Normal

• Adopt a low-calcium diet temporarily (avoid dairy products, calcium-fortified foods, and calcium supplements) 3
• Increase fluid intake generously to promote renal excretion 3
• Avoid sun exposure during the recovery period, as UV radiation can further increase vitamin D levels 4

Follow-Up Monitoring Schedule

• Recheck serum calcium and 25(OH)D levels in 4-6 weeks to ensure levels are declining 2
• Continue monitoring calcium every 4-6 weeks until vitamin D levels fall below 100 ng/mL 2
• Monitor renal function (creatinine) to detect any kidney damage from hypercalciuria or nephrocalcinosis 3
• Once levels normalize (below 100 ng/mL), recheck every 3 months until stable in the optimal range of 30-80 ng/mL 1, 2

Expected Recovery Timeline

• Vitamin D has a long half-life and is stored in adipose tissue, so levels will decline slowly over 2-3 months even after complete cessation 3
• With appropriate therapy and no permanent organ damage, recovery is the usual outcome 3
• Deaths via renal or cardiovascular failure have been reported in cases of severe, untreated vitamin D toxicity 3

Critical Pitfalls to Avoid

• Do not resume any vitamin D supplementation until levels fall below 80 ng/mL and are discussed with your physician 1, 2
• Do not ignore symptoms—seek immediate medical attention if you develop confusion, severe nausea/vomiting, or decreased urine output 2, 3
• Do not take calcium supplements during this period, as they will worsen hypercalcemia if present 3
• Be aware that widespread calcification of soft tissues (heart, blood vessels, kidneys, lungs) can occur with prolonged toxicity 3

Investigation of the Cause

• Determine the source of excessive vitamin D intake—review all supplements, medications, and fortified foods 2
• Hypercalcemia caused by excess vitamin D in generally healthy adults has been observed only if daily intake was >100,000 IU or if 25(OH)D levels exceeded 100 ng/mL 2
• Consider whether you were taking high-dose prescription vitamin D (50,000 IU weekly or more frequently) without appropriate monitoring 1
• Rule out manufacturing errors in supplements or accidental overdosing 2

When Vitamin D Can Be Safely Resumed

• Only after levels fall below 80 ng/mL and with physician guidance 1, 2
• If supplementation is eventually needed, use no more than 2,000 IU daily for maintenance, as this dose is safe and effective for preventing deficiency 5, 6
• Daily doses up to 4,000 IU are generally considered safe for adults, but given your history of toxicity, lower doses are prudent 1, 2
• Never exceed 4,000 IU daily without specific medical indication and close monitoring 1, 2