As a typical adult without kidney disease, hypercalcemia, granulomatous disease, or sarcoidosis, my serum 25‑hydroxyvitamin D level is 28.2 ng/mL; how should I manage it?

Management of Vitamin D Level 28.2 ng/mL

You should supplement with 1,000–2,000 IU of cholecalciferol (vitamin D3) daily and recheck your level in 3 months, targeting at least 30 ng/mL for optimal bone health and fracture prevention. 1, 2

Understanding Your Current Status

Your level of 28.2 ng/mL falls into the "insufficiency" range—not frank deficiency, but suboptimal for preventing secondary hyperparathyroidism, maintaining bone mineral density, and reducing fracture risk. 3, 1, 2

• Levels below 30 ng/mL are associated with elevated parathyroid hormone (PTH), lower bone mineral density, and increased hip fracture risk compared to age-matched controls. 3, 2
• Anti-fracture efficacy begins at 30 ng/mL, while anti-fall efficacy starts at 24 ng/mL—your current level provides some fall protection but insufficient fracture prevention. 1, 2
• The target range for optimal health is 30–44 ng/mL, well below the upper safety limit of 100 ng/mL. 1, 2

Recommended Treatment Protocol

Initial Supplementation Approach

For your level of insufficiency (not deficiency), daily supplementation is preferred over high-dose weekly loading:

• Add 1,000 IU of vitamin D3 daily to your current intake (from diet and sun exposure), which will raise your level by approximately 10 ng/mL over 3 months. 1
• Alternatively, 2,000 IU daily is reasonable if you want more aggressive correction, particularly if you are over 65 years old or have risk factors for deficiency. 1, 2
• Cholecalciferol (D3) is strongly preferred over ergocalciferol (D2) because it maintains serum levels longer and has superior bioavailability, especially with daily dosing. 1, 2

Why Not High-Dose Weekly Loading?

The 50,000 IU weekly regimen is reserved for true deficiency (<20 ng/mL), not insufficiency. 1, 2 Your level is close enough to the target that daily supplementation will efficiently bring you into the optimal range without the need for aggressive loading. 1

Essential Co-Interventions

• Ensure adequate calcium intake of 1,000–1,500 mg daily from diet plus supplements if needed—vitamin D cannot optimize bone health without sufficient calcium substrate. 1, 2, 4
• If taking calcium supplements, divide doses to no more than 600 mg at once for optimal absorption. 1
• Consider weight-bearing exercise at least 30 minutes, 3 days per week, to maximize bone health benefits. 1

Monitoring Protocol

• Recheck your 25-hydroxyvitamin D level after 3 months of supplementation to confirm adequate response—this allows sufficient time for levels to plateau given vitamin D's long half-life. 1, 2, 4
• Once you achieve ≥30 ng/mL, continue maintenance dosing (800–2,000 IU daily depending on your response) and recheck annually. 1, 2
• No need to monitor serum calcium unless you develop symptoms of hypercalcemia (nausea, constipation, confusion, excessive thirst)—toxicity is exceptionally rare at these doses. 1

Factors That May Increase Your Requirements

• Obesity: Vitamin D is sequestered in adipose tissue, potentially requiring 4,000–6,000 IU daily for adequate repletion. 4
• Dark skin pigmentation: Reduces cutaneous vitamin D synthesis, increasing supplementation needs. 1
• Age >65 years: Decreased skin synthesis efficiency and higher fracture risk warrant at least 800–1,000 IU daily. 1, 2
• Limited sun exposure: Indoor lifestyle, extensive clothing coverage, or high-latitude residence. 1
• Malabsorption syndromes: Inflammatory bowel disease, celiac disease, or post-bariatric surgery may require higher oral doses or intramuscular administration. 1, 4

Safety Considerations

• Daily doses up to 4,000 IU are completely safe for adults, with some evidence supporting up to 10,000 IU daily for several months without adverse effects. 1, 2, 4
• Toxicity typically only occurs with prolonged daily doses exceeding 10,000 IU or serum levels above 100 ng/mL. 1, 2
• Avoid single ultra-high loading doses (>300,000 IU) as they may be inefficient or potentially harmful for fall and fracture prevention. 1

Critical Pitfalls to Avoid

• Do not ignore this level thinking it's "close enough"—the difference between 28 ng/mL and 30 ng/mL is clinically meaningful for fracture prevention, particularly if you are elderly or have osteoporosis risk factors. 1, 2
• Do not use active vitamin D analogs (calcitriol, alfacalcidol) to treat nutritional insufficiency—these are reserved for advanced kidney disease with impaired 1α-hydroxylase activity and carry higher hypercalcemia risk. 1, 2, 4
• Do not rely on sun exposure alone due to skin cancer risk from UVB radiation—supplementation is safer and more reliable. 1
• Do not underdose with standard multivitamin amounts (typically 400 IU)—this is grossly inadequate for correcting insufficiency. 2

Expected Outcomes

With 1,000–2,000 IU daily supplementation, you should achieve a level of 30–40 ng/mL within 3 months, providing:

• 20% reduction in non-vertebral fractures and 18% reduction in hip fractures (if elderly). 1
• 19% reduction in fall risk (if taking 700–1,000 IU daily and elderly). 1
• Suppression of secondary hyperparathyroidism and preservation of bone mineral density. 3, 2