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🏥 Gotokuji Orthopedic Clinic / Patient Guide

Vitamin D Test (25-OH)

Is your vitamin D level enough for healthy bones?

The 25-OH vitamin D test is a blood test that measures your stored vitamin D level.
Vitamin D is essential for building strong bones and helps your body absorb calcium.
When vitamin D is low, bones become weak, raising the risk of osteoporosis and fractures.
When vitamin D is low, muscle strength can decline, making falls more likely. A link with immune function has also been reported, but the evidence is not yet conclusive.
Many people have low vitamin D levels, especially older adults and those who spend most of their time indoors.

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Helps absorb calcium

Promotes calcium absorption from the gut, making bones stronger

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Essential for bone formation and maintenance

Keeps bone metabolism working normally and helps maintain bone density

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Maintains muscle strength

When vitamin D is low, muscle strength declines and fall risk increases

4
Link with immunity still under study

A link with immune function has been reported, but the evidence is not yet conclusive

30 ng/mL or above — Sufficient (ideal level)
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20-29 ng/mL — Insufficient (supplementation recommended)
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Below 20 ng/mL — Deficient (please consult your doctor)
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Insurance coverage is limited to specific conditions (we do not offer this as a self-paid test)
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Done after consultation, such as when choosing an osteoporosis medication
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Sunlight
About 15 minutes of sunlight per day helps your skin produce vitamin D
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Diet
Eat vitamin D-rich foods such as salmon, sardines, whitebait, and mushrooms
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Supplements
If diet and sunlight are not enough, supplements can help fill the gap
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Active Vitamin D Medication
For osteoporosis treatment, your doctor may prescribe active vitamin D
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Take with Calcium
Taking vitamin D together with calcium improves absorption
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Regular Blood Tests
While on active vitamin D medication, calcium levels are checked every 3-6 months
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Vitamin D is the key to bone health

Many people have insufficient vitamin D levels. This is especially true for older adults, people who spend most of their time indoors, and those being treated for osteoporosis. Whether a test is needed is something to discuss with your doctor at your visit. If it is low, you can supplement through sunlight, diet, and supplements.

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For patients taking active vitamin D medication
If you are taking active vitamin D medication (such as alfacalcidol or eldecalcitol), there is a risk of your blood calcium levels rising too high. Please have regular blood tests (within 1 month at first, then every 3-6 months; every 3 months for older adults) to monitor your kidney function and calcium levels.

💡 Make Vitamin D Your Ally

  • Get 15 minutes of sunlight daily (even just on your hands and face)
  • Include fish and mushrooms in your meals regularly
  • If you are being treated for osteoporosis, do not skip your regular check-ups
  • Wondering about your vitamin D level? Please ask at your visit whether a test is needed