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Vitamins

Vitamin D levels, fall risk and fractures

Your vitamin D levels show how much reserve you have to absorb calcium. Bones and muscles are the first to notice an empty store. How the number is read depends on your age.

Below seventy, 40 nmol/l counts as insufficiency. From seventy, the same result is a deficiency. So the value is rarely read on its own.

It is read alongside calcium, phosphate and parathyroid hormone. Your medication counts too. Some anticonvulsants and long-term corticosteroids speed up the breakdown.

Doctor's Assessment Included

When is this value abnormal?

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

up to 69 years Your group

Decision limits per result, in nmol/l
Result Value (nmol/l)
Deficiency < 30
Sufficient ≥ 30

70 years and older Your group

Decision limits per result, in nmol/l
Result Value (nmol/l)
Severe deficiency < 35
Deficiency 35–50
Sufficient ≥ 50

Nederlandse richtlijnen zijn het niet eens over deze grens. Het Zorginstituut stelt vast: "Er ontbreekt een eenduidige grens voor vitamine D-deficiëntie" (2022). Wij volgen de Gezondheidsraad, het NHG en het Farmacotherapeutisch Kompas. De NVKC hanteert 50 nmol/l voor iedereen; de osteoporoserichtlijn hanteert 50 nmol/l bij verhoogd fractuurrisico.

Source: Gezondheidsraad Reference population: Nederlandse bevolking (Gezondheidsraad 2012)

Source: Zorginstituut Nederland Reference population: Nederlandse bevolking (Gezondheidsraad 2012)

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Vitamin D (25-OH): what this test measures

The test measures 25-hydroxyvitamin D, or 25-OH-D, reported in nmol/l. This is the storage form, made in the liver. It stays in the blood for two to three weeks. The result therefore reflects the supply of recent months, not of yesterday.

The active hormone, 1,25-dihydroxyvitamin D, is deliberately left out. The kidney makes it under the direction of parathyroid hormone. It clears from the blood within hours.

When the store runs dry, the body steps up that production. The active value can then look normal or even high in a clear deficiency. Measuring only that hormone misses an empty store entirely.

Ask for total 25-OH-D, meaning D2 and D3 together. Some immunoassays recover D2 poorly. That matters if you take a plant-based D2 supplement. Reference values also differ from one laboratory to the next.

Vitamin D (25-OH): why this value matters

Vitamin D governs how much calcium you absorb from your food. When the store is empty, that absorption drops. The parathyroid glands then work harder and release more parathyroid hormone.

They pull calcium out of the skeleton to protect the blood level. The blood still looks normal while the bone pays.

AgeDeficiency belowLinked to fewer fractures
Under 7030 nmol/lfrom 50 nmol/l
70 and over50 nmol/lfrom 50 nmol/l; above 75 nmol/l desirable where there is fall risk

That shift at seventy is not a formality. The same 45 nmol/l counts as tight at fifty. At seventy-five it is a deficiency. Vitamin D also acts in muscle.

A shortage takes its toll on the hip girdle first. Those are the muscles you use to get out of a chair. And to catch your balance when you trip. That is where a low number connects to a broken hip.

Above 75 nmol/l the evidence for hard outcomes is thin. It is not a number to climb towards. And the result never stands alone. If parathyroid hormone is raised while 25-OH-D is low, that is secondary hyperparathyroidism.

The body is then already compensating at the expense of bone. That picture weighs more than the vitamin figure alone. So calcium and phosphate belong on the same request.

Vitamin D (25-OH): when is testing worthwhile?

Test if you are seventy or older and fall risk is in play. The line sits higher at that age. A result that once sufficed may now be too low.

Test too with muscle weakness in the hip girdle, difficulty standing up, or an unsteady gait. That is precisely the route from a low value to a fracture.

Do you use anticonvulsants, rifampicin or glucocorticoids long term? They speed up breakdown. Discuss testing with your GP.

Vitamin D (25-OH): symptoms of a high or low value

Low Levels

A shortage stays silent for a long time. If you do notice something, it rarely looks like vitamin D:

  • getting up out of a low chair takes effort
  • stairs cost more than they did
  • your walking feels less steady
  • a dull ache in bones or muscles

That is the difficulty. Such complaints are easily put down to age. A measurable cause may sit underneath. If a shortage persists for years, new bone tissue mineralises poorly.

In adults that is called osteomalacia, with bone pain and muscle weakness. The chance of fractures rises with it. Complaints like these fit dozens of causes. So the number starts the conversation; it is not the proof.

High Levels

A high result almost always comes from a bottle, not the sun. The skin stops making more once there is enough. Toxicity with a raised calcium is seen only well above 250 nmol/l.

Prolonged, very high intake comes first. If you take several products at once, the totals add up unnoticed. Think of a multivitamin next to a separate preparation.

There is one exception that matters more. In sarcoidosis, tuberculosis and some lymphomas, macrophages make the active form themselves. This happens in inflamed tissue, outside the normal brake.

Calcium can then rise while 25-OH-D looks perfectly ordinary. A raised calcium alongside vitamin D is a question for your GP.

Vitamin D (25-OH): what to do about an abnormal value

Male

If Low

Low vitamin D may cause fatigue, muscle weakness, and bone pain. Consider 2000-5000 IU daily supplementation and increase sun exposure.

If High

High vitamin D may indicate excessive supplementation. Reduce supplement dose and retest in 3 months.

Female

If Low

Low vitamin D may cause fatigue, muscle weakness, and bone pain. Consider 2000-5000 IU daily supplementation and increase sun exposure.

If High

High vitamin D may indicate excessive supplementation. Reduce supplement dose and retest in 3 months.

Vitamin D (25-OH): lifestyle and this value

At 52 degrees north the sun sits too low from October through March. The UVB your skin needs (290 to 315 nanometres) barely reaches the ground. For those months you live off your summer store.

So note the month of your blood draw. A March result belongs next to another March result. Not next to one from September.

Other things that push production down:

  • darker skin, because melanin absorbs UVB
  • covering clothing
  • little time outdoors, or working nights
  • excess weight, because vitamin D is held in fat tissue
  • ageing, because the skin holds less 7-dehydrocholesterol
  • impaired fat absorption in the gut

Pay separate attention to your medication list. These speed up the breakdown of vitamin D:

  • enzyme-inducing anticonvulsants
  • rifampicin
  • glucocorticoids taken long term

That hits precisely the people who need them year after year. The Dutch Health Council advises certain groups to supplement. They include everyone from seventy onwards and people with darker skin. People who are rarely outdoors are on that list too.

How much is a question for your GP or the Voedingscentrum. If you take high-dose biotin, say so at the blood draw. It can falsely raise some 25-OH-D assays.

Vitamin D (25-OH): frequently asked questions

I have just turned seventy. Does my threshold change?

Yes. Under seventy anything below 30 nmol/l is deficiency; from seventy that line sits at 50 nmol/l. Above 75 nmol/l is desired where there is fall risk. Your result did not change, the yardstick did.

What does vitamin D have to do with falling?

A low value is associated with muscle weakness in the hip girdle. That weakness makes standing up and stairs unsteady. Unsteady walking raises the chance of a fall. A fall at that age often means a fracture.

Why does the doctor also look at calcium and parathyroid hormone?

Because those three together tell the story. When the reserve empties, parathyroid hormone rises to hold calcium steady. A low vitamin D with a raised parathyroid hormone is secondary hyperparathyroidism. That weighs more than the vitamin D figure alone.

Can my medication lower my value?

It can. Enzyme-inducing drugs such as anticonvulsants and rifampicin speed up breakdown. Glucocorticoids do the same. If you use them long term, discuss with your GP whether testing is worthwhile.

Test Products

This marker is included in the following test panels.

Heart & Metabolism

GLP-1 Extended Panel

The 6-month measurement: everything from the check-in plus insulin, ApoB and your nutrients — especially relevant if you have been eating much less for a while.

Insulin (Fasting) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) HDL Cholesterol HbA1c (Glycated Hemoglobin) ApoB (Apolipoprotein B) Vitamin B12 Ferritin Potassium Sodium Glucose (Fasting) Total Cholesterol Albumin Lipase Creatinine Vitamin D (25-OH) Triglycerides
€196,-
Heart & Metabolism

GLP-1 Baseline Panel

Your starting point before the first injection: blood sugar, cholesterol, pancreas, liver, kidneys, thyroid and nutrients in one measurement.

Insulin (Fasting) ALT (Alanine Aminotransferase) TSH (Thyroid Stimulating Hormone) AST (Aspartate Aminotransferase) HDL Cholesterol HbA1c (Glycated Hemoglobin) Bilirubin (Total) ApoB (Apolipoprotein B) Vitamin B12 Ferritin Potassium Sodium Glucose (Fasting) Total Cholesterol Albumin Lipase Creatinine Vitamin D (25-OH) Triglycerides Bilirubin (Direct) Bilirubin (Indirect)
€214,-

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Vitamin D (25-OH)

€35,-