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Cholecalciferol - Calcidiol - Calcitriol

Cholecalciferol -> Calcidiol

Vitamin D: cholecalciferol, which is formed by the sun or taken up with food supplements, becomes what is known as liver in the liver
Calcidiol or 25-hydroxy-vitamin D3 (short: 25 (OH) D) converted.
The calcidiol level is determined in standard blood tests and provides a reliable picture of a patient's vitamin D status. Calcidiol is a precursor to active vitamin D3.

Calcidiol reference values

The calcidiol values ​​are in the reference range 80-220 nmol / l.

Calcidiol -> Calcitriol

In order to activate the vitamin, calcidiol in the kidneys or in the cells is converted into the actually active vitamin D hormone calcitriol.
Calcitriol = active vitamin D or 1,25-dihydroxycholecalciferol (short: 1,25- (OH) 2D)).

Calcitriol reference values

the calcitriol values ​​are usually between 50 - 130 pmol / l.

What are the differences between calcidiol and calcitriol?


  • Is formed in the liver
  • Also known as 25-hydroxy vitamin D3 or 25 (OH) D
  • Standard marker in the blood test to determine the vitamin D status
  • Is the body among other things stored in the blood and liver
  • The body's supply is reduced within a few weeks, sometimes even months


  • Is formed in the kidney and in the endocrine system (it is a hormone)
  • 1,25-dihydroxycholecalciferol (or 1,25- (OH) 2D))
  • Is broken down and excreted from the body within a few days

Effect and safety of high doses of vitamin D3

If you choose a supplement with a high dose of vitamin D, replenish your vitamin D stores with the passive form of the vitamin.
Your body knows how much it needs to convert into active vitamin D as needed.

This process can be compared to the conversion of ferritin to iron.
Ferritin is a passive form of iron, the so-called iron depot. The iron and Hb blood values ​​serve as an important indicator of anemia.

Overdose and toxicity of vitamin D

The risk of a possible overdose or vitamin D poisoning with hypercalcaemia and hypercalciuria only increases from a calcidiol level, 25 (OH) D above 220-250 nmol/l.

For people who live near the equator or people in our latitudes who often expose themselves to the sun and do not wear light-proof clothing or use sunscreen, the calcidiol level can rise to up to 225 nmol/l through the body's own vitamin D synthesis , This increase has no adverse health effects.

> Buy high-dosed vitamin D3

Increased calcitriol values ​​(active vitamin D)

Elevated levels of 1,25-dihydroxy-vitamin D with low passive 25 (OH) D values ​​indicate that the body cannot convert vitamin D adequately.
In this case, supplementation is strongly discouraged, since further examinations are necessary.
Doctors and specialists usually measure the active vitamin D level in patients whose risk of reduced vitamin D intake due to bowel diseases (e.g. Crohn's disease or celiac disease) or impaired kidney function is increased.

Autoimmune diseases and obesity can also be causal factors for low vitamin D levels. These cases require a careful medical examination before deciding on an appropriate supplement.