Vitamin-D-25-OH
S -D-25 KL 1220
Vitamin D is a fat-soluble vitamin that forms through the synthesis of 7-dehydrocholesterol in the skin, catalyzed by exposure to UV light from the sun. Some portion of vitamin D is also sourced from dietary elements such as mushrooms and fish. Following this, the liver initiates hydroxylation, transforming it into 25-OH vitamin D (calcidiol), which constitutes the predominant circulating form in the bloodstream. The biologically active variant, named 1,25-dihydroxy vitamin D (calcitriol), arises via 1-hydroxylation within the kidneys. Calcitriol operates as a hormone, influencing calcium and phosphorus metabolism, thereby augmenting their absorption. Beyond this pivotal role, vitamin D contributes to numerous other aspects of holistic well-being, with comprehensive research delving into its potential to prevent various ailments. It is noteworthy that the body inherently generates the active form of calcitriol (1,25-dihydroxy vitamin D).
Indications
Regularly assessing vitamin D treatment is crucial, especially for individuals at higher risk, including elderly individuals, pregnant women, children under the age of 2 who are not receiving vitamin D supplements, and people with restricted sunlight exposure (such as inpatients).
Preparation
Blood sample. Normal eating and drinking is allowed.
No vitamin D supplements 12 hours before sampling.
Sample
1.5 mL (minimum 1 mL) of serum
Storage and delivery
Delivery at room temperature on the sampling day if it arrives the next day (Mon-Fri). Can be stored refrigerated over the weekend, ship at room temperature.
Method
Liquid chromatography (HPLC)
Turnaround time
5 – 10 weekdays
Reference ranges
| below 25 nmol/L | serious deficiency |
| below 50 nmol/L | deficiency |
| 50-75 nmol/L | generally regarded as sufficient concentration |
| 75-120 nmol/L | recommended concentration |
| over 375 nmol/L | toxic concentration |
Inquiries
martin.tornudd@milalab.fi
Last update 8.8.2023
