Contents
- 1 The total serum —————level gives the best estimate of vitamin D supply in the body
- 2 Which form of Vitamin -D is largely human-made and most commonly added to foods
- 3 Which form of vitamin-D is synthesized in the skin of humans
- 4 vitamin D3 (cholecalciferol) is synthesized in the skin of humans from
- 5 Vitamin D is activated by protein enzyme hydroxylation steps,
- 6 Which is physiologically active Vitamin-D?
- 7 Which is called ‘calcidiol’?
- 8 Major circulating form of vitamin D is
- 9 In-shorts
- 10 UV (UVB) radiation
The total serum —————level gives the best estimate of vitamin D supply in the body
A. Cholecalciferol
B. Calciferol
C. 25(OH)D
D. Ergocalciferol
Which form of Vitamin -D is largely human-made and most commonly added to foods
A. Cholecalciferol
B. Calciferol
C. 25(OH)D
D. Ergocalciferol
Which form of vitamin-D is synthesized in the skin of humans
A. vitamin-D2
B. vitamin-D3
C. 25(OH)D
D. vitamin-D2 and D3
vitamin D3 (cholecalciferol) is synthesized in the skin of humans from
A. Cholecalciferol
B. 7-dehydrocholesterol
C. 25(OH)D
D. Ergocalciferol
Vitamin D is activated by protein enzyme hydroxylation steps,
A. First in the kidney and the second in the liver
B. First in the liver and the second in the kidney
C. Liver only
D. Kidney only
Which is physiologically active Vitamin-D?
A. Cholecalciferol
B. 7-dehydrocholesterol
C. 25(OH)D
D. Calcitriol
Which is called ‘calcidiol’?
A. Cholecalciferol
B. 7-dehydrocholesterol
C. 25(OH)D
D. 1,25(OH)2D
Major circulating form of vitamin D is
A. Cholecalciferol
B. 7-dehydrocholesterol
C. 25(OH)D
D. 1,25(OH)2D
In-shorts
| vitamin D | ||
| 1 | vitamin D | calciferol |
| 2 | 25-hydroxyvitamin D [25(OH)D] | calcidiol |
| 3 | 1,25-dihydroxyvitamin D [1,25(OH)2D] | calcitriol |
| 4 | provitamin D-2 | Ergosterol |
| 4 | vitamin D2 | Ergocalciferol |
| 5 | vitamin D3 | Cholecalciferol |
| 6 | 7-dehydrocholesterol | Found in animals |
Serum concentration of 25(OH)D is currently the main indicator of vitamin D status.
In contrast to 25(OH)D, circulating 1,25(OH)2D is generally not a good indicator of vitamin D status because it has a short half-life measured in hours, and serum levels are tightly regulated by parathyroid hormone, calcium, and phosphate.
Levels of 1,25(OH)2D do not typically decrease until vitamin D deficiency is severe
| nmol/L* | ng/mL* | Health status |
|---|---|---|
| <30 | <12 | Associated with vitamin D deficiency, which can lead to rickets in infants and children and osteomalacia in adults |
| 30 to <50 | 12 to <20 | Generally considered inadequate for bone and overall health in healthy individuals |
| ≥50 | ≥20 | Generally considered adequate for bone and overall health in healthy individuals |
| >125 | >50 | Linked to potential adverse effects, particularly at >150 nmol/L (>60 ng/mL) |
UV (UVB) radiation
Type B UV (UVB) radiation with a wavelength of approximately 290–320 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3
