Clotted blood tube
(Serum gel separator clot activator tube)
Minimum blood volume: 5 mL
Paediatric clotted blood tube
Number of vials: 1
Minimum blood volume: 0.8 mL
Blood sample should be collected before starting vitamin D supplement unless there is doubt whether the vitamin is being absorbed.
A fasting specimen is recommended.
Total 25OH Vitamin D:
| < 12.5 nmol/L | Severe deficiency |
| 12.5 - 29 nmol/L | Moderate deficiency |
| 30 - 49 nmol/L | Mild deficiency |
| 50 - 220 nmol/L | Sufficient |
| > 220 nmol/L | Potentially toxic |
(Source:
1. Med J Aust 2012; 196 (11): 686 - 7
2. Med J Aust 2013; 198 (3): 142 - 3)
Investigation of suspected rickets and osteomalacia (e.g. malabsorption, dietary deficiency).
Investigation of suspected vitamin D toxicity (e.g. hypercalcaemia, nephrocalcinosis, overdose).
Serum total 25-hydroxyvitamin D (25OHD) concentration, mainly the sum of serum 25-hydroxyvitamin D2 and D3 concentrations, is used to evaluate vitamin D status. The biologically active forms of the hormone are 1,25-dihydroxyvitamin Ds which regulate calcium and phosphorous homeostasis. Although 25OHD is usually reliable for the diagnosis of abnormal vitamin D status, in a few instances (e.g. sarcoidosis, oncogenic osteomalacia), 1,25-dihydroxyvitamin D alone is abnormal.