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24929 Vitamin D, 1,25 Dihydroxy (DHVD)

Vitamin D, 1,25 Dihydroxy (DHVD)
Test Code: VIT-D3
Synonyms/Keywords
 1,25-Dihydroxy Vitamin D, 1,25-Dihydroxycholecalciferol, 1,25-Dihydroxyvitamin D3, Calcitriol
Useful For
As a second-order test in the assessment of vitamin D status, especially in patients with renal disease
 
Investigation of some patients with clinical evidence of vitamin D deficiency (eg, vitamin D-dependent rickets due to hereditary deficiency of renal 1-alpha hydroxylase or end-organ resistance to 1,25-dihydroxyvitamin D)
 
Differential diagnosis of hypercalcemia​
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Yes (4-hour preferred but not required) ​Serum ​Red Top Tube (RTT) ​Serum Separator Tube (SST) ​1.5 mL 1.2 mL
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ ​Refrigerated (preferred) ​7 days
​Frozen ​28 days
​Ambient ​7 days
Rejection Criteria
Hemolysis Gross
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday​ ​2 days
Extraction/Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
Test Information
Vitamin D is a generic designation for a group of fat-soluble, structurally similar sterols, which act as hormones. In the presence of renal disease or hypercalcemia, testing of 1,25-dihydroxy vitamin D (DHVD) might be needed to adequately assess vitamin D status. The 25-hydroxyvitamin D (25HDN) test (25HDN / 25-Hydroxyvitamin D2 and D3, Serum) in serum is otherwise the preferred initial test for assessing vitamin D status and most accurately reflects the body's vitamin D stores.
 

Vitamin D compounds in the body are exogenously derived by dietary means; from plants as 25-hydroxyvitamin D2 (ergocalciferol or calciferol) or from animal products as 25-hydroxyvitamin D3 (cholecalciferol or calcidiol). Vitamin D may also be endogenously derived by conversion of 7-dihydrocholesterol to 25-hydroxyvitamin D3 in the skin upon ultraviolet exposure.

25HDN is subsequently formed by hydroxylation (CYP2R1) in the liver. 25HDN is a prohormone that represents the main reservoir and transport form of vitamin D, being stored in adipose tissue and tightly bound by a transport protein while in circulation. Biological activity is expressed in the form of DHVD, the active metabolite of 25HDN. 1-Alpha-hydroxylation (CYP27B1) occurs on demand, primarily in the kidneys, under the control of parathyroid hormone (PTH) before expressing biological activity. Like other steroid hormones, DHVD binds to a nuclear receptor, influencing gene transcription patterns in target organs.

25HDN may also be converted into the inactive metabolite 24,25-dihydroxyvitamin D (24,25D) by (CYP24A1) hydroxylation. This process, regulated by parathyroid hormone (PTH), might increase DHVD synthesis at the expense of the alternative hydroxylation (CYP24A1) product 24,25D. Inactivation of 25HDN and DHVD by CYP24A1 is a crucial process that prevents over production of DHVD and resultant vitamin D toxicity.

DHVD stimulates calcium absorption in the intestine and its production is tightly regulated through concentrations of serum calcium, phosphorus, and PTH. DHVD promotes intestinal calcium absorption and, in concert with PTH, skeletal calcium deposition, or less commonly, calcium mobilization. Renal calcium and phosphate reabsorption are also promoted, while prepro-PTH mRNA expression in the parathyroid glands is downregulated. The net result is a positive calcium balance, increasing serum calcium and phosphate levels, and falling PTH concentrations.

In addition to its effects on calcium and bone metabolism, DHVD regulates the expression of a multitude of genes in many other tissues including immune cells, muscle, vasculature, and reproductive organs.

DHVD levels are decreased in hypoparathyroidism and in chronic renal failure. DHVD levels may be high in primary hyperparathyroidism and in physiologic hyperparathyroidism secondary to low calcium or vitamin D intake. Some patients with granulomatous diseases (eg, sarcoidosis) and malignancies containing nonregulated 1-alpha hydroxylase in the lesion might have hypercalcemia that appears vitamin D mediated with normal or high serum phosphate (hyperphosphatemia) and hypercalcemia (both of which might be severe) in addition to low PTH and absent parathyroid hormone-related peptide (PTHRP). Assessment of 24,25D might also be required in patients with hypercalcemia that does not appear to be driven by PTH or PTHRP, and may be helpful in assessment of patients with loss of function inactivating CYP24A1 mutations. Differential diagnostic considerations include vitamin D intoxication and CYP24A1 deficiency.

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​
Males:
<16 years: 24-86 pg/mL
> or =16 years: 18-64 pg/mL​
Females:
<16 years: 24-86 pg/mL
> or =16 years: 18-78 pg/mL​
Interpretation
1,25-Dihydroxyvitamin D (DVHD) concentrations are low in chronic renal failure and hypoparathyroidism.
 
1,25-Dihydroxyvitamin D (DVHD) concentrations are high in sarcoidosis and other granulomatous diseases, some malignancies, primary hyperparathyroidism, and physiologic hyperparathyroidism.
 
1,25-dihydroxyvitamin D (DVHD) concentrations are not a reliable indicator of vitamin D toxicity; normal (or even low) results may be seen in such cases.
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​82652
Synonyms/Keywords
 1,25-Dihydroxy Vitamin D, 1,25-Dihydroxycholecalciferol, 1,25-Dihydroxyvitamin D3, Calcitriol
Ordering Applications
Ordering Application Description
​Centricity ​Vit D (1,25 dihydroxy) (8822)
​Cerner ​Vitamin D, 1,25 Dihydroxy (8822)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Yes (4-hour preferred but not required) ​Serum ​Red Top Tube (RTT) ​Serum Separator Tube (SST) ​1.5 mL 1.2 mL
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ ​Refrigerated (preferred) ​7 days
​Frozen ​28 days
​Ambient ​7 days
Rejection Criteria
Hemolysis Gross
Useful For
As a second-order test in the assessment of vitamin D status, especially in patients with renal disease
 
Investigation of some patients with clinical evidence of vitamin D deficiency (eg, vitamin D-dependent rickets due to hereditary deficiency of renal 1-alpha hydroxylase or end-organ resistance to 1,25-dihydroxyvitamin D)
 
Differential diagnosis of hypercalcemia​
Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​
Males:
<16 years: 24-86 pg/mL
> or =16 years: 18-64 pg/mL​
Females:
<16 years: 24-86 pg/mL
> or =16 years: 18-78 pg/mL​
Interpretation
1,25-Dihydroxyvitamin D (DVHD) concentrations are low in chronic renal failure and hypoparathyroidism.
 
1,25-Dihydroxyvitamin D (DVHD) concentrations are high in sarcoidosis and other granulomatous diseases, some malignancies, primary hyperparathyroidism, and physiologic hyperparathyroidism.
 
1,25-dihydroxyvitamin D (DVHD) concentrations are not a reliable indicator of vitamin D toxicity; normal (or even low) results may be seen in such cases.
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Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday​ ​2 days
Extraction/Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​82652
For most current information refer to the Marshfield Laboratory online reference manual.