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Test Code LAB1323 1,25-Dihydroxyvitamin D, Serum

Additional Codes

Test Name in Epic EPIC Test Code  Mnemonic Mayo Test ID
VITAMIN D, 1,25-DIHYDROX LAB1323 VD125 DHVD

 

Reporting Name

1,25-Dihydroxyvitamin D, S

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-dihydroxy vitamin D)

 

Differential diagnosis of hypercalcemia

Method Name

Extraction/Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Patient Preparation: Fasting (4-hour preferred but not required)

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: At least 1.5 mL


Specimen Minimum Volume

0.7 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  28 days
  Ambient  7 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Reference Values

Males

<16 years: 24-86 pg/mL

≥16 years: 18-64 pg/mL

Females

<16 years: 24-86 pg/mL

≥16 years: 18-78 pg/mL

Day(s) and Time(s) Performed

Monday through Friday; 3 p.m.

CPT Code Information

82652

LOINC Code Information

Test ID Test Order Name Order LOINC Value
DHVD 1,25-Dihydroxyvitamin D, S 62290-2

 

Result ID Test Result Name Result LOINC Value
8822 1,25-Dihydroxyvitamin D, S 62290-2

Interpretation

1,25-Dihydroxy vitamin D concentrations are low in chronic renal failure and hypoparathyroidism.

 

1,25-Dihydroxy vitamin D concentrations are high in sarcoidosis and other granulomatous diseases, some malignancies, primary hyperparathyroidism, and physiologic hyperparathyroidism.

 

1,25-dihydroxy vitamin D concentrations are not a reliable indicator of vitamin D toxicity; normal (or even low) results may be seen in such cases.

Cautions

No significant cautionary statements.

Supportive Data

The new, 1,25-dihydroxy vitamin D liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay correlates well with the current immunoassay:

-LC-MS/MS=0.95 RIA (pg/mL) + 2.5 pg/mL; correlation coefficient=0.822

-Inter-assay precision: 7 to 12% CV (19 to 287 pg/mL)

-Interferences: C-3 epimers (EPI) of 1,25 dihydroxyvitamin D3 3.0%

Method Description

Deuterated stable isotopes (d3-1,25 dihydroxyvitamin D3 [DHVD3-d3] and d6-1,25 dihydroxyvitamin D2 [DHVD2-d6]) are added to a 1-mL plasma sample as internal standard. 1,25-Dihydroxyvitamin D2 (DHVD2), 1,25-dihydroxyvitamin D3 (DHVD3), and the internal standard are extracted using acetonitrile precipitation. The extracts are then further purified by SPE and affinity extraction. Extracts are then derivatized using 4-phenyl-1, 2,4-triazoline-3,5-dione and analyzed by chromatography-tandem mass spectrometry using multiple reaction monitoring with a C18 turbo cleanup for excess derivatizing reagent. DHVD2 and DHVD3 are quantified and a total is reported with a clinical reference range attached to the total DHVD.(Unpublished Mayo method)

Analytic Time

2 days

Specimen Retention Time

2 weeks

Clinical Information

Vitamin D is a generic designation for a group of fat-soluble, structurally similar sterols including ergocalciferol D2 from plants and cholecalciferol D3 from animals. Vitamin D in the body is derived from 2 sources: exogenous (dietary: D2 and D3) and endogenous (biosynthesis: D3). Endogenous D3 is produced in the skin from 7-dehydrocholesterol, under the influence of ultraviolet light. Both forms of vitamin D are of similar biologic activity.

 

Vitamin D is rapidly metabolized in the liver to form 25-hydroxy (OH) vitamin D. Additional hydroxylation of 25-OH vitamin D takes place in the kidney by 1-alpha hydroxylase, under the control of parathyroid hormone, to yield 1,25-dihydroxy vitamin D.

 

1,25-Dihydroxy vitamin D is the most potent vitamin D metabolite. It stimulates calcium absorption in the intestine and its production is tightly regulated through concentrations of serum calcium, phosphorus, and parathyroid hormone.

 

1,25-Dihydroxy vitamin D 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 may have elevated 1,25-dihydroxy vitamin D levels and hypercalcemia.

 

1,25-Dihydroxy vitamin D levels are decreased in hypoparathyroidism and in chronic renal failure.

 

While 1,25-dihydroxy vitamin D is the most potent vitamin D metabolite, levels of the 25-OH forms of vitamin D more accurately reflect the body's vitamin D stores. Consequently, 25HDN / 25-Hydroxyvitamin D2 and D3, Serum is the preferred initial test for assessing vitamin D status. However, in the presence of renal disease, 1,25-dihydroxy vitamin D levels may be needed to adequately assess vitamin D status.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.