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Test Code DHVD 1,25-Dihydroxyvitamin D, Serum

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

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

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.

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.

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

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.

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.

Clinical Reference

1. Endres DB, Rude RK: Vitamin D and its metabolites. In Tietz Textbook of Clinical Chemisty. Third edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1999, pp 1417-1423

2. Bringhurst FR, Demay MB, Kronenberg HM: Vitamin D (calciferols): metabolism of vitamin D. In Williams Textbook of Endocrinology. Ninth edition. Edited by JD Wilson, DW Foster, HM Kronenberg, PR Larsen. Philadelphia, WB Saunders Company, 1998, pp 1166-1169

Analytic Time

2 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Method Name

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