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Vitamin D with C-Reactive Protein (Inflammation Assessment)

Test ID: A904

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Vitamin D is a fat-soluble vitamin that is naturally present in a few foods, and is produced endogenously when ultraviolet (UV) rays from sunlight trigger vitamin D synthesis. Low dietary intake, limited sun exposure, and poor vitamin D absorption can result in vitamin D deficiency. This results in rickets in children and osteomalacia in adults. Symptoms can include soft bones, skeletal deformities, failure to thrive, developmental delay, and dental abnormalities.

C-reactive protein (CRP) concentration rises non-specifically in response to inflammation. Measurements of CRP are useful for detecting infections and other medical conditions.



How to order a test

What is Included?

Measurement of blood vitamin D levels by chemiluminescent microparticle immunoassay.

Measurement of C-reactive protein to aid in the assessment of inflammation.

Turnaround Time

1 – 3 business days
The turnaround time is not guaranteed. The average turnaround time is 1 – 3 business days from the date that the sample arrives at the laboratory. Shipping time for the sample is not included. Additional time is required if the case requires confirmatory or reflex testing, or if the sample is insufficient, or if a recollection is required.

Related Documents

Additional Information and Resources


Preparation Before Specimen Collection


Specimen Type



50 μL in a microtainer


Microtainer (regular blood tube)

Collection Method

This test requires a blood sample from a finger prick. All supplies for sample collection are provided in the kit.

  1. First wash and dry hands. Warm hands aid in blood collection.
  2. Clean the finger prick site with the alcohol swab and allow to air dry.
  3. Use the provided lancet to puncture the skin in one quick, continuous and deliberate stroke.
  4. Wipe away the first drop of blood.
  5. Massage hand and finger to increase blood flow to the puncture site. Angle arm and hand downwards to facilitate blood collection on the fingertip.
  6. Drip blood into the microtainer tube.
  7. Dispose of all sharps safely and return sample to the laboratory in the provided prepaid return shipping envelope.

NOTES: Avoid squeezing or ‘milking’ the finger excessively. If more blood is required and blood flow stops, perform a second skin puncture on another finger. Do not touch the fingertip.

Specimen Storage

Maintain specimen at temperatures between 2°C and 30°C during storage and transport.

Specimen Stability

Blood samples can be refrigerated or kept at room temperature for up to 7 days.

Causes for Rejection

  • Incorrect or incomplete patient identification
  • Incorrect specimen collection
  • Inappropriate storage and transport conditions
  • Incorrect specimen volume
  • Gross lipemia



To measure vitamin D levels in a blood sample for the detection of vitamin D deficiency.

To measure C-reactive protein (CRP) levels in a blood sample for the evaluation of inflammation.


  • This report is not intended for use in medico-legal applications.
  • These results should be interpreted in conjunction with other laboratory and clinical information.
  • Correct specimen collection and handling is required for optimal assay performance.
  • False results may occur in specimens from individuals that have received preparations of mouse monoclonal antibodies for diagnosis or therapy. Additional clinical or diagnostic information may be required for these specimens.
  • Assay interference may occur in specimens from individuals routinely exposed to animals or to animal serum products. Additional clinical or diagnostic information may be required for these specimens.
  • Serum specimens containing rheumatoid factor may interfere with this assay.
  • This assay is susceptible to interference effects from triglycerides > 500 mg/dL.
  • Gammopathy, particularly of the monoclonal IgM type may interfere with this assay.


Chemiluminescent microparticle immunoassay (Alinity i 25-OH Vitamin D assay)

Turbidimetric/Immunoturbidometric (Alinity c CRP Vario assay)

Reference Intervals

Vitamin D:
Severe deficiency: < 10 ng/mL
Mild to moderate deficiency: 10 – 24 ng/mL
Optimum levels: 25 – 80 ng/mL
Toxicity possible: > 80 ng/mL

These reference ranges were obtained from “Laboratory Reference Ranges” from the Endocrine Society.

C-Reactive Protein:
< 5.0 mg/L

This reference range was obtained from Dati F, Johnson AM, Whicher JT. The existing interim consensus reference ranges and the future approach. Clin Chem Lab Med. 2001 Nov;39(11):1134-6.