Vitamin D is called a "vitamin" because of its exogenous source, predominately
from oily fish in the form of vitamin D 2 and vitamin D 3. It is more accurate
to consider fat-soluble Vitamin D as a steroid hormone, synthesized by the
skin and metabolized by the kidney to an active hormone, calcitriol. Clinical
disorders related to vitamin D may arise because of altered availability of
the parent vitamin D, altered conversion of vitamin D to its predominant
metabolites, altered organ responsiveness to dihydroxylated metabolites and
disturbances in the interactions of the vitamin D metabolites with PTH and
calcitonin. Normal levels of Vitamin D range from 20 - 50 ng/ml. This LCD
identifies the indications and limitations of Medicare coverage and
reimbursement for the lab assay.  
  
 **Indications:**  
  
Measurement of 25-OH Vitamin D level is indicated for patients with:

    * chronic kidney disease stage III or greater

    * cirrhosis

    * hypocalcemia

    * hypercalcemia

    * hypercalciuria

    * hypervitaminosis D

    * parathyroid disorders

    * malabsorption states

    * obstructive jaundice

    * osteomalacia

      * osteoporosis if
i. T score on DEXA scan <-2.5 or ii. History of fragility fractures or iii.
FRAX > 3% 10-year probability of hip fracture or 20% 10-year probability of
other major osteoporotic fracture or  iv. FRAX > 3% (any fracture) with
T-score <-1.5 or v. Initiating bisphosphanate therapy (Vitamin D level should
be determined and managed as necessary

_before bisphosphonate is initiated)_

  * osteosclerosis/petrosis
  * rickets
  * vitamin D deficiency on replacement therapy related to a condition listed above; to monitor the efficacy of treatment.

  
Measurement of 1, 25-OH Vitamin D level is indicated for patients with:

    * unexplained hypercalcemia (suspected granulomatous disease or lymphoma)

    * unexplained hypercalciuria (suspected granulomatous disease or lymphoma)

    * suspected genetic childhood rickets

    * suspected tumor-induced osteomalacia

  * nephrolithiasis or hypercalciuria

  
**Limitations:**  
  
Testing may not be used for routine or other screening.  
  
Both assays of vitamin D need not be performed for each of the above
conditions. Often, one type is more appropriate for a certain disease state
than another. The most common type of vitamin D deficiency is 25-OH vitamin D.
A much smaller percentage of 1, 25-dihydroxy vitamin D deficiency exists;
mostly, in those with renal disease. Although it is not the active form of the
hormone, 25-OH vitamin D is much more commonly measured because it better
reflects the sum total of vitamin D produced endogenously and absorbed from
the diet than does the level of the active hormone 1, 25-dihydroxy vitamin D.
Deficiency of 1, 25-dihydroxy vitamin D, which is present at much lower
concentrations, does not necessarily reflect deficiency of 25-OH vitamin D and
its measurement should be limited to the indications listed. Documentation
must justify the test(s) chosen for a particular disease entity. Various
component sources of 25-OH vitamin D, such as stored D or diet-derived D,
should not be billed separately.  
  
Once a beneficiary has been shown to be vitamin D deficient, further testing
may be medically necessary only to ensure adequate replacement has been
accomplished. If Vitamin D level is between 20 and 50 ng/ml and patient is
clinically stable, repeat testing is often unnecessary; if performed,
documentation most clearly indicate the necessity of the test. If level <20
ng/ml or > 60 ng/ml, a subsequent level(s) may be reimbursed until the level
is within the normal range.