How To Use CPT Code 84100

CPT 84100 describes the testing of inorganic phosphorus (phosphate) levels in a patient specimen, such as serum. This article will cover the description, procedure, qualifying circumstances, appropriate usage, documentation requirements, billing guidelines, historical information, similar codes and billing examples.

1. What is CPT Code 84100?

CPT 84100 can be used to describe the testing of inorganic phosphorus (phosphate) levels in a patient specimen, such as serum. This code is used when a lab analyst performs a test to evaluate the level of phosphate in the specimen, which is an inorganic chemical involved in processes like the metabolism of carbohydrates.

2. Official Description

The official description of CPT code 84100 is: ‘Phosphorus inorganic (phosphate).’ There are no additional notes available for this code.

3. Procedure

1. The lab analyst receives a patient specimen, such as serum, for testing.
2. The lab analyst prepares the specimen by adding a reagent, such as phosphomolybdate, to induce a chemical reaction.
3. The chemical reaction leads to a color change in the specimen.
4. The lab analyst uses colorimetry, a quantitative analysis procedure, to compare the color of the tested sample solution to a standard solution.
5. The lab analyst evaluates the color change to determine the level of inorganic phosphorus (phosphate) in the specimen.

4. Qualifying circumstances

CPT 84100 is used when clinicians order a test to evaluate the level of inorganic phosphorus (phosphate) in a patient specimen. This test is not limited to diagnosing a specific condition but can help diagnose various conditions associated with high or low phosphate levels. High phosphate levels can cause low calcium blood levels, resulting in seizures, low blood pressure, and soft tissue calcification. Low blood phosphate levels can cause muscle weakness, breakdown of red blood cells, reduced bone growth, and potentially death.

5. When to use CPT code 84100

CPT code 84100 should be used when a lab analyst performs a test to evaluate the level of inorganic phosphorus (phosphate) in a patient specimen, such as serum. This code is not used for testing phosphate in urine; for that, CPT code 84105 should be used instead.

6. Documentation requirements

To support a claim for CPT 84100, the following documentation is required:

• Patient’s specimen type (e.g., serum)
• Date and time of the test
• Results of the test indicating the level of inorganic phosphorus (phosphate)
• Signature of the lab analyst performing the test

7. Billing guidelines

When billing for CPT 84100, ensure that the test is performed by a lab analyst on a patient specimen, such as serum. If the test is part of a panel, do not separately report CPT 84100; instead, report the appropriate panel code. It is important to note that some payers may separately reimburse for specimen collection using a code such as 36415.

8. Historical information

CPT 84100 was added to the Current Procedural Terminology system on January 1, 1990. The code underwent a change on January 1, 2010, but no additional information about the change is available.

9. Examples

1. A lab analyst performs a test on a patient’s serum specimen to evaluate the level of inorganic phosphorus (phosphate).
2. A clinician orders a test to assess the phosphate levels in a patient’s serum to help diagnose a condition associated with abnormal phosphate levels.
3. A lab analyst compares the color change in a tested sample solution to a standard solution using colorimetry to determine the level of inorganic phosphorus (phosphate) in a patient’s specimen.
4. A patient’s serum specimen is tested for inorganic phosphorus (phosphate) levels to monitor their response to a specific treatment.
5. A lab analyst evaluates the level of inorganic phosphorus (phosphate) in a patient’s serum specimen to assess their overall metabolic health.
6. A clinician orders a test to measure the inorganic phosphorus (phosphate) levels in a patient’s serum as part of a comprehensive metabolic panel.
7. A lab analyst performs a test on a patient’s serum specimen to investigate the cause of abnormal calcium levels, which may be related to phosphate imbalance.
8. A clinician orders a test to assess the inorganic phosphorus (phosphate) levels in a patient’s serum to evaluate their bone health.
9. A lab analyst compares the color change in a tested sample solution to a standard solution using colorimetry to determine the inorganic phosphorus (phosphate) levels in a patient’s serum specimen.
10. A patient’s serum specimen is tested for inorganic phosphorus (phosphate) levels to monitor their nutritional status.