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Official Description

Oxalate

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 83945 refers to a laboratory test that measures the levels of oxalate in the blood or urine. Oxalate is a compound that is derived from oxalic acid, which is a naturally occurring substance found in various foods and produced by the body. In the context of this test, oxalate is significant because it can bind with calcium and magnesium to form oxalate compounds, which may have implications for kidney function and the formation of kidney stones. The measurement of oxalate levels is important for diagnosing and managing conditions related to oxalate metabolism, such as primary hyperoxaluria or calcium oxalate kidney stones. The test involves obtaining a blood sample through venipuncture, which is a procedure where a needle is inserted into a vein to collect blood. This blood sample is then analyzed using an enzymatic assay, a method that utilizes enzymes to quantify the oxalate concentration. Additionally, urine is collected over a 24-hour period, and the oxalate levels in the urine are measured using quantitative spectrometry, a technique that allows for precise measurement of the oxalate concentration in the urine. This comprehensive approach ensures accurate assessment of oxalate levels, aiding in the diagnosis and management of related health conditions.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The oxalate test (CPT® Code 83945) is indicated for various clinical scenarios where monitoring oxalate levels is essential. The following conditions may warrant this test:

  • Primary Hyperoxaluria A genetic disorder characterized by excessive production of oxalate, leading to kidney stone formation and potential renal failure.
  • Calcium Oxalate Kidney Stones Patients with a history of calcium oxalate stones may require this test to evaluate oxalate levels and guide dietary or therapeutic interventions.
  • Renal Function Assessment In patients with compromised kidney function, measuring oxalate levels can help assess the severity of the condition and the risk of stone formation.
  • Monitoring Treatment Efficacy For patients undergoing treatment for conditions associated with elevated oxalate levels, this test can help evaluate the effectiveness of dietary modifications or pharmacological therapies.

2. Procedure

The procedure for obtaining the oxalate test involves several key steps to ensure accurate measurement of oxalate levels in both blood and urine samples. The following procedural steps are outlined:

  • Step 1: Blood Sample Collection A blood sample is obtained through a process known as venipuncture. This involves the insertion of a sterile needle into a vein, typically in the arm, to draw a specific volume of blood. The collected blood is then placed in a suitable container for laboratory analysis. It is important that this step is performed by a trained healthcare professional to minimize discomfort and ensure the integrity of the sample.
  • Step 2: Blood Sample Analysis The blood sample is analyzed using an enzymatic assay. This method employs specific enzymes that react with oxalate in the sample, allowing for the quantification of oxalate levels. The enzymatic assay is a reliable technique that provides accurate results, which are essential for diagnosing conditions related to oxalate metabolism.
  • Step 3: Urine Collection A 24-hour urine collection is required for the oxalate test. Patients are instructed to collect all urine produced over a 24-hour period in a designated container. This comprehensive collection ensures that the urine sample reflects the total oxalate excretion over a full day, which is critical for accurate assessment.
  • Step 4: Urine Sample Analysis The collected urine is then tested using quantitative spectrometry. This analytical technique measures the concentration of oxalate in the urine sample, providing valuable information about the patient's oxalate excretion levels. The results from both the blood and urine analyses are then compiled to give a complete picture of the patient's oxalate status.

3. Post-Procedure

After the oxalate test is completed, there are no specific post-procedure care requirements for patients. However, it is important for patients to follow any instructions provided by their healthcare provider regarding hydration and dietary modifications, especially if they are being evaluated for conditions related to oxalate metabolism. The results of the test will typically be reviewed by the healthcare provider, who will discuss the findings with the patient and determine any necessary follow-up actions or treatments based on the oxalate levels measured in both blood and urine samples.

Short Descr ASSAY OF OXALATE
Medium Descr ASSAY OF OXALATE
Long Descr Oxalate
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 2
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
GY Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit
GA Waiver of liability statement issued as required by payer policy, individual case
76 Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
77 Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
91 Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient.
GW Service not related to the hospice patient's terminal condition
Q3 Live kidney donor surgery and related services
XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service
Date
Action
Notes
2013-01-01 Changed Medium Descriptor changed.
Pre-1990 Added Code added.
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