CPT® Code 83735 is used to report the measurement of magnesium levels in a patient’s serum or plasma. Magnesium testing is a routine laboratory assay that helps clinicians assess electrolyte balance, kidney function, cardiovascular health, and metabolic status. Monitoring magnesium is especially important for patients with chronic illnesses, those on diuretics, individuals with cardiac arrhythmias, or patients receiving parenteral nutrition.
This code reflects a laboratory test performed using validated chemical or enzymatic methods, ensuring accurate results that inform clinical decision-making. CPT 83735 is a standalone code for the magnesium test itself; interpretation and follow-up are reported separately as part of the patient’s evaluation.
Key facts about CPT Code 83735
Service type: Clinical laboratory test
Provider type: Physicians, laboratories, and qualified healthcare professionals
Medical services included: Yes—measurement of magnesium concentration in serum or plasma
Specimen type: Serum or plasma
Common clinical indications:
- Evaluation of electrolyte imbalances
- Monitoring patients with renal disease or chronic kidney injury
- Assessment of cardiac arrhythmias or neuromuscular disorders
- Monitoring magnesium supplementation or deficiency treatment
- Supporting diagnosis of metabolic or endocrine disorders
When to use CPT Code 83735
CPT 83735 is appropriate when:
- A serum or plasma sample is collected from a patient
- Magnesium testing is medically necessary for diagnosis, monitoring, or follow-up
- Results will inform treatment decisions, such as supplementation or medication adjustment
Examples include checking magnesium levels in a patient with persistent fatigue, muscle weakness, or cardiac irregularities, or monitoring a patient receiving diuretics that may alter magnesium balance.
Documentation requirements
To properly support CPT 83735 billing, documentation should include:
- Patient identifiers and date of specimen collection
- Sample type (serum or plasma)
- Medical indication for testing
- Method used (chemical, enzymatic, or automated analysis)
- Results and any follow-up recommendations or interventions
Accurate documentation ensures proper reimbursement, compliance, and integration with the patient’s longitudinal health record.
Reimbursement and coding considerations
Most commercial payers, Medicare, and Medicaid cover CPT 83735 when medically necessary. Important considerations:
- This code is lab-only and does not include interpretation or follow-up care
- It may be combined with other electrolyte or metabolic panels if clinically appropriate
- Modifier usage may be required if multiple tests are performed on the same specimen
Always confirm payer-specific policies for lab testing and bundling.
How OptiMantra supports lab management and coding
OptiMantra’s integrated EMR and practice management platform streamlines laboratory workflows, ensuring accurate testing, documentation, and billing for CPT 83735.
With OptiMantra, providers can:
- Automatically link lab orders to the patient’s chart for longitudinal tracking
- Document indications and follow-up recommendations directly in the EMR
- Support accurate coding and clean claim submission.
- Integrate lab results with overall patient care plans for coordinated treatment
By centralizing lab management, OptiMantra helps practices maintain compliance, improve patient care, and ensure proper reimbursement for laboratory services like magnesium testing.
Try OptiMantra for free here!
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