Summary & Overview
CPT 83735: Measurement of Magnesium in Patient Specimen
CPT code 83735 represents a clinical chemistry laboratory test that measures magnesium concentration in a patient specimen. Magnesium testing is a common diagnostic tool for assessing electrolyte balance, metabolic status, and monitoring patients with conditions that affect magnesium homeostasis. Nationally, magnesium measurement is an important laboratory service across inpatient and outpatient settings because it informs management of cardiac, neuromuscular, and metabolic disorders.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of how CPT code 83735 is classified, where the test is typically performed, and what clinical contexts commonly prompt ordering the test. The publication outlines benchmark considerations, payer coverage patterns, and relevant policy and billing issues for clinical labs and providers who perform or bill for magnesium testing.
The content provides practical reference material for coding teams, lab managers, and revenue cycle staff seeking clarity on the clinical purpose and service setting of CPT code 83735. Data not available in the input are noted where applicable.
Billing Code Overview
CPT code 83735 describes a laboratory test in which a laboratory analyst measures the amount of magnesium in a patient specimen. This is a clinical chemistry service performed on bodily fluids to evaluate a patient’s electrolyte status.
-
Service type: Clinical laboratory test — serum/plasma/whole blood magnesium measurement
-
Typical site of service: Clinical laboratory or hospital laboratory; testing may also be performed in outpatient laboratory facilities or independent reference labs
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A typical adult patient presents to an outpatient clinic or emergency department with symptoms such as generalized weakness, muscle cramps, tremors, tetany, or cardiac arrhythmia. The clinician orders a serum electrolyte panel focused on magnesium to evaluate suspected hypomagnesemia or hypermagnesemia. A phlebotomist collects a peripheral venous blood specimen and sends it to the hospital or commercial laboratory. In the laboratory, a clinical laboratory scientist or medical technologist performs the 83735 quantitative serum magnesium assay using a validated method (e.g., colorimetric or atomic absorption). Results are reviewed by the laboratory analyst and released into the electronic medical record for the ordering clinician to interpret, which may influence intravenous magnesium replacement, oral supplementation, medication adjustments (such as diuretics or proton pump inhibitors), or cardiology monitoring for arrhythmia management. Typical sites of service include hospital inpatient laboratories, outpatient hospital laboratories, reference laboratories, and ambulatory clinic laboratories.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation or analytic review portion provided by a pathologist or laboratory physician separate from the technical assay. |