Summary & Overview

CPT 83540: Serum Iron Quantitative Measurement

CPT code 83540 represents a quantitative serum iron assay used to measure circulating iron levels. This laboratory test is a fundamental component of iron-status evaluation and supports diagnosis and monitoring of iron-deficiency anemia, iron overload disorders, and other hematologic or systemic conditions. As a commonly ordered clinical pathology procedure, it plays a role in care pathways across inpatient and outpatient settings and factors into utilization and lab-payment frameworks nationally.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for the test and the typical settings where it is performed. The publication summarizes common billing and service considerations, benchmarking points where available, and any recent policy or coverage themes relevant to laboratory testing reimbursement. The content is intended to inform billing professionals, laboratory managers, and policy analysts about where 83540 fits within clinical workflows and payer coverage landscapes on a national level.

Data not available in the input: associated taxonomies, ICD-10 diagnoses, specific related codes, and payer-specific reimbursement rates.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare83540CPTserum ironlaboratoryclinical pathologyhematologylaboratory billingdiagnostic test

Billing Code Overview

CPT code 83540 measures serum iron to quantify the amount of iron circulating in the bloodstream. The test assesses the iron bound to transferrin and the small fraction of free iron in serum, supporting evaluation of iron deficiency, iron overload, and related hematologic conditions.

Service type: Clinical pathology laboratory test (quantitative serum iron measurement)
Typical site of service: Hospital laboratory, independent clinical laboratory, outpatient phlebotomy or laboratory draw sites

Clinical & Coding Specifications

Clinical Context

A typical patient is a 45-year-old adult presenting to an outpatient clinic with fatigue, pallor, or symptoms suggestive of iron deficiency or iron overload. The clinician orders a serum iron test to quantify circulating iron as part of an iron panel (often with TIBC, ferritin, and transferrin saturation) to evaluate anemia, suspected hemochromatosis, chronic blood loss, or monitoring iron therapy. The patient proceeds to a phlebotomy station in the same ambulatory clinic, hospital outpatient laboratory, or independent clinical laboratory. A trained phlebotomist collects a blood specimen (usually venous), the specimen is sent to the clinical laboratory, and a medical laboratory scientist or technologist performs the assay to measure serum iron concentration. Results are reported to the ordering provider and used to guide diagnosis, further testing, or management, such as additional iron studies, imaging, or referral to hematology.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when reporting only the professional interpretation component if applicable to testing arrangements separated between entities.
`59`	Distinct procedural service	Use when the iron assay is distinct from other services performed at the same visit when linkage edits might bundle them.
`90`	Reference (outside) laboratory	Use when testing is performed by an outside laboratory and billed by the performing lab.
`91`	Repeat clinical diagnostic laboratory test	Use for reporting a repeat measurement on the same day to confirm a result.
`QW`	CLIA waived test	Use if the assay performed is a CLIA-waived methodology and payer requires the modifier to denote waived status.
`TC`	Technical component	Use when reporting only the technical component of the test if separate billing for instrumentation and processing is required.
`52`	Reduced services	Use if the test was partially completed or specimen insufficient and a reduced service is reported per payer rules.
`90`	Reference (outside) laboratory	Use when results are reported by a referring laboratory (duplicate intentionally to emphasize common use).
`59`	Distinct procedural service	Use to indicate distinct service (duplicate intentionally to denote common bundling issues).
`91`	Repeat test (duplicate)	Use when repeated tests are performed to confirm biologic variability (duplicate intentionally).

Taxonomy Code	Specialty	Notes
207R00000X	Pathology & Laboratory Medicine	Clinical laboratory directors and pathologists who oversee testing quality and interpretation.
363L00000X	Clinical Laboratory	Medical laboratory scientists/technologists who perform the assay.
207K00000X	Clinical Pathology	Physicians specializing in clinical pathology ordering or interpreting complex panels.
207LP2900X	Hematology	Hematologists who frequently order and interpret iron studies for anemia and iron overload.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D50.9`	Iron deficiency anemia, unspecified	Primary indication for ordering serum iron to evaluate iron availability and guide iron therapy.
`E83.110`	Hemochromatosis due to HFE gene	Serum iron helps assess iron overload and is part of the evaluation for hereditary hemochromatosis.
`D63.8`	Anemia in other chronic diseases classified elsewhere	Used when chronic inflammatory conditions cause anemia; iron studies help distinguish functional iron deficiency.
`N92.6`	Irregular menstruation, unspecified	In premenopausal women with heavy or irregular menses, serum iron is part of anemia workup.
`K92.2`	Gastrointestinal hemorrhage, unspecified	Acute or chronic GI blood loss warrants iron studies to assess iron depletion.
`E83.10`	Disorder of iron metabolism, unspecified	General code used when iron metabolism abnormality is suspected and testing is needed.
`R53.83`	Other fatigue	Non-specific fatigue often prompts screening labs including serum iron to rule out iron deficiency.
`Z79.01`	Long term (current) use of anticoagulants	Patients on anticoagulants with suspected bleeding may have iron studies to evaluate chronic blood loss.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`83550`	Ferritin; serum	Commonly ordered alongside serum iron to assess iron stores and help distinguish iron deficiency from anemia of chronic disease.
`84466`	Immunoassay for ferritin	Alternative ferritin methodology often run together with iron studies in the laboratory panel.
`84300`	Hemoglobin; quantitative	Performed in the same diagnostic workup for anemia evaluation to correlate iron measurements with hemoglobin status.
`84480`	Thyroid stimulating hormone (TSH)	Often ordered in general fatigue workups to evaluate alternative causes of symptoms alongside iron studies.
`85025`	Complete blood count (CBC) with automated differential	Frequently ordered before or with serum iron to evaluate red cell indices and guide interpretation of iron results.