Summary & Overview
CPT 83528: Intrinsic Factor Measurement, Serum Assay
CPT code 83528 denotes a laboratory assay that measures intrinsic factor, a gastric protein essential for vitamin B12 absorption. This test has clinical importance for diagnosing pernicious anemia and other causes of B12 deficiency and can influence hematology and neurology care pathways. Nationally, intrinsic factor measurement is a discrete laboratory service used in diagnostic workups when B12 malabsorption is suspected.
Key payers addressed in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Coverage and coding policies for this type of laboratory diagnostic vary by payer and setting.
Readers will find a concise explanation of the clinical context for CPT code 83528, the typical site and service type, and an outline of what to expect in payer coverage and benchmarking discussions. This publication also summarizes common modifiers and service-line considerations where available and highlights areas where policy updates or payer-specific rules commonly affect billing and reimbursement for intrinsic factor testing. Data not available in the input will be noted as such in detailed sections.
Billing Code Overview
CPT code 83528 describes a laboratory measurement of intrinsic factor, typically performed on a serum specimen. Intrinsic factor is a gastric glycoprotein required for absorption of vitamin B12; measurement can support evaluation of causes of vitamin B12 deficiency and related hematologic or neurologic conditions.
Service type: Laboratory diagnostic test
Typical site of service: Clinical laboratory or hospital outpatient laboratory
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient presents to primary care with progressive fatigue, paresthesia in the hands and feet, pallor, and a history of intermittent gastroesophageal reflux disease. Initial CBC demonstrates macrocytic anemia with elevated mean corpuscular volume. The clinician orders serum vitamin B12 and intrinsic factor antibody testing. A phlebotomy is performed and a serum specimen is sent to the clinical laboratory. The laboratory analyst performs 83528 to measure intrinsic factor (often measured as intrinsic factor antibodies or intrinsic factor assay depending on the laboratory method) to evaluate for pernicious anemia and impaired vitamin B12 absorption. Results are reported to the ordering provider; positive intrinsic factor testing supports autoimmune-mediated malabsorption of vitamin B12 and influences downstream management, including referral to hematology or gastroenterology for further evaluation and B12 replacement planning.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
11 | Normal or routine service | Applied when this is the primary lab test performed without unusual circumstances |
26 |