Summary & Overview
CPT 84035: Qualitative Urine Phenylketones Test
CPT code 84035 denotes a qualitative laboratory assay for the presence of phenylketones in urine, a marker used to identify inherited disorders of phenylalanine metabolism such as phenylketonuria. This code matters nationally because newborn screening and diagnostic testing for inborn errors of metabolism are critical for early detection and management, and laboratory coding drives coverage, reimbursement, and clinical reporting workflows. Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will learn the clinical context for CPT code 84035, where the test is typically performed, and what types of operational and billing considerations commonly affect use of this code. The publication summarizes common billing modifiers and highlights where input data are unavailable. It also outlines typical sites of service and the laboratory service type associated with this code. Data not available in the input are noted where applicable.
Billing Code Overview
CPT code 84035 identifies a laboratory procedure that determines the qualitative presence of phenylketones in a patient specimen. This test is used to detect an indicator of an inherited disorder of phenylalanine metabolism, typically performed on urine samples.
Service Type: Laboratory — qualitative urinary metabolite test
Typical Site of Service: Clinical laboratory or outpatient collection site
Clinical & Coding Specifications
Clinical Context
A neonate or infant with suspected phenylketonuria (PKU) is evaluated using a qualitative urine test for phenylketones (84035). Typical workflow: a newborn screening program or pediatric clinic collects a urine specimen during the first days to weeks of life or when developmental concerns arise. The sample is transported to a clinical laboratory where a laboratory analyst performs the qualitative assay to detect phenylketones as an indicator of impaired phenylalanine metabolism. Results are reported to the ordering pediatrician or metabolic specialist. Positive or borderline findings prompt confirmatory quantitative plasma amino acid testing, genetic counseling, and referral to a metabolic/genetics specialist for dietary management and follow-up.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | Procedure performed as billed (no modifier); default reporting | Use when no modifier is applicable and service is reported normally. |
11 | Professional component | Use when reporting only the professional component of a split technical/professional service (if applicable for laboratory oversight reporting abnormalities separate from instrumentation). |