Summary & Overview
CPT 84105: Urine Inorganic Phosphate Measurement
CPT code 84105 designates a laboratory assay that measures inorganic phosphate in a urine specimen. This biochemical test is used in clinical evaluation of phosphate homeostasis, renal tubular function, and certain metabolic or endocrine disorders. As a commonly ordered urine chemistry, it influences diagnostic workflows and laboratory billing nationwide.
Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise clinical context for when the test is used, typical sites of service, and an overview of billing considerations. The publication presents national benchmarks where available, common billing modifiers, and payer coverage patterns to aid billing, coding, and revenue cycle professionals in aligning claims with clinical documentation and payer policies.
The report also summarizes relevant policy updates affecting laboratory services, highlights scenarios that commonly trigger claim review, and points to related laboratory procedures for clinical correlation. Data not available in the input is clearly indicated where applicable.
Billing Code Overview
CPT code 84105 describes a laboratory assay performed by a lab analyst to measure the concentration of inorganic phosphate (phosphorus not bound in biological compounds) in a urine specimen. This test quantifies urinary phosphate levels to evaluate disorders of phosphate handling, renal function, or metabolic bone disease.
Service Type: Clinical laboratory test — urine phosphate measurement
Typical Site of Service: Clinical laboratory or hospital laboratory, outpatient collection sites
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Clinical & Coding Specifications
Clinical Context
A 52-year-old patient with a history of recurrent nephrolithiasis and episodes of unexplained hypophosphatemia presents to the outpatient laboratory for metabolic evaluation. The clinician orders a random or timed urine phosphorus (phosphate) assay to quantify urinary inorganic phosphorus excretion as part of an evaluation for renal phosphate wasting, hyperparathyroidism, or metabolic bone disease. The specimen is collected as a spot urine or a 24-hour urine depending on the clinical question. The laboratory analyst performs the test using a validated automated chemistry analyzer to measure inorganic (non-organic) phosphate concentration in the urine. Results are reported in mg/dL (spot) or mg/24 hr (timed) and interpreted alongside serum phosphate, creatinine, and other metabolic studies. Typical sites of service include outpatient laboratory collection centers, hospital outpatient labs, and physician office laboratories with CLIA-waived or moderate-complexity testing capabilities. Turnaround time is generally same-day to 48 hours depending on batching and confirmatory procedures.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation portion of a test if applicable (rare for automated urine chemistry). |
TC |