CPT code 78099 denotes an unlisted endocrine diagnostic nuclear medicine procedure used when a specific endocrine nuclear medicine code is not available. As an unlisted procedure code, 78099 is applied across a range of specialized imaging studies of the thyroid, parathyroid, or other endocrine organs performed with radiopharmaceuticals. The code matters nationally because it governs how novel or uncommon endocrine nuclear medicine services are reported for billing and reimbursement and often requires additional documentation to justify medical necessity and describe the procedure performed.

Key payers commonly evaluated for coverage and payment patterns include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for endocrine nuclear medicine, guidance on typical sites of service, and discussion of billing implications for an unlisted procedure code. The publication summarizes common documentation expectations, typical modifiers used with unlisted nuclear medicine services, and the types of supplementary information payers often require for adjudication.

This summary prepares clinical billing staff, practice managers, and policy analysts to understand where 78099 fits within nuclear medicine coding, what to expect in payer interactions, and which elements of documentation are frequently necessary when reporting an unlisted endocrine nuclear medicine procedure.