Does N04.21 require prior authorization?

No, N04.21 does not require prior authorization (high confidence). Code is covered without prior authorization.

`N04.21` — Primary membranous nephropathy with nephrotic syndrome

ICD-10-CM

No Prior Auth Required

Code is covered without prior authorization (high confidence)

Medical records must document that the ultrasound was limited to retroperitoneal structures when billing CPT 76770/76775/76776, including images/findings demonstrating limitation to the retroperitoneum.
If the exam was expanded to include organs outside the retroperitoneum, documentation must reflect the expansion and support billing a full or limited abdominal ultrasound (CPT 76700/76705/76706).
Claims and documentation should follow the complementary Local Coverage Determination L34577 and any applicable LCD requirements.
Medical records must document the medical necessity of the serum magnesium test, including the signs, symptoms, and/or diagnosis that prompted the test.

Retroperitoneal ultrasound (CPT 76770, 76775, 76776) is covered when the exam is limited solely to retroperitoneal structures.
A full (complete) or limited abdominal ultrasound (CPT 76700, 76705, 76706) is covered when the exam includes organs or structures outside the retroperitoneum or when primary findings involve non-retroperitoneal structures (e.g., gallbladder, liver, spleen, common bile duct).
ICD-10-CM Codes that Support Medical Necessity — Group 1 (covered diagnoses): D56.1 - Beta thalassemia
ICD-10-CM Codes that Support Medical Necessity — Group 1 (covered diagnoses): D57.02 - Hb-SS disease with splenic sequestration
ICD-10-CM Codes that Support Medical Necessity — Group 1 (covered diagnoses): D57.1 - Sickle-cell disease without crisis
ICD-10-CM Codes that Support Medical Necessity — Group 1 (covered diagnoses): D57.212 - Sickle-cell/Hb-C disease with splenic sequestration

A57198 — Billing and Coding: Serum Magnesium

A55336 — Billing and Coding: Retroperitoneal Ultrasound

A57189 — Billing and Coding: Serum Magnesium

A59186 — Billing and Coding: Magnesium

L34577 — Retroperitoneal Ultrasound

Ask Verity about documentation requirements, denial risks, or coverage in your state.