ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview

The International Classification of Diseases, Tenth Revision, Procedure Coding System (ICD-10-PCS) code group CG42 includes procedures performed to assess function by introducing radioactive materials into the thyroid gland. These ICD-10-PCS codes are used for inpatient documentation when a nonimaging nuclear medicine uptake study of thyroid function is performed to quantify radioactive uptake. Accurate coding within the ICD-10-PCS CG42 group is essential for proper inpatient reimbursement, as it captures the procedure performed and supports clinical documentation accuracy.

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Thyroid Gland Nonimaging Nuclear Medicine Uptake Procedure Overview

Procedures in this group involve introduction of radioactive materials into the body to measure thyroid gland function by detecting emitted radiation, targeting the endocrine system. These nonimaging nuclear medicine uptake procedures quantify organ function rather than producing diagnostic images. Accurate coding of these procedures affects inpatient reimbursement because it documents the specific functional test performed on the thyroid gland and supports appropriate case mix assignment.

Code Attributes

Character	ICD-10-PCS Category	Code Group Details
C	Section	Nuclear Medicine
G	Body System	Endocrine System
4	Operation	Nonimaging Nuclear Medicine Uptake
2	Body Part	Thyroid Gland

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ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview

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Thyroid Gland Nonimaging Nuclear Medicine Uptake Procedure Overview

Code Attributes

Character	ICD-10-PCS Category	Code Group Details
C	Section	Nuclear Medicine
G	Body System	Endocrine System
4	Operation	Nonimaging Nuclear Medicine Uptake
2	Body Part	Thyroid Gland

When to Use

Use a code from this group when a radioactive tracer is administered specifically to measure thyroid uptake and quantify gland function without producing diagnostic images. These codes apply when the clinical intent is functional assessment of the thyroid via detection of radioactive emissions.

ICD-10-PCS Codes

4 rows

ICD-10-PCS Code	Description
CG421ZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Technetium 99m (Tc-99m)
CG42FZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Iodine 123 (I-123)
CG42GZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Iodine 131 (I-131)
CG42YZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Other Radionuclide

Typical Clinical Scenarios

An elderly inpatient admitted for new-onset atrial fibrillation with unexplained weight loss and tremor; the clinical team suspects thyrotoxicosis and orders inpatient functional testing to quantify thyroid uptake and differentiate Graves disease from thyroiditis. A nonimaging nuclear medicine uptake study is performed using a radioisotope to measure percentage uptake by the thyroid gland and guide acute medical management. Typical codes: CG42FZZ, CG421ZZ
A scheduled hospital admission for preoperative evaluation of a palpable thyroid nodule where biochemical tests are inconclusive; clinicians perform a nonimaging uptake study to assess focal versus diffuse uptake and help determine need for surgical resection. The procedure measures radionuclide uptake of the thyroid to inform operative planning and risk stratification. Typical codes: CG421ZZ, CG42YZZ
An inpatient with a history of differentiated thyroid cancer presents for postoperative surveillance after thyroidectomy and radioiodine remnant ablation; a quantitative nonimaging uptake assessment is used to evaluate residual thyroid tissue or assess preparation adequacy before therapeutic dosing. The study introduces a radionuclide tracer to quantify residual uptake in the thyroid bed or remnants. Typical codes: CG42GZZ, CG42FZZ

Related Codes

CG4Y-ENDOCRINE-SYSTEM-UPTAKE

ICD-10-PCS Code For Endocrine System: Procedure Code Group Overview

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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When to Use

ICD-10-PCS Codes

4 rows

ICD-10-PCS Code	Description
CG421ZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Technetium 99m (Tc-99m)
CG42FZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Iodine 123 (I-123)
CG42GZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Iodine 131 (I-131)
CG42YZZ	Nonimaging Nuclear Medicine Uptake of Thyroid Gland using Other Radionuclide

Typical Clinical Scenarios

An elderly inpatient admitted for new-onset atrial fibrillation with unexplained weight loss and tremor; the clinical team suspects thyrotoxicosis and orders inpatient functional testing to quantify thyroid uptake and differentiate Graves disease from thyroiditis. A nonimaging nuclear medicine uptake study is performed using a radioisotope to measure percentage uptake by the thyroid gland and guide acute medical management. Typical codes: CG42FZZ, CG421ZZ
A scheduled hospital admission for preoperative evaluation of a palpable thyroid nodule where biochemical tests are inconclusive; clinicians perform a nonimaging uptake study to assess focal versus diffuse uptake and help determine need for surgical resection. The procedure measures radionuclide uptake of the thyroid to inform operative planning and risk stratification. Typical codes: CG421ZZ, CG42YZZ
An inpatient with a history of differentiated thyroid cancer presents for postoperative surveillance after thyroidectomy and radioiodine remnant ablation; a quantitative nonimaging uptake assessment is used to evaluate residual thyroid tissue or assess preparation adequacy before therapeutic dosing. The study introduces a radionuclide tracer to quantify residual uptake in the thyroid bed or remnants. Typical codes: CG42GZZ, CG42FZZ

Related Codes

CG4Y-ENDOCRINE-SYSTEM-UPTAKE

ICD-10-PCS Code For Endocrine System: Procedure Code Group Overview

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview

Sign up for ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview policy alerts

Thyroid Gland Nonimaging Nuclear Medicine Uptake Procedure Overview

Code Attributes

ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview

Sign up for ICD-10-PCS Code For Thyroid Gland: Procedure Code Group Overview policy alerts

Thyroid Gland Nonimaging Nuclear Medicine Uptake Procedure Overview

Code Attributes

When to Use

ICD-10-PCS Codes

Typical Clinical Scenarios

Related Codes

Which procedures are included in ICD-10-PCS code group CG42?

What is the primary purpose of procedures coded in CG42?

Which ICD-10-PCS section and body system apply to CG42 codes?

How does accurate coding in CG42 affect inpatient reimbursement?

How should a coder choose between the individual codes within CG42?

References

When to Use

ICD-10-PCS Codes

Typical Clinical Scenarios

Related Codes

Which procedures are included in ICD-10-PCS code group CG42?

What is the primary purpose of procedures coded in CG42?

Which ICD-10-PCS section and body system apply to CG42 codes?

How does accurate coding in CG42 affect inpatient reimbursement?

How should a coder choose between the individual codes within CG42?

References