The Qualifier None is identified by letter "Z" and occupies the 6th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to CG421Z
Nonimag Nucl Med Uptake Thyroid Gland w Technetium 99m
Nonimag Nucl Med Uptake of Thyroid Gland using Iodine 131
Nonimag Nucl Med Uptake of Thyroid Gland using Iodine 123
Nonimag Nucl Med Uptake Thyroid Gland w Oth Radionuclide