According to ICD-10-CM Guidelines, I11A.0 (Resistant hypertension) is used to indicate hypertension that remains uncontrolled despite the use of multiple antihypertensive medications. Resistant hypertension is coded to highlight the severity of the patient's condition and the difficulty in managing their blood pressure.
This code is added as a secondary code to reflect the persistent elevation of blood pressure despite medication.
A: I10 (Essential hypertension) is a general code for primary hypertension but does not specify resistance to treatment.
B: A code from category I27 is related to pulmonary heart diseases, not directly related to hypertension management issues.
D: A code from category I16 (Hypertensive crisis) is used for hypertensive emergencies or urgencies, which are acute episodes, not persistent uncontrolled hypertension despite treatment.
Thus, the correct answer is C. I11A.0, Resistant hypertension.