The Effect Of Lisinopril On Polycythemia

Inclusion Criteria: * Hemoglobin in Men: \>16.5 g/dL (10.3 mmol/L). * Hemoglobin in Women \>16.0 g/dL (10.0 mmol/L). * BMI 18-40 kg/m2. Exclusion Criteria: * Positive JAK2 gene linked to Polycythemia Vera. * Current smoker or previous heavy smoker (\>15 pack years) who quit less than 12 months prior to enrollment. * Resting SpO₂ ≤ 94% on room air. * Current or recent (within the past 6 months) use of testosterone or androgen supplementation. * Any confounding respiratory or renal disease, including diagnosed or suspected sleep apnea, or stage 3 and up of chronic kidney disease. * Any confounding hematologic disease that may alter hemoglobin level. * Currently treated with ACE inhibitors. * Currently treated with potassium-sparing diuretics. * Currently on SGLT2 or use within 4 weeks prior to screening. * Baseline systolic blood pressure ≤90 mmHg. * Baseline systolic blood pressure \>160 mmHg or diastolic blood pressure \>100 mmHg. * Occupational exposure associated with chronically elevated COHb (auto repair, etc.). * History of anaphylaxis or angioedema. * Pregnant or breastfeeding.