REN and obstructive sleep apnea syndrome: ARR: aldosterone renin ratio; PRA: plasma renin activity; S: serum; eGFR: estimated glomerular filtration rate; HTN: hypertension; SBP: systolic blood pressure; DBP: diastolic blood pressure; A:C: albumin:creatinine; ECHO EF%: echocardiography ejection fraction%; OSA: obstructive sleep apnea; AHI: apnoea hypopnea index; IHD: ischemic heart disease; RH: resistant hypertension