The 2020 International Society of Hypertension Global Hypertension Practice Guidelines defines high blood pressure as systolic blood pressure (SBP) ≥140 mm Hg and/or a diastolic blood pressure (DBP) ≥90 mm Hg. The following is recommended:
-Consider monotherapy in low risk grade 1 hypertension or in very old (greater than or equal to 80 years of age) or frailer patients.
-Consider an Angiotensin-converting enzyme (ACE) inhibitor or Angiotensin receptor blocker (ARB) and a thiazide-like diuretic in post-stroke, very elderly, incipient heart failure, or calcium channel blocker (CCB) intolerance.
-Consider an ACE-inhibitor or an ARB and a Dihydropyridine calcium channel blockers (DHP-CCB) OR a DHP-CCB and thiazide-like diuretic in black patients.
-Caution with spironolactone or other potassium-sparing diuretics when estimated GFR<45 mL/min/1.73m^2 OR K+ >4.5 mmol/L.
For patients with hypertension and Chronic Kidney Disease (CKD), the guideline recommends that blood pressure should be lowered if ≥140/90 mmHg and treated to a target <130/80 mmHg (<140/80 in elderly patients). RAS-inhibitors are first-line drugs as they reduce albuminuria in addition to blood pressure control. CCBs and diuretics (loop-diuretics if eGFR <30 ml/min/1.73m^2) can be added if needed, and eGFR, microalbuminuria and blood electrolytes should be monitored. 
The 2018 AHA/ACC Hypertension Guideline Update states that to prevent and treat hypertension, blood pressure should first
be categorized as normal (less than 120 mm Hg systolic and less than 80 mm Hg diastolic), elevated (120 to 129 mm Hg systolic and less than 80 mm Hg diastolic), stage 1 hypertension (130 to139 mm Hg systolic or 80 to 89 mm Hg diastolic), or stage 2 hypertension (at least 140 mm Hg systolic or at least 90 mm Hg diastolic). A target blood pressure of less than 130/80 mm Hg is recommended for adults with confirmed hypertension and cardiovascular disease (CVD) or a 10-year atherosclerotic CVD risk of 10% or more. A target of less than 130/80 mm Hg may be reasonable for adults with confirmed hypertension but no additional markers of increased CVD risk. The blood pressure target for adults with hypertension and CKD should be less than 130/80 mm Hg.
First-line agents include thiazide diuretics, CCB's, and ACE-inhibitors or ARBs. Initiation of blood pressure-lowering
therapy with two first-line agents of different classes (as separate agents or in a fixed-dose combination) is recommended for adults with stage 2 hypertension and an average blood pressure more than 20/10 mm Hg above their target. Therapy with a single agent is reasonable in adults with stage 1 hypertension and target blood pressure less than 130/80 mm Hg. 
According to the JNC 8 Guidelines for the Management of Hypertension in Adults (2014), persons 18 years or older with CKD or diabetes mellitus, the treatment threshold should be 140/90 mm Hg and target blood pressures should be <140/90 mm Hg. Initial antihypertensive treatment should include a thiazide diuretic, calcium channel blocker, ACE inhibitor, or ARB in the general nonblack population or a thiazide diuretic or calcium channel blocker in the general black population. 
The National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI) not only endorses the use of diuretics to treat hypertension in most patients with CKD but also recommends switching from thiazide to loop diuretics when estimated GFR falls below 30 mL/min/1.73 m2. The Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommends that loop diuretics are particularly useful when treating edema and high blood pressure in patients with CKD stage 4–5, in addition or as an alternative to thiazide diuretics. 
Thiazide diuretics reduce blood pressure by causing natriuresis, thereby reducing extracellular volume, venous return, and cardiac output. In CKD, where extracellular fluid (ECF) volume is expanded and there is an impaired natriuretic response, a loop diuretic may be needed to achieve the level of diuresis required to reduce ECF volume and decrease blood pressure.
While some studies state that thiazide diuretics are not effective when the glomerular filtration rate (GFR) is below 30 ml/min/1.73 m^2, differences in potency, duration of action, and off-target effects could have blood pressure-lowering benefits in patients with moderate-to-advanced CKD. The mechanism responsible for improved blood pressure control in patients with CKD could result from a mild diuresis produced by the more potent and/or longer-acting thiazide agents, or more likely, a result of the off-target effects causing vasodilatation.
Since the 1970's, there have been 14 studies, including 5 randomized controlled trials, that have assessed the antihypertensive and diuretic effects of thiazides in CKD. Overall, it was found that thiazide-type diuretics, alone and in combination with loop agents, were effective as antihypertensive and diuretic agents in patients with advanced CKD, and the most dramatic benefit on sodium excretion and blood pressure occurred when a thiazide-type diuretic was added to a loop agent.
Studies showed that the blood pressure lowering effect of thiazide diuretics when prescribed as mono-therapy for primary hypertension did not have significant differences in the extent of blood pressure lowering among the different agents. However, there did seem to be a benefit favoring chlorthalidone when assessing 24-hour ambulatory blood pressure (ABPM) monitoring.
Studies showed that chlorthalidone was roughly three times as potent as hydrochlorothiazide (HCTZ), though at maximum clinical doses of each drug, the reductions in systolic blood pressure were similar. It was also suggested that chlorthalidone may be superior to HCTZ for regression of left ventricular hypertrophy and reduction of cardiovascular events. Head-to-head studies comparing chlorthalidone and HCTZ showed trends favoring chlorthalidone as a more effective blood pressure lowering agent, but statistical significance in this regard was not consistently demonstrated.
The most common adverse effects observed in hypertension trials include hyponatremia, hypokalemia, hypomagnesemia, hyper-uricemia, hyperlipidemia, hyperglycemia, new-onset diabetes mellitus, and stimulation of the renin–angiotensin–aldosterone system (RAAS). Patients should be closely monitored for volume depletion, hyponatremia, hypokalemia, hypercalcemia, and acute kidney injury. Although, the risk of hypokalemia may be decreased when diuretics are used in combination with ACE-inhibitors or ARBs. [4, 5, 6, 7]