Hypertension in CKD

Hypertension is both a leading cause and a near-universal consequence of chronic kidney disease. As the kidneys' regulation of sodium, volume, and vasoactive systems fails, blood pressure tends to rise, and elevated pressure in turn accelerates kidney damage, creating a self-reinforcing cycle that links blood-pressure control closely to the rate of CKD progression and to cardiovascular outcomes.

Definition

Hypertension in CKD is sustained elevation of arterial blood pressure occurring in, or caused by, chronic kidney disease, arising largely from impaired sodium and volume handling and activation of the renin-angiotensin-aldosterone and sympathetic nervous systems.

Scope

This topic covers why hypertension and CKD are so tightly intertwined, the mechanisms by which kidney disease raises blood pressure, the bidirectional relationship between pressure and progression, and the major trial evidence that shaped how blood pressure and the renin-angiotensin system are viewed in CKD. It is a reference account of the disease relationship and its evidence base, not individualized treatment guidance.

Core questions

• Why does chronic kidney disease so commonly cause or worsen hypertension?
• How does elevated blood pressure accelerate the progression of CKD?
• What is the role of the renin-angiotensin system in this relationship?
• What does trial evidence show about blood-pressure targets in CKD?

Key concepts

• Sodium and volume retention
• Renin-angiotensin-aldosterone system activation
• Sympathetic nervous system overactivity
• Glomerular hypertension and hyperfiltration
• Bidirectional cause and consequence
• Albuminuria as a pressure-related marker
• RAS blockade in proteinuric CKD

Mechanisms

In CKD the kidney's capacity to excrete sodium falls, so volume expansion raises blood pressure; this is compounded by inappropriate activation of the renin-angiotensin-aldosterone system and by increased sympathetic outflow from the diseased kidneys. Angiotensin II also raises pressure within the glomerulus by constricting the efferent arteriole, and this intraglomerular hypertension promotes proteinuria and progressive injury independently of systemic pressure. Blockade of the renin-angiotensin system lowers both systemic and intraglomerular pressure and reduces albuminuria, which is the mechanistic rationale demonstrated in trials such as RENAAL in diabetic nephropathy; more recently, SGLT2 inhibitors have been shown to slow progression partly through effects on glomerular pressure.

Clinical relevance

Because pressure and kidney injury reinforce each other, blood pressure is one of the most closely monitored parameters in CKD and a central theme of the evidence on slowing progression. This entry explains that relationship and summarizes landmark trials; it characterizes the evidence and does not specify blood-pressure targets, drug choices, or doses for any individual.

Epidemiology

Hypertension is present in the large majority of people with CKD and becomes nearly universal at advanced stages, while CKD is itself one of the commonest identifiable causes of secondary hypertension. The coexistence is strongly associated with faster loss of kidney function and with cardiovascular events.

History

The link between the kidney and blood pressure traces back to Richard Bright's nineteenth-century observations connecting kidney disease and cardiac changes, and to twentieth-century work on the renin-angiotensin system. Trials in the 1990s and 2000s, including the angiotensin-receptor-blocker trial RENAAL, established renin-angiotensin blockade as a means of slowing proteinuric kidney disease, and the SPRINT trial and KDIGO 2021 guideline subsequently reframed thinking on blood-pressure intensity in CKD.

Debates

How low should blood pressure be targeted in CKD?

Intensive blood-pressure lowering in SPRINT reduced cardiovascular events and mortality, including in participants with CKD, but the optimal target balances cardiovascular and kidney benefits against risks such as acute GFR decline, and the question of an ideal target across CKD subgroups remains debated.

Key figures

• Barry M. Brenner
• Hiddo J. L. Heerspink
• Alfred K. Cheung

Seminal works

• brenner-2001-renaal
• sprint-2015
• cheung-2021-kdigo-bp

Frequently asked questions

Is hypertension a cause or a result of chronic kidney disease?

It is both: longstanding hypertension can damage the kidneys, and established kidney disease impairs sodium and volume regulation and activates pressure-raising hormonal systems, so the two commonly drive each other.

Why is the renin-angiotensin system so central to hypertension in CKD?

Angiotensin II raises both systemic blood pressure and pressure inside the glomerulus, and the latter promotes proteinuria and scarring, which is why blocking this system is a recurring theme in the evidence on slowing kidney disease.