High Blood Pressure causes Kidney Damage


High Blood Pressure (Renal induced hypertension) is a “committed” sign and an essential therapeutic target in chronic kidney disease. But did you know uncontrolled, sustained High Blood Pressure /Hypertension (irrespective of the root cause) itself is a strong risk factor for Chronic Kidney Disease?


High Blood Pressure causes kidney damage | All Things Kidney Official | allthingskidney.com | Kidney Damage


 

This article walks you through the normal blood pressure basics. Then it explains how sustained high BP is a risk factor for kidney disease.

BLOOD PRESSURE BASICS: NORMAL BLOOD PRESSURE

In good health, blood circulates throughout our body through blood vessels with a “pump-system” (Heart) to run the show. This is much like the water pipelines and the pump-set of a house.

The circulating blood exerts some force on the inner lining of blood vessels namely arteries, veins and capillaries while coursing through them. This is what is called, your Blood Pressure.

Normal Blood Pressure clipart allthingskidney.com

As is common knowledge, BP is recorded as two numbers separated by a slash mark (/) & followed by the unit “mm Hg”. For instance, 120/80 mm Hg. These numbers depend on the “relationship” between the blood, blood vessel and heart activity.

When we talk of blood vessels w.r.t. blood pressure, it is imperative that we understand that these vessels differ in how they deal with the blood flowing within.

Arteries carry oxygen rich blood from the heart to the rest of the body. These vessels endure the direct pumping force of the heart and its “ripple” pulse that needs to be powerful so as to reach the extreme end arteries of the body. Hence arteries have the thickest and most elastic wall amongst all blood vessel types.

In any blood pressure reading, the higher number before the slash corresponds to blood pressure put on arteries by the pumping force of the heart, technically called “Systole” (sis-toll). So, the technical name for this upper number in your BP reading is “Systolic Blood Pressure” or Systolic BP.

As per the criteria by the American Heart Association (AHA), in good health, the normal systolic BP for adults at rest should not exceed 120 mm Hg.

 

Veins are less thick-walled and more “spacious from within” than arteries. These vessels bring back oxygen depleted blood from the rest of the body to the heart for an oxygen refill. Every time heart muscles relax after a pump, the heart automatically “sucks in” blood in the veins. This augments the process of veins returning blood to the heart with typically less effort than in case of Arteries. Hence, the lower number in a BP recording corresponds to blood pressure in veins. Heart muscle relaxation is technically called “Diastole” (dye-uh-stole). So, this lower number in your BP reading is called “Diastolic Blood Pressure”.

As per the criteria by the American Heart Association (AHA), in healthy adults, the normal diastolic BP at rest should not exceed 80 mm Hg.

 

As is evident, the pressure on the walls of arteries is a lot higher than the pressure on the walls of the veins. Nature thoughtfully decided to create a buffer zone enabling “gradual transition” from higher pressure in arteries to lower pressure in veins during blood circulation in our body. This is why Capillaries came to exist. These are numerous tiny and delicate vessel branches that connect arteries and veins in necessary junctures. Else, sudden movement of high pressure blood from arteries to veins could permanently damage walls of the vein, normally built to handle relatively lower pressures. Blood pressure monitors do not measure capillary blood pressure.

Now that we understand how normal BP works, let’s proceed to what constitutes high BP/ hypertension is, and how it impacts your kidneys if left untreated.

 

WHEN CAN YOU SAY YOU HAVE HIGH BLOOD PRESSURE

High Blood Pressure illustration | All Things Kidney Official | allthingskidney.com

High blood pressure or Hypertension is a major health problem worldwide. Not just in itself, but because of all the myriad complications that it causes, ranging from Heart attacks, Strokes to Kidney damage & failure, it has dominated research interests and clinical conferences for decades now.

Among such clinical focus groups, two major ones namely the American Heart Association (AHA) and the European Society of Hypertension (ESH) have come up with their definitions for High blood pressure. These definitions and criteria inform day-to-day allopathic clinical practice worldwide.

We are presenting the BP definition basics by AHA and ESH for you below. We strongly recommend you go through these to be able to monitor your own blood pressure accurately.

 


As per the ACC-AHA criteria
CATEGORY OF BLOOD PRESSURESYSTOLIC BLOOD PRESSURE
(Upper number)
DIASTOLIC BLOOD PRESSURE
(Lower number)
NORMAL BPLess than 120Less than 80
ELEVATED BP120-129Less than 80
STAGE 1 HYPERTENSION 130-13980-89
STAGE 2 HYPERTENSION 140-15990-99
STAGE 3 HYPERTENSION Greater than 160Greater than 100

 

 

As per the ESH criteria:
CATEGORY OF BLOOD PRESSURESYSTOLIC BLOOD PRESSURE
(Upper Number)
DIASTOLIC BLOOD PRESSURE
(Lower Number)
OPTIMAL BP Less than 120Less than 80
NORMAL BP 120-12980-84
HIGH NORMAL BP 130-13985-89
GRADE 1 HYPERTENSION 140-15990-99
GRADE 2 HYPERTENSION 169-179100-109
GRADE 3 HYPERTENSION Greater than 180Greater than 110
ISOLATED SYSTOLIC HYPERTENSIONGreater than 140Less than 80

 


 

HIGH BLOOD PRESSURE / HYPERTENSION CAUSES KIDNEY DAMAGE: HOW?

Just like the rest of the body, our kidneys contain an intricate network of fine blood vessels that permeate deep into the kidney tissue all the way to its delicate filtration units – nephrons. This allows them to efficiently process, cleanse & fortify massive amounts of blood in our body at a time.

Seamless “blood-cleansing cycles” within our kidneys requires the blood to cross over from within the vessel carrying it, to the tiny kidney filtration units (nephrons). This happens through numerous delicate “slit-pores” present within the blood-vessel wall & the nephron wall. To prevent damaging these tissue slit-pores, the process must go on in a gentle but effective manner. For this, our body must maintain the BP within the Physiological Blood Pressure Range (110-140/70-90 mm Hg).

If for some reason your blood pressure reading is higher than say, 140/90 mm Hg for a while, it literally robs your blood of all its sophistication! With every heartbeat, blood will be angrily hurtling towards your kidneys with extreme force, kicking-n-shoving the flexible vessel all throughout, punching ruthlessly through the tissue pores mentioned above to enter the nephrons for filtration. These filtration pores will get increasingly battered & damaged every time blood behaves this way.

Moreover, the normally “size-adjusting” blood vessels will adopt a rigid stance against the “rowdy blood” wreaking havoc within it. In due course, vessels will start protesting to this rowdy attitude by becoming thick, stiff. They will refuse to enlarge anymore to make way for sufficient blood.

Damage to the filtration pores immediately signals our immune system to get into a repair-mode. But despite its efforts, persistent high blood pressure hampers the repair process. As a result, pores never recover to the prior healthy versions of themselves. In addition, when blood vessels ultimately stiffen-up, the kidney tissue downstream begins to “starve” for oxygen & other nutrients. This causes our nephrons to starve, shrivel, shrink & ultimately harden to bring about what we call Fibrosis – the hallmark of irreversible kidney damage.

This is exactly why sustained, untreated high blood pressure remains a serious risk factor for kidney disease.

 

TAKE HOME MESSAGE

Keep your BP readings in control. Protect your beautiful beans from abuse!

 

TIPS TO KEEP YOUR BLOOD PRESSURE IN CHECK:

  • Salt contains the mineral Sodium that works to raise our BP. Hence, try to check your salt intake in your diet. Learn more from our Sodium guide in kidney disease here.
  • Manage a healthy weight with diet modifications and/or exercise. Devise a suitable regimen in consultation with your medical team.
  • Adopt stress-management techniques whenever necessary.
  • If you are a known hypertensive, take your BP meds regularly and on time.
  • Monitor your BP religiously at regular intervals.
  • Follow up with your doctors as advised to confirm if any meds need to be revised or replaced.

 

 

END NOTE:

Although this article talks about kidney damage, it is worth noting that since blood goes to all cells of the body, virtually no organ of the body is safe from the torture potential of persistent uncontrolled high blood pressure. Protect your beautiful organs. Give them all the love and care that you can. They absolutely deserve it!

 


 

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