When normal kidneys fail

When normal kidneys fail

Dialysis compared with normal kidneys

n Many patients think that dialysis duplicates or approaches normal kidney function and that, once dialysis starts, normal or near-normal kidney function is returned. Sadly, this is not so …

n Dialysis does a good job

But …

n Current dialysis falls far, far short of ‘optimum’ kidney function

n The following comparisons may surprise many of you, but they are true …

n End Stage Renal Failure (pre-dialysis) ~ 8 ml/min

n 4x3 HD (mean Kt/V of 1.3, 3 times/ wk) = 13 ml/min

n Nocturnal HD 6 nights/wk (Qd = 300ml/min) = 50 ml/min

n 2 normal kidneys = 100ml/min

As you can see, even ‘optimal’ dialysis falls far short of two normal kidneys.

So … what makes normal kidneys so much better?

n What is normal kidney function?

n What do normal kidneys do?

Knowing this will help you understand how dialysis works and how the various ‘dialysis options’ might differ

n Normal kidneys work solidly and consistently, 24 hrs/day, 7 days/week.

n The way normal kidneys work is well shown at:

http://nephron.com/htkw.htm

Yet …

n When people with chronic kidney failure start dialysis, dialysis is most commonly prescribed for just 12 hrs/week

n For the other 156 hours of the week, it’s …

…..……..‘Sorry, but we’re out to lunch’!!

Normal kidneys

n Work non-stop 24 hrs/day, 7 days/wk.

n Work consistently and relentlessly

n Have an extraordinary workload and …

n Do so much more than most people know

n Without kidneys, there is no survival … unless dialysis or transplantation is undertaken

n The anatomy and structure of the normal kidney is well described at

http://www.mythos.com/webmd/Content.aspx?P=KIDNEY

n The functions of the normal kidney are well described at

http://vanderbiltowc.wellsource.com/dh/content.asp?ID=1077

Normal kidneys do many wonderful things. They:

n Control the excretion of chemical wastes

n Regulate body salt and body fluid

n Control the volume of both the blood and tissue fluids

n Control the blood pressure through renin and aldosterone production

n Produce erythropoeitin and activate vitamin D from its inactive form

n Control blood and bone calcium and phosphate levels

n Regulate bone strength through controlling vitamin D

n Control red blood cell production through erythropoeitin

Chronic kidney failure

Occurs when:

n The anatomy and structure is damaged/lost

n All or most of the normal functions are lost

When kidneys fail

The following two tables first compare normal kidneys to kidney failure then show the symptoms that result from kidney failure. Read the left side of each table and compare with the right side.

Normal Function n Excrete chemical wastes n Regulate body salt and body fluid n Control blood pressure n Control body calcium and phosphate and regulate bone strength through vitamin D n Control red blood cell production through erythropoeitin	Kidney failure n Wastes build up and ‘poison’ the body n Fluid retention occurs in the ankles and lungs n Blood pressure rises n Bone strength is slowly lost and blood vessels are damaged by calcium deposits n Blood production falls, anaemia develops with less oxygen transport
→ →	→
Kidney failure n Wastes build up and ‘poison’ the body n Fluid retention occurs in the ankles and lungs n Blood pressure rises n Bone strength is slowly lost and blood vessels are damaged by calcium deposits n Blood production falls, anaemia develops with less oxygen transport	Symptoms n Cramps, itch, mental slowness, irritability n Swollen legs and shortness of breath n Headaches, dizziness n Bone aches and pains and deteriorating blood circulation to the feet, legs and heart n Shortness of breath, angina (chest pains), lethargy and fatigue

How dialysis works

It may be useful to understand how dialysis works and I strongly recommend this easy guide to understanding dialysis …see HOW DIALYSIS WORKS