D ialysis and D iet

The double act that keeps you healthy without kidneys  

Our kidneys are pretty remarkable organs. Most people know about their main role, but infact they perform a double act. Act One is waste removal, where they filter excess mineralsand the wastes and toxins that build up in our blood after we have digested the food we eatand drink. Then they combine all this waste with any fluid (water) we don’t need into urineand pass it to the bladder for disposal. Removing the wastes and toxins keeps us healthy;removing the extra fluid helps control or blood pressure.

Act Two is more a behind-the–scenes performance, where they regulate the mix of

electrolytes (sodium, potassium, chloride, and bicarbonate) for a healthy heart and centralnervous system; and the calcium and phosphate levels in our bodies in conjunction withour parathyroid glands to keep our bones strong and our blood haemoglobin levels healthy.

With all this going on, replacing our kidneys when they fail is the original hard act to follow.

But, fortunately we live in a time of medical and biotech wonder that has done just that,also as double act:

  Act One: Dialysis to remove waste and control excess fluid

  Act Two: Diet to minimise salt and potassium and phosphate-rich foods;supplements to manage our calcium, phosphate, red blood cell, iron and ferritinlevels.

 Together they form a new double act that keeps us healthy long after our kidneys have leftthe building.

 Act One: Dialysis

Dialysis removes waste and controls fluid by passing our blood through a dialyser thatfilters out most wastes and excess water and returns clean blood back to our body. Thereare two ways to dialyse: Haemodialysis (HD) and Peritoneal Dialysis (PD).

Haemodialysis

Haemodialysis is done by machine. Two needles are inserted into an enlarged vein in yourforearm, called a fistula (created surgically a few months before you begin dialysis). Bloodis pumped from your arm via the first needle and tubing to a dialyser on the dialysismachine. The dialyser filters the blood and extracts wastes and water, which aredischarged into a drain. The amount of water to be removed can be varied, depending onhow the machine is set up. The freshly cleaned blood is returned to the body via the secondneedle.

 This is done continuously for as long as the machine pump operates. At any one time onlyabout a cupful of blood is outside the body. During each session, the equivalent of all theblood in your body will be filtered several times. The more blood that passes through thedialyser, the more effective the dialysis, so the keys to good dialysis are the speed of thepump (typically 300 – 350 mL/min), the size of the needles (the larger the better) and thetime spent on the machine (most people dialyse for 3-4 hours each time, about three timesper week).

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 Briefing # 4 

 

Peritoneal Dialysis

Peritoneal Dialysis uses a natural membrane inside your abdomen to remove wasteproducts. A small, soft plastic tube is sewn into your solar plexus (a 15-30 min surgicalprocedure). The tube is used to add special dialysis fluid into abdominal cavity. Wasteproducts are absorbed by the dialysis fluid, which is then drained out again. Depending onthe type of PD you choose, this can be done either by hand four times a day (calledContinuous Ambulatory Peritoneal Dialysis – CAPD) by a machine overnight (calledAutomated Peritoneal Dialysis – APD).

 Act Two: Diet

 The bad news is that once we lose kidney function, just about everything we eat has thepotential to kick us off the straight and narrow. Our fluids and electrolytes are finelybalanced. Any one mineral or chemical has the potential not just to cause its own problems,but to set a clutch of other dominoes falling with it.

 Take salt: alone, too much makes us THIRSTY. VERY THIRSTY; so we drink too much andwith nowhere to go that lovely fluid pools around our body; our blood pressure goesthrough the roof; fluid sitting on our lungs makes it hard to breathe; ankles and legs swell;and on it goes. Sadly there is no pill to neutralise a salt overdose. We have to programourselves and others not to cook with salt and to remember to tell people not to add salt to your food. We soon come to learn that ideally, we should only drink about a litre a day.

It’s the same with potassium, which controls nerve and muscle function. In particular itkeeps our heart in rhythm. High levels can cause nausea, weakness, numbness or tingling,slow pulse, irregular heartbeat and heart failure. Potassium is in nearly everything, so weshouldn’t eat too much  meat, poultry or fish, apricots, avocado, bananas, melons, kiwi fruit,lima beans, milk and cheese, oranges and orange juice, potatoes, prunes, spinach,tomatoes, even vegetable juice.

Phosphate packs a double whammy. Too much results in long term problems like weakand brittle bones, and calcium deposits throughout the body. But the immediate impact isalso dire: Olympic level skin itching, joint pain and eye irritation and sometimes unstableheart rhythms and even heart failure. Again, phosphate is in nearly every food, butespecially so in foods like pastries, whole grain bread, cola drinks, coffee, chocolate, dairyproducts, mayonnaise, margarine, egg yolks, peas, lentils, nuts, puddings and gravies,processed meats and too many more. You can’t eliminate phosphate from your meals, but you can stay away from or minimise foods with lots in it.

You can also control phosphate levels with phosphate binders (like Caltrate, Renagel,Alutabs or Fosrenol). These work pretty simply: you take at least one just before you havefood or drink. The pill sits in your stomach and dissolves into a paste. As the phosphate-rich food arrives, the phosphate binds with the paste. The bound molecules are then

carried through the gut, into the bowel and out into the cold hard world.

At first glance, this new diet routine may seem onerous – and it can be if you let it take over. The key is moderation, not abstinence. It will take some time to find the combination offoods that work for you (most of the time your body will tell you when you have strayed toofar). But you will find it. The right diet does require some self-control, but not an iron will.

Supplements like calcium, Calcitriol, Erythropoietin or Darbepoetin alfa, iron, and ferritinalso form a key part of most BigD-er’s lives, keeping our bones strong and our blood redand healthy. With supplements we need less self-control to stay well; their use is usuallymanaged by our kidney specialist, and our only role is to take them as prescribed.

Over the years you’ve come to know and love many quality double acts: Oliver and Hardy,Abbot and Costello, Pete and Dud, Jekyll and Hyde, but none so life changing as Dialysisand Diet the latest duo in your life. Get to know them!

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