I think acidosis is an ‘undervalued’ issue in chronic kidney disease (CKD) and renal failure – in part because its effects are commonly subtle and do not cause ‘obvious’ symptoms and in part because it kind of falls last in line for treatment with the other aspects: anaemia and iron management, control of blood pressure (hypertension), lowering of lipid (blood fat) levels, correction of calcium and phosphate imbalance, parathyroid hormone (PTH) suppression with vitamin D and/or calcium mimicking agents like cinacalcet, the management of the accelerated cardiovascular complications of CKD and a host of other seemingly – or in reality - more ‘pressing’ issues.
By the time all those (seemingly) more urgent issues are treated – and the poor patient is already swallowing dozens of pills a day – the treatment of acidosis just seems one step too many, or one additional step too hard.
That is NOT to say that that is a correct approach – just a practical and pragmatic one … especially considering that the only effective means of reversing acidosis (other than by good dialysis) is by using agents like sodium bicarbonate (NaHCO3) = mothers baking soda - but in capsular form. You will understand why NaHCO3 is packed into capsules if ever you tried to swallow a neat spoonful of baking soda!
But … note the word ‘sodium’ or, using kitchen-talk, ‘soda’.
NaHCO3 enforces a sodium load. A sodium load is counterproductive for patients already struggling with the control of their blood pressure, or who have left ventricular (LV) failure or LV overload states (= most patients), or for those who are struggling to control thirst and inter-dialytic weight gain from fluid overload.
For these patients (and it IS the majority), adding yet more sodium to chase and reverse what many think the lesser evil – the effect of chronic acidosis on the metabolism of bone – can be one straw too many.
For those where volume is not an issue (some), or where blood pressure is easily controlled or not an issue (a few), or where the LV is still strong and unthickened by LV hypertrophy … for those, the treatment of any identified acidosis with NaHCO3 is a welcome luxury – and should be embraced.
Well … acidosis is NOT as innocent an issue as some would hope it to be.
The proper terms for the acidosis of CKD is metabolic acidosis and it occurs when the body is either producing too much acid … as can occur with diabetes when it goes haywire and out-of-control and a state called ketoacidosis occurs; when excess lactic acid is made (eg; in long distance runners, or with certain medications taken either as prescribed (eg: metformin in CKD4-5), or by overdosing with substances like salicylates; or when the kidneys are not removing enough acid from the body – as occurs in advanced CKD.
Acidosis is probably more of an issue for patients with CKD than for dialysis patients for GOOD dialysis corrects acidosis well and removes (or buffers) excess acids efficiently. In simple terms, buffering means neutralizing: add alkali to acid and the two cancel each other out, trending to a neutral pH (or a neutral acid:base balance). Note: bad dialysis does not achieve this adequately!
The chronic, persistent, but usually low-grade acidosis that accompanies CKD subtly alters the composition of bone. This is perhaps most evident in children with CKD where the bone is still growing, lengthening and strengthening: perhaps it is in children, especially, that reversal of acidosis should take a more primary place in the treatment matrix.
Chronic metabolic acidosis changes the ionic composition of bone, reducing bone concentrations of apatite, sodium, and potassium. The genes that encourage osteoblast (bone-forming) activity are suppressed while, conversely, osteoclast (bone-reabsorbing) activity is increased. Further, growth hormone, a hormone that helps to encourage bone growth and guides its ordered structure, is also suppressed.
At the end of the day, if acidosis is present and there is room to treat it - sodium loading in mind – then it should be treated.
Shaymon … if you blood pressure is good, your heart healthy, and your volume state manageable yet a chronic metabolic acidotic state has been identified, your physician is on the ball, on the money, and on track.
I agree with him – treat! Sadly, though, such a step is not easily do-able for the majority of patients. You seem, possibly, to be among the lucky few where NaHCO3 can be added in … and to your benefit … as long as volume, BP and other down-sides to NaHCO3 treatment don’t flare their nostrils at you.
Finally, re your question … ‘patchy’ or ‘widespread’?
The effects of a chronic metabolic acidosis are widespread - affecting all bone. The effects of PTH bone disease are not always so. This is a key difference between the two major bone-centric complications of CKD. But again: metabolic acidosis affects all bone.
I hope that this has helped to answer some of your questions.