Blog entry by Meguid El Nahas
A Myth is a widely held but false belief or idea.
Nephrology is full of Myths that are peddled and believed without valid supporting evidence; some are based on animal experimentation without supporting evidence in man. Some are simply unsubstantiated and unvalidated but repeated often enough for all...to beleive!?
Here is a list of 10 such Myths:
1. CKD progresses relentlessly....FALSE, many CKD patients stages 1-3a, seldom progress in a meaningful fashion...
some stay at CKD4-5 for months without progressing!
2. CKD progression is linear....FALSE, CKD progression has many patterns with non-linear progression in some and even regression in some...
3. Renal Hyperfiltration accelerates CKD...FALSE, no evidence from animal or human data; in animals hyperfiltration per se is irrelevant but glomerular hypertension is more important, but may all be related to systemic blood pressure levels and its transmission to the glomeruli (see Bidani and Griffin: https://www.ncbi.nlm.nih.gov/pubmed/23132368)
4. Proteinuria worsens the progression of CKD....FALSE, no evidence for that... and many examples were proteinuria/albuminuria is reduced and progression worsens...example: ONTARGET were albuminuria comes down with dual RAAS blockade and CKD progression worsens (https://www.ncbi.nlm.nih.gov/pubmed/18378520)...
also treatment with Aliskiren decrease proteinuria but has no effect on CKD progression (https://www.ncbi.nlm.nih.gov/pubmed/28598381)!
5. Uric Acid is nephrotoxic...FALSE, no clinical evidence...(https://www.ncbi.nlm.nih.gov/pubmed/27339448), and reduction by allopurinol is confounded by the drug hypotensive effect!
6. ACE inhibition slows the progression of CKD beyond BP control...FALSE, as meta-analysis of data do not support a specific Reno- or Cardio- protective effect of RAAS inhibition in CKD (see previous Blogs).
7. RAAS beneficial in Diabetic Kidney Disease (DKD) independently of BP lowering...FALSE, no evidence that this effect is independent of a better BP lowering as 24h BP was never measured and GFR itself never measured...
8. Low BP slows CKD Progression...FALSE, most studies addressing this issue failed to show benefit from aggressive BP reduction; ABCD, REIN2, AASK, SPRINT, etc...(See previous Blog on the topic). In fact, there is anecdotal evidence that raising BP may delay ESRD in advanced CKD...https://www.ncbi.nlm.nih.gov/pubmed/22135795
9. Lipids are nephrotoxic and may accelerate CKD progression (https://www.ncbi.nlm.nih.gov/pubmed/6128601)...FALSE, as lipid lowering (SHARP study) had no impact on CKD progression...(https://www.ncbi.nlm.nih.gov/pubmed/21663949)
10. Glifozins is Cardio- and Reno- protective in Diabetes Mellitus....FALSE, the observed cardioprotection with SGLT2 inhibitors in DM is due to a reduction in BP secondary to the powerful osmotic diuretic effect of these agents...(see previous Blog on the topic)
Sadly, many of these MYTHS are taken for proven FACTS by the Nephrology Community at large without any critical analysis to find the supportive evidence.
They are often based on indirect animal experimentation of little relevance to the clinical situation...or animal experimentation that has not been substantiated in humans. Others are accepted as fact with little scrutiny of the background information or evidence of supporting data...
A critical analysis of these Myths leaves many unanswered questions!
Also knowledge evolves and evidence is challenged leading to challenges to some of these dogmas and myths...