Blog entry by Meguid El Nahas
'Progressive diabetic nephropathy. How useful is microalbuminuria?
The concept of microalbuminuria has been central to the development of clinical practice and research in the area of diabetic kidney disease (DKD). However, in recent times, the value of a paradigm of DKD based solely on microalbuminuria has been questioned. Although both the absolute level and rate of change of microalbuminuria are linked to the development and progression of DKD, microalbuminuria on its own lacks the necessary sensitivity or specificity to accurately predict kidney outcomes for people with diabetes. The development of microalbumiuria can no longer be viewed as a committed and irreversible stage of DKD, as spontaneous remission is now reported as a common occurrence. In addition, the absence of microalbuminuria or its progression to proteinuria does not signify that an individual patient is safe from a progressive decline in glomerular filtration rate (GFR). Furthermore, although reductions in albuminuria within the microalbuminuric range can be linked to a slower GFR decline in observational studies, this relationship has not been robustly demonstrated in intervention studies. Conclusions regarding the kidney health of individuals with diabetes will continue to be flawed if an inappropriate emphasis is placed on the presence or absence of albuminuria or changes in albuminuria within the microalbuminuric range. This has important implications in terms of undermining the value of microalbuminuria as a surrogate renal end point for intervention trials. There is a need to develop broader models of progressive DKD that include novel pathways and risk markers apart from those related to the traditional 'albuminuric pathway' to renal impairment.Kidney International advance online publication, 9 April 2014; doi:10.1038/ki.2014.98.
This is an extremely timely review highlighting convincingly the limitations of using microalbuminurioa in diabetic nephropathy diagnosis, monitoring and management. It highlights that microalbuminuria lacks both sensitivity and specificity to diagnose renal involvement and their progression in people with diabetes mellitus. This is all the more significant in T2DM.
Once more, it is important to remember that microalbuminuria is a marker of a number of inflammatory and atherosclerotic conditions associated with DM.
Also within the kidneys, microalbuminuria should be thought of as the end results of abnormalities and dysfunction at many levels:
1. Glomerular filtration of albumin
2. Proximal tubular reabsorption of albumin
which can be affected by:
3. Peritubular capillary blood flow/renal perfusion
All these can be transiently and also permanently affeceted in people with DM.
It is high time Nephrologists forget about microalbuminuria and focus on overt and progressive albuminuria (dipstick positive).
It seems to me that the era of obssessive search for, and management of, microalbuminuria is coming to an end. Some of us have argued along these lines for a long time. Otherrs want to expand the search and management of microalbuminuria further beyond people with diabetes to the communtiy as a whoile.
How mislead and misleading they are...!!!