University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

418

Pages:

2
Author:

Mariam A.

Proteinuria    Glomerular capillary wall limits filtration of anionic macromolecules (albumin) by sizeselective and charge selective properties. Studies in diabetic subjects with microalbuminuria demonstrate: o An increase in the number of large pores (limiting size-selectivity) o A decreased staining for heparin sulphate (a major component of the charge barrier) These defects cause an increased glomerular permeability is consequence of a variety of pathological processes damaging components of glomerular capillary – endothelium, GBM or epithelium (podocytes). Defects become more prominent with progression to overt proteinuria. Thus albumin, which is not normally filterable through the GBM, ends up in the urine and thus becomes a marker of glomerular disease There are 3 types of proteinuria: o Glomerular proteinuria: a result of glomerular hyperfiltration of high molecular weight macromolecules, such as albumin (for example, in diabetic nephropathy). It is the only proteinuria that is recognised by dipstick o Tubular proteinuria: an increased excretion of low molecular weight molecules, which are normally filtered through the glomerulus and completely reabsorbed in proximal tubules, but due to tubulointerstitial disease there are reduced reabsorption and increased excretion o Overflow proteinuria: a result of hyperproduction of low molecular weight molecules, such as immunoglobulin light chains. Hyperproduction overcomes the reabsorptive capacity of the proximal tubules, and reduces reabsorption due to its toxicity Urinary Dipstick     The standard urinary dipstick is based on the colorimetric reaction between albumin and tetrabromophenol blue, resulting in different shades of green respective of the albumin level. It is a relatively insensitive marker for protein excretion, as it does not become positive until protein excretion exceeds 300-500 mg/day. It cannot detect non-albumin proteins In T1DM, the presence of microalbuminuria is usually the first clinical manifestation of diabetic nephropathy In T2DM, it is usually related to diabetic nephropathy, but could also be related to cardiovascular disease In a non-diabetic patient, it represents an increased risk for cardiovascular disease and an increased early cardiovascular mortality Diabetic nephropathy and kidney function  In diabetic nephropathy, kidney function reduces and the amount of protein in the urine increases: 1) Microalbuminuria (kidney test normal),but have glomerular hyperfiltration + eGFR rise 2) Over 10-15 years the proteinuria increases and nephrotic syndrome may develop 3) With the development of proteinuria, the renal function deteriorates. 5-10 years later the kidneys are almost completely unable to remove “waste products” from the blood 4) End-stage renal disease (ESRD) results, unless treated “waste products” can build up to fatal levels