Causes of proteinuria ——————————— Prerenal proteinuria ————————– It is also known as Overflow proteinuria or overload proteinuria, it is increased plasma levels of normal or abnormal proteins (e.g., Bence-Jones proteins, globin, and myoglobin) that overwhelms renal capacity to excrete these proteins (small molecular weight proteins present in the blood passing through the filtration barrier). Causes: Myoglobinura Multiple myeloma Malignant lymphoma Acute pancreatitis (amylase in urine) Hypertension Note: High blood pressure is the second leading cause of ESRD. Proteinuria in people with high blood pressure is an indicator of declining kidney function. If the hypertension is not controlled, the person can progress to full renal failure.
Renal proteinuria ————————– Glomerular proteinuria (albuminuria) ——————————————– Develop when normal blood proteins are filtered by the glomeruli in varying amount depending on their molecular mass due to increased glomerular permeability leads to increased intraglomerular capillary pressure which favors transport of small proteins normally present in plasma through the filtration barrier.
Note: Because albumin is relatively small (65,000 daltons), it is the predominant protein lost from the glomerulus. in this case there are marked hypolbuminaemia Causes v Poststreptococcal glomerulonephritis v Nephrotic syndrome: it is the causes of the most severe urinary protein losses.(diagnosed when protein excretion exceeds 3.5 g\day). It may be due to primary glomerular disease (>50% of patients) or occurs secondary to systemic lupus erythematosus (SLE) or diabetes mellitus. It is characterized by:Proteinuria, hypoalbuminemia, hyperlipidemia and edema.
Tubular proteinuria ———————— Develop if the tubules fail to reabsorb proteins that are normally filtered in small amounts by the glomeruli Causes v Pyelonephritis v Nephrotoxic drugs (e.g. aminoglycosides).
Post-renal proteinuria ————————– Post-renal proteinuria occurs when protein enters the urine because of haemorrhage or inflammation within the lower urinary tract or genital tract.
v Inflammation: Inflammation and/or infection anywhere in the urogenital tract, e.g. cystitis, prostatitis, will cause proteinuria from leakage of serum protein along with leukocytes or due to increased vascular permeability.
v Hemorrhage: Hemorrhage frequently results in proteinuria when serum protein accompanies erythrocytes. Hemorrhage can occur anywhere within the urogenital tract (including the kidney itself) but more frequently reflects lower urinary tract (bladder disorders) or reproductive tract disease