Urinalysis by means of Test Strips
:: Overview :: Parameters :: :: CHRONOLAB
Introduction Determination Clinical significance Risk factors Effect of drugs Finding Sample

Urinalysis - Protein

Introduction

Proteinuria is the occurrence of protein in the urine, usually consequential to a renal parenchyma lesion. A normal kidney prevents the loss of protein by tubular resorption. It has been found that a very small amount of protein is excreted by primary urine, and undergoes tubular reabsorption, so that final urine contains very low amounts of protein that cannot be demonstrated by routine examinations (test strip).
In normal individuals, urinary excretion of protein amounts to up to 150 mg protein daily. Due to limited permeability of the renal glomerular membrane, these proteins are of a low molecular mass (mostly albumins).

Physiologic proteinuria is always transient and occurs consequentially to physical exertion, sport activities, following intake of protein-rich food, after exposure to low temperature, and in late pregnancy.

According to the site of onset, pathologic proteinurias are classified as follows:
1. prerenal proteinurias
2. renal proteinurias
a) glomerular proteinuria
b) tubular proteinuria
3. postrenal proteinurias

1. Prerenal proteinurias develop as a consequence of a process occurring 'before' the kidney. Proteins of a low molecular mass that are not reabsorbed in the tubules, e.g. Bence-Jones protein, pass to the urine. This type of proteinuria also occurs in some heart diseases with circulation disorders, some liver diseases, and with elevated body temperature.
2. Renal proteinurias occur due to increased tubular permeability or lesion. These proteinurias are usually permanent.
3. Postrenal proteinurias develop consequentially to inflammatory processes of the lower genitourinary tract (urinary bladder, urinary duct, prostate or vagina).

Orthostatic proteinuria is a sequel of elevated renal intravenous pressure. It occurs in children and young individuals, only while walking or standing, and disappearing on lying down and at rest. The so-called orthostatic test is performed to demonstrate orthostatic proteinuria. Protein concentration in 24-hour urine usually is below 1000 mg/L, whereas in individual specimens it may range between 500 and 1000 mg/L. Orthostatic proteinuria is not considered a disease, however, these individuals should be followed up because studies have shown that 35% of cases of orthostatic proteinuria progress to permanent proteinuria.
    ::   Terms of use   ::   Note     ::  Contact    ::      Print  ::    

Legal Information - The information provided on this web site is for educational purpose only and in no way should it be considered as offering medical advice. The information provided here should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. Additionally, all laboratory services offered on this web site are for screening purpose only. If you have, or suspect you may have, a health problem, you should consult your physician. We assume no responsibility for how this material is used.