Expert: John Locke - 11/3/2009

Question
How is the urine of someone with damage to their cells in the glomerulus and glomerular capsule likely to be different than that of someone with an intact filter?

Answer
Thanks for using AllExperts. The function of the glomerular cells is to provide a first-pass filter for the blood plasma as it passes through the kidneys. Glomerular cells provide a barrier that allows fluid and small molecules to pass into the renal tubule system; proteins and blood cells are blocked and remain within the blood. Much of the water and ions that pass into the renal tubule system are then filtered back into the bloodstream; certain waste products are actively secreted from the bloodstream into the urine at the same time. The net result is generally a more concentrated urine, relative to the blood plasma, with a high proportion of nitrogenous wastes.

Damage to the glomerular cells compromises this filter and allows larger proteins into the renal tubule system, and from there into the urine. Albumin is such a protein, and its presence in the urine is suspicious for some kind of glomerular damage. The urine will have a lower concentration of all solutes because more water will be lost from the renal tubule system than normal. Larger absolute amounts of glucose and sodium will be found--normally these would be reabsorbed, but too much has been lost into the renal tubules to be salvaged in this case. Red and white blood cells would be present; these are normally not present in urine.

If you have any further questions, I would be happy to answer them.