What can lead to proteinuria?

Proteinuria, which is the presence of abnormal amounts of protein in the urine, can be a significant indicator of kidney function and overall health. Nephritis, or inflammation of the kidneys, can disrupt the normal filtration process that takes place in the glomeruli, leading to an increased permeability of the filtration barrier. This increased permeability allows proteins, such as albumin, to leak from the bloodstream into the urine, resulting in proteinuria.

When the kidneys are inflamed or damaged, their ability to retain proteins diminishes, which directly results in higher levels of protein in urine. Nephritis may occur due to various reasons such as infections, autoimmune diseases, or exposure to toxins, making it a critical condition that can dramatically affect kidney function.

The other choices do not directly contribute to proteinuria in the same way. While high fluid intake could dilute the urine, it would not typically cause a significant increase in protein levels. Joint inflammation, while it can be associated with systemic diseases affecting the kidneys, does not inherently lead to proteinuria. Muscle development may lead to increased levels of certain proteins (like creatine) in the urine but does not typically result in proteinuria as seen with kidney issues. Hence, nephritis is identified as a primary cause