Which components are typically filtered into the nephron's filtrate?

• A. Electrolytes, drugs, glucose, and wastes
• B. Protein and blood cells
• C. Red blood cells
• D. Platelets

Answer: (A)

The glomerular filtration barrier lets small, water-soluble components of plasma pass into the nephron while keeping larger items out. This means the filtrate contains electrolytes (sodium, potassium, chloride, etc.), glucose, and waste products like urea and creatinine, along with any small drug molecules that are not bound to large proteins. Large proteins and formed elements—proteins bound to albumin or larger than a certain size, red blood cells, and platelets—are normally too big or too charged to cross the filtration barrier, so they stay in the blood and do not appear in the filtrate. That’s why the description of what’s filtered best fits electrolytes, glucose, drugs (when small or unbound), and wastes.