Type 2 Renal Tubular Acidosis (RTA) occurs in which part of the nephron?

Type 2 Renal Tubular Acidosis (RTA), also known as proximal renal tubular acidosis, primarily occurs in the proximal convoluted tubule of the nephron. This condition is characterized by a defect in bicarbonate reabsorption in this segment, leading to the inability to adequately acidify urine and resulting in metabolic acidosis. The proximal convoluted tubule is responsible for the reabsorption of a significant amount of bicarbonate, and when there is a failure of this process, it results in bicarbonate wasting and subsequent acidosis.

The proximal convoluted tubule is vital for the absorption of not just bicarbonate but also glucose, amino acids, and other substances. Hence, a malfunction here can lead to various metabolic complications and electrolyte imbalances, often seen in conditions associated with type 2 RTA.

In contrast, the other segments of the nephron do not primarily mediate bicarbonate reabsorption in the way that the proximal convoluted tubule does, which is why they are not associated with type 2 RTA.