Concentration test

Concentration test is a method to check whether glomerular acidification is normal. The principle is that under normal circumstances, the renal tubules have good urine concentration and dilution functions. Changes in plasma osmotic pressure (Posm) can cause an increase or decrease in the secretion of antidiuretic hormone (ADH). ADH regulates the reabsorption of water by distal renal tubules, and urine volume, specific gravity and osmotic pressure (Uosm) also occur. change. When water intake decreased, Posm increased, ADH secretion increased, distal renal tubular reabsorption increased water, and urine output decreased, while Uosm and urine specific gravity increased, and the opposite change occurred when water intake increased. This is the concentration-dilution function of renal tubules. When the tubule-interstitial tissue is damaged, it does not respond to ADH or decreases its reactivity, and weakens the concentration-dilution effect on urine, no matter how much the Posm changes, while the urine volume and urine specific gravity are relatively constant with Uosm.