Renal (Kidney) Function and Hormonal Regulation (copy)

Microalbumin Tests: Microalbumin tests measure small amounts of albumin in the urine. They serve as a sensitive early indicator of glomerular damage, especially in individuals with diabetes.

ADH (Antidiuretic Hormone) Cycle:

  • When Hydration is increased: ADH decreases, leading to increased urine output.

  • When Hydration is decreased: ADH increases, which results in decreased urine output.

Physiological Effect of ADH: ADH promotes water reabsorption in the kidneys, particularly in the Distal Convoluted Tubule (DCT), and causes vasoconstriction, aiding in blood pressure regulation.

Major Chemical Components Secreted/Absorbed by the Kidneys:

  • Electrolytes (sodium, potassium, calcium)

  • Various waste products (urea, creatinine)

  • Water

  • Bicarbonate ions (for pH regulation)

Regulation of Body pH: The kidneys regulate body pH through the absorption and secretion of bicarbonate and hydrogen ions, maintaining acid-base balance.

Purpose of the Glomerulus: The glomerulus filters blood to create filtrate, selectively allowing water, ions, and small molecules to pass while retaining larger molecules like proteins and cells.

Lab Tests Indicating Glomerular Functioning:

  • Glomerular Filtration Rate (GFR) measures how well the kidneys filter waste from the blood.

  • Creatinine clearance measures the efficiency in filtering creatinine, a waste product of muscle metabolism.

Purpose of the Tubules: The renal tubules reabsorb essential substances (water, electrolytes) and secrete waste products, fine-tuning urine composition.

Lab Tests for RAAS Functioning:

  • Plasma Renin Activity (PRA) assesses the activity of renin, a key component in the RAAS system.

  • Aldosterone levels can be measured to determine the function of the RAAS.

Purpose/Functions and Physiological Effects of:

  • Renin: An enzyme that converts angiotensinogen to angiotensin I, regulating blood pressure and fluid balance.

  • Angiotensinogen II: A potent vasoconstrictor that increases blood pressure and stimulates aldosterone release.

  • Aldosterone: Promotes sodium reabsorption in the kidneys, leading to water retention and increased blood volume.

Impact on Blood Pressure:

  • Renin increases blood pressure through the RAAS cascade, leading to fluid retention and vasoconstriction.

  • Angiotensin II and aldosterone both elevate blood pressure by promoting vasoconstriction and sodium retention, respectively.

What Creatinine Is: A waste product generated from muscle metabolism, filtered out of the blood by the kidneys. What Creatinine Indicates: The level of creatinine in blood and urine is an indicator of kidney function and health. Normal Glomerular Filtration Rate: Healthy GFR ranges from 90 to 120 mL/min, indicating efficient kidney function. Normal Serum BUN to Creatinine Ratio: Typically between 10:1 and 20:1; a ratio of <10:1 may indicate kidney dysfunction.

Water in the Kidneys:

  • Reabsorption occurs primarily in the kidney tubules, especially the proximal tubule and loop of Henle.

  • Secretion is minimal.

Assessing Renal Concentrating Ability: Osmolality tests measure the kidneys' ability to concentrate urine; higher osmolality indicates a greater concentrating ability of the kidneys.