Chapters 22 & 23: Renal and Urological Disorders

Study Notes

Filtration: Eliminates metabolic wastes such as urea, uric acid, ammonia, and creatinine, along with drugs and foreign substances from the bloodstream.
Reabsorption: Balances water and electrolytes and maintains acid-base levels by excreting hydrogen ions and reabsorbing bicarbonate.
Secretion: Produces erythropoietin for red blood cell production, activates vitamin D for calcium absorption, and secretes renin to regulate blood pressure via the RAAS.

Antidiuretic Hormone (ADH):
- Produced by posterior pituitary.
- Responsible for water reabsorption; high levels result in concentrated urine, while low levels lead to dilute urine.
Aldosterone:
- Secreted by the adrenal cortex.
- Regulates sodium and water reabsorption to control fluid balance.

Glomerular Filtration Rate (GFR):
- Key measure of kidney function, indicating renal blood filtration per time unit.
- GFR over 90 mL/min suggests good kidney function; below 60 mL/min indicates diminished function.
- Blood pressure is closely linked to kidney health.

Activated by decreased kidney perfusion or low sodium levels.
Renin initiates the conversion of angiotensin to its active forms:
- Angiotensin causes vasoconstriction, raising blood pressure.
- Aldosterone promotes sodium and water reabsorption, thereby increasing blood volume and pressure.

GFR: Best indicator of kidney filtration effectiveness.
Urine Creatinine Clearance (CrCl): Measures kidney's ability to clear creatinine.
Serum Creatinine: Elevated levels indicate impaired kidney function.
Blood Urea Nitrogen (BUN): Assesses nitrogen waste in the blood.

Results in metabolic waste accumulation, leading to uremia, anemia, and cognitive disturbances.
Decreased urine production leads to oliguria or anuria.
Imbalances include:
- Hyperkalemia: Excess potassium linked to cardiac risks.
- Metabolic acidosis: Inefficient H+ ion excretion.
- Reduced erythropoietin leads to anemia; decreased vitamin D activation causes hypocalcemia.

Pyelonephritis:
- Kidney infection primarily caused by E. coli.
- Symptoms include flank pain, fever, chills, nausea, vomiting, and hematuria.
Acute Glomerulonephritis (AG):
- Often follows streptococcal infections, results in edema, oliguria, dark hematuria, and proteinuria.
Nephrotic Syndrome:
- Glomerular damage often due to diabetes, causing proteinuria, edema, and hypoalbuminemia, similar to AG.
Polycystic Kidney Disease (PKD):
- Genetic condition leading to cyst formation in kidneys, resulting in impaired function and hypertension.
- Symptoms include pain from cyst pressure, kidney stones, and hematuria.