Kidney Functions and Nephron Structure

Kidney Functions

• Fluid & Electrolyte Balance: Kidneys regulate the amount of water and electrolytes in the body through reabsorption and secretion processes.
• Acid-Base Balance: Kidneys maintain the correct pH balance in the blood by excreting excess acids or bases.
• Red Blood Cell Production (Erythropoiesis): Kidneys produce erythropoietin, a hormone that stimulates red blood cell production in the bone marrow.
• Blood Pressure Regulation: Kidneys secrete renin, an enzyme that plays a crucial role in regulating blood pressure.

Nephron: The Functional Unit of the Kidney

• Filtration: Blood enters the nephron and is filtered through the glomerulus.
• Reabsorption: Water and small molecules such as glucose, amino acids, sodium, chloride, calcium, and bicarbonate are reabsorbed back into the bloodstream.
• Secretion: Substances like potassium, phosphate, hydrogen, ammonium, and some acidic drugs are secreted into the filtrate.
• Loop of Henle: Solely responsible for reabsorption processes within the nephron.

Renal Failure (Chronic Kidney Disease - CKD)

• Reduced Kidney Function: Characterized by a decrease in the kidney's ability to function properly.
• Common Causes: Uncontrolled hypertension and diabetes mellitus are leading causes of CKD.
• Drug Accumulation: Drugs can accumulate to high levels in the body due to impaired kidney function.
• Dosage Adjustments: Medication dosages may need adjustment to compensate for reduced kidney function.

Renal Failure

• Renal failure is a decrease in the kidneys' ability to function.
• Untreated hypertension and diabetes mellitus are leading causes.
• Drug accumulation to high levels is a consequence of renal failure.
• Medication dosages may need to be adjusted in patients with renal failure.
• Administering an average dose to a person with renal failure can be fatal.

Diagnosis of Renal Failure

• Urinalysis is a diagnostic tool for renal failure.
• Serum creatinine levels rise when the kidneys don't process or eliminate creatinine effectively, indicating impaired kidney function.
• Blood urea nitrogen (BUN) levels are influenced by factors like hydration status.
• Dehydration can lead to concentrated blood, resulting in elevated BUN levels.
• Overhydration can lead to diluted blood, resulting in lower BUN levels.
• If a patient's creatinine is normal but BUN is high, it may suggest dehydration and kidney failure.
• Diagnostic imaging can assist in diagnosing renal failure.
• Renal biopsy offers a definitive diagnosis of renal failure.