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1. Proximal Tubule Functions
- Reabsorption of:
- Sodium (Na+), Potassium (K+), Chloride (Cl-), and Bicarbonate (HCO3−)
- Glucose, amino acids, phosphate, and uric acid
- Secretion of organic acids and bases
- Production of ammonia (NH3)
2. Loop of Henle Functions
- Reabsorption of water in the descending limb
- Reabsorption of Na+, Cl-, and K+ in the ascending limb
- Establishment of the medullary concentration gradient
3. Distal Tubule and Collecting Duct Functions
- Reabsorption of Na+ and secretion of K+ and H+
- Fine-tuning of water reabsorption under the influence of antidiuretic hormone (ADH)
- Acid-base regulation
Tests to Evaluate Proximal Tubular Disorders
- Bicarbonate Reabsorption:
- Venous Blood Gas (VBG): Low serum bicarbonate (metabolic acidosis).
- Urinary pH: Normal or mildly reduced (despite acidosis).
- Glucose Reabsorption:
- Urine Glucose Testing: Positive for glucose despite normal blood glucose levels (renal glycosuria).
- Phosphate Reabsorption:
- Serum Phosphate: Hypophosphatemia.
- Urine Phosphate: Increased urinary excretion of phosphate.
- Amino Acid Reabsorption:
- Aminoaciduria: Detected via urine chromatography.
- Urinary Concentration Capacity:
- Fractional Excretion of Solutes: Elevated values for solutes like sodium, uric acid, and potassium.
Treatment of Proximal Renal Tubular Acidosis (pRTA) in Children
- Alkali Therapy:
- Sodium bicarbonate or potassium citrate to correct acidosis.
- Target serum bicarbonate: 20-22 mEq/L.
- Potassium Supplementation:
- Correct hypokalemia with oral potassium chloride or potassium citrate.
- Phosphate Supplementation (if necessary):
- To treat hypophosphatemia if present.
- Vitamin D and Calcium:
- If rickets or osteomalacia is present, provide calcitriol and calcium.
- Dietary Management:
- Adequate hydration and a diet rich in fruits and vegetables to maintain acid-base balance.
- “Proximal renal tubular acidosis treatment in children”
- “Tests to diagnose proximal tubule dysfunction”
- “Renal tubular acidosis pediatric management guidelines”
- “Role of bicarbonate in treating pRTA in children”
- “Symptoms of proximal tubule renal disorder in kids”
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