What Is Fractional Sodium Excretion?
Under normal circumstances, FENa (%) <1. An elongated epithelial tubule connected to the renal capsule wall layer, which has reabsorption and excretion effects. The main physiological function of renal tubules is to absorb water, electrolytes and nutrients (such as glucose, amino acids, etc.) in raw urine, followed by secretion (H +, K + and organic substances), excretion of waste (urea and organic acids, etc.). Concentration and dilution of urine are also important physiological functions of the renal tubules.
Filtered sodium excretion fraction FENa
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- The filtered sodium excretion fraction is also called FENa, which is the determination of the percentage of glomerular filtered sodium and urinary excreted sodium, that is, the percentage of sodium filtered by the glomerulus without being reabsorbed by the renal tubules. Calculation formula: sodium excretion fraction = [(urine sodium × blood creatinine) / (blood sodium × urinary creatinine)] × 100%; sodium excretion fraction is the most sensitive index for distinguishing prerenal acute renal failure and acute tubular necrosis, positive The rate is 98%. Prerenal acute renal failure due to the relatively increased reabsorption of sodium by the renal tubules reduces the urinary sodium excretion and FENa significantly decreases. Acute tubular necrosis, the renal tubular can not absorb Na, so the urine Na excretion increased significantly. Urine sodium excretion can be increased after the application of diuretics, so the sodium excretion fraction cannot be used as a diagnostic basis at this time.
- Name
- Filtered sodium excretion fraction FENa
- category
- Renal function
- Under normal circumstances, FENa (%) <1. An elongated epithelial tubule connected to the renal capsule wall layer, which has reabsorption and excretion effects. The main physiological function of renal tubules is to absorb water, electrolytes and nutrients (such as glucose, amino acids, etc.) in raw urine, followed by secretion (H +, K + and organic substances), excretion of waste (urea and organic acids, etc.). In addition, Concentration and dilution of urine are also important physiological functions of the renal tubules.
- Abnormal results: FENa (%) is a sensitive indicator for distinguishing prerenal azotemia and acute tubular necrosis, FENa (%) <1 for prerenal azotemia, and FENa (%)> 2 for acute tubular necrosis . There is a blank area between 1 and 2. The former reabsorbs sodium and strengthens it, so that FENa (%) even drops to O.1, and the latter often exceeds 3. People to be checked: prerenal azotemia and acute tubular necrosis
- Unsuitable crowd: Generally there is no unsuitable crowd. Contraindications before the test: Maintain a regular schedule and diet to help the test run smoothly. Requirement during the examination: The patient takes urine for examination according to the doctor, and the doctor examines it carefully and observes the results carefully.
- Before the test, patients were allowed to drink 10-20 ml / kg of water. To maintain proper urine output. The doctor took urine for examination, and calculated the result according to the formula after recording the result: sodium excretion fraction = [(urine sodium × blood creatinine) / (blood sodium × urinary creatinine)] × 100%, and the results were compared with normal values to determine the symptoms.
- Pediatric hypochlorine azotemia syndrome, acute tubular necrosis
- Very low sodium excretion, azotemia, renal tubular necrosis, reversible azotemia