Is the fractional excretion of uric acid in patients with Syndrome of Inappropriate Antidiuretic Hormone (SIADH) typically above or below 12%?

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From the Research

Fractional Excretion of Uric Acid in SIADH

  • The fractional excretion of uric acid (FE-UA) in patients with Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is typically above 12% 1, 2.
  • A study found that using a cutoff value of 12% for FE-UA resulted in a positive predictive value of 100% for diagnosing SIADH 1.
  • Another study confirmed that FE-UA (>12%) is a better diagnostic marker for distinguishing SIADH patients from non-SIADH patients 2.
  • The high FE-UA in SIADH is thought to be related to the chronicity of hyponatremia, mild volume expansion, and glomerular filtration rate 3.
  • The mechanism of the increase in uric acid excretion in SIADH seems to result from a decrease in the post-secretory reabsorption of uric acid 4.

Comparison with Other Parameters

  • FE-UA was found to be more accurate than other parameters, such as fractional excretion of sodium (FE-Na), in diagnosing SIADH 1, 2.
  • Serum uric acid levels were found to be lower in SIADH patients compared to non-SIADH patients, while urine uric acid levels were higher in SIADH patients 2.
  • The combination of FE-UA and other parameters, such as urine sodium excretion, can lead to a very high diagnostic accuracy in hyponatremic patients with and without diuretic treatment 1.

References

2
Research

Study of Urinary Electrolytes and Fractional Excretion of Uric Acid in Evaluating Hyponatremia.

The Journal of the Association of Physicians of India, 2024

3
Research

Evidence that chronicity of hyponatremia contributes to the high urate clearance observed in the syndrome of inappropriate antidiuretic hormone secretion.

American journal of kidney diseases : the official journal of the National Kidney Foundation, 2000

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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