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Diagnostic value of urine sodium concentration in hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion versus hypovolemia.
Hawaii Med J. 2010 Nov; 69(11):264-7.HM

Abstract

BACKGROUND

We are often left with the differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) versus hypovolemic hyponatremia. It is difficult to tell who will respond to isotonic saline infusion and who will not, if the urine sodium value is not completely suppressed (>10 mEq/L).

AIM

To examine the diagnostic accuracy of the urine sodium value.

DESIGN

A retrospective observation.

METHODS

The diagnostic accuracy of the urine sodium value was compared to that of a complete work-up and hospital course, including a response to saline infusion in patients with a final diagnosis of SIADH or hypovolemic hyponatremia. We also examined the diagnostic value of urine sodium-to-BUN ratio which should improve separation between SIADH and hypovolemia since the urine sodium and BUN move in opposite directions in these two conditions.

RESULTS

The urine sodium value of 50 mEq/L was the most accurate in separating SIADH from hypovolemic hyponatremia: sensitivity 0.89, specificity 0.69, and accuracy 0.82. The diagnostic utility for SIADH versus hypovolemia, as quantified by the areas under the ROC curves, was not statistically different between urine sodium alone (0.89, 95% CI 0.77-0.96) and urine sodium-to-BUN ratio (0.93, 95% CI 0.83-0.98); p-value 0.33.

CONCLUSIONS

When the underlying cause is inconclusive between SIADH and hypovolemia, and when only basic laboratory results are available at the time of initial evaluation, the urine sodium alone will be adequate to guide initial fluid management. In contrast to traditional teaching, elevated urine sodium levels up to 50 mEq/L demonstrated clinically meaningful responses to isotonic saline infusion.

Authors+Show Affiliations

Department of Medicine, Indiana University, Indianapolis, IN 46202, USA. thato@iupui.eduNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

21218377

Citation

Hato, Takashi, and Roland Ng. "Diagnostic Value of Urine Sodium Concentration in Hyponatremia Due to Syndrome of Inappropriate Antidiuretic Hormone Secretion Versus Hypovolemia." Hawaii Medical Journal, vol. 69, no. 11, 2010, pp. 264-7.
Hato T, Ng R. Diagnostic value of urine sodium concentration in hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion versus hypovolemia. Hawaii Med J. 2010;69(11):264-7.
Hato, T., & Ng, R. (2010). Diagnostic value of urine sodium concentration in hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion versus hypovolemia. Hawaii Medical Journal, 69(11), 264-7.
Hato T, Ng R. Diagnostic Value of Urine Sodium Concentration in Hyponatremia Due to Syndrome of Inappropriate Antidiuretic Hormone Secretion Versus Hypovolemia. Hawaii Med J. 2010;69(11):264-7. PubMed PMID: 21218377.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Diagnostic value of urine sodium concentration in hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion versus hypovolemia. AU - Hato,Takashi, AU - Ng,Roland, PY - 2011/1/11/entrez PY - 2011/1/11/pubmed PY - 2011/3/25/medline SP - 264 EP - 7 JF - Hawaii medical journal JO - Hawaii Med J VL - 69 IS - 11 N2 - BACKGROUND: We are often left with the differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) versus hypovolemic hyponatremia. It is difficult to tell who will respond to isotonic saline infusion and who will not, if the urine sodium value is not completely suppressed (>10 mEq/L). AIM: To examine the diagnostic accuracy of the urine sodium value. DESIGN: A retrospective observation. METHODS: The diagnostic accuracy of the urine sodium value was compared to that of a complete work-up and hospital course, including a response to saline infusion in patients with a final diagnosis of SIADH or hypovolemic hyponatremia. We also examined the diagnostic value of urine sodium-to-BUN ratio which should improve separation between SIADH and hypovolemia since the urine sodium and BUN move in opposite directions in these two conditions. RESULTS: The urine sodium value of 50 mEq/L was the most accurate in separating SIADH from hypovolemic hyponatremia: sensitivity 0.89, specificity 0.69, and accuracy 0.82. The diagnostic utility for SIADH versus hypovolemia, as quantified by the areas under the ROC curves, was not statistically different between urine sodium alone (0.89, 95% CI 0.77-0.96) and urine sodium-to-BUN ratio (0.93, 95% CI 0.83-0.98); p-value 0.33. CONCLUSIONS: When the underlying cause is inconclusive between SIADH and hypovolemia, and when only basic laboratory results are available at the time of initial evaluation, the urine sodium alone will be adequate to guide initial fluid management. In contrast to traditional teaching, elevated urine sodium levels up to 50 mEq/L demonstrated clinically meaningful responses to isotonic saline infusion. SN - 0017-8594 UR - https://www.unboundmedicine.com/medline/citation/21218377/Diagnostic_value_of_urine_sodium_concentration_in_hyponatremia_due_to_syndrome_of_inappropriate_antidiuretic_hormone_secretion_versus_hypovolemia_ L2 - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21218377/ DB - PRIME DP - Unbound Medicine ER -