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  Urine anion gap

Urine Na  
Urine K  
Urine Cl  

Important: Inputs must be complete to perform calculation.

Urine AG  
Decimal Precision  

  Data action

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  • The urine anion gap is calculated from the difference between the major measured urinary cations (Na and K) and urinary anions (Cl).
  • The normal value on a regular diet is -20 to -50 meq/L due to the appropriate presence of ammonium, which is an unmeasured cation.

Equations used
UrineAG = (UrineNa + UrineK) - UrineCl


  1. LaGow B, et al. PDR lab advisor. 1st edition, Montvale, Thompson PDR, 2001. NLMN ID: 101305336 NCBI Logo
  2. Pagana, KD. Mosby's manual of diagnostic and laboratory tests. 6th edition, St. Louis, Elsevier, 2018. NLMN ID: 101720784 NCBI Logo
  3. Kee JL, Paulanka BJ, Polek C. Handbook of fluid, electrolyte, and acid-base imbalances. 3rd edition, Albany, Delmar, 2000. NLMN ID: 100883303 NCBI Logo
  4. Halperin ML, Kamel KS, Goldstein MB. Fluid, electrolyte, and acid-base physiology : a problem-based approach. 4th edition, Philadelphia, Saunders/Elsevier, 2010. NLMN ID: 101472994 NCBI Logo

Associated Logical Observation Identifiers Names and Codes [LOINC]
Parameter LOINC's and Suggested Units
Urine Na 2955-3 : mEq/L      35678-2 : mEq/L      2955-3 : mmol/L      35678-2 : mmol/L      
Urine K 2828-2 : mEq/L      
Urine Cl 2078-4 : mEq/L      35676-6 : mEq/L      
Urine AG 47561-6 : mEq/L      

This material contains content from LOINC (http://loinc.org). LOINC is copyright © 1995-2023, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license. LOINC® is a registered United States trademark of Regenstrief Institute, Inc.

Associated ICD10-CM Codes
   E87.8Other disorders of electrolyte and fluid balance, not elsewhere classified

Associated ICD9-CM Codes
   276.9Electrolyt/fluid dis nec


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