Severe Underestimation of Serum Na following IVIG Treatment. 

 -  2018 
<br/><br/> Current chemistry analyzers measure ion concentration using ion- selective electrodes; however, may differ in the specific technology at the bedside versus the central laboratory. Instruments utilized for point-of-care testing (POCT) at the bedside use direct ion-selective electrodes, whereas central-laboratory analyzers use indirect ion-selective electrodes. Under most circumstances, these instruments will deliver the same result; however, various substances can cause interferences in one or the other. An 18-year-old Hispanic woman with a history of immune thrombocytopenic purpura (ITP) presented at Children's National Medical Center (CNMC) with a severe headache and required intravenous immunoglobulin (IVIG) therapy. Because a discrepancy developed between her point-of-care and central-laboratory sodium values, another instrument was used to retest the central-laboratory plasma specimens. The results were more in agreement with those from the point-of-care instrument and revealed a unique interference in sodium measurement related to IVIG use. 
<br/><br/><br/>English 
<br/><br/><label>ISSN: </label>0007-5027 
<br/><br/><label>Standard No.: </label>10.1093/labmed/lmy025 [doi] 5036164 [pii] 
<br/><br/><label>Subjects--Topical Terms: </label><br/>*Immunoglobulins, Intravenous/tu [Therapeutic Use]<br/>*Purpura, Thrombocytopenic, Idiopathic/bl [Blood]<br/>*Purpura, Thrombocytopenic, Idiopathic/dt [Drug Therapy]<br/>*Sodium/bl [Blood]<br/>Adolescent<br/>Diagnostic Errors<br/>Female<br/>Humans<br/>Purpura, Thrombocytopenic, Idiopathic/di [Diagnosis]<br/>Purpura, Thrombocytopenic, Idiopathic/pp [Physiopathology]<br/>Reproducibility of Results
<br/><br/><label>Subjects--Geographic Terms: </label><br/>MedStar Washington Hospital Center
<br/><br/><label>Index Terms--Occupation: </label><br/>Pathology
<br/><br/><label>Index Terms--Function: </label><br/>Journal Article