Graded interference with the direct potentiometric measurement of sodium by hemoglobin
| Autor: | Robert H. Barth, Andrea Roche-Recinos, Philip Goldwasser |
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| Rok vydání: | 2017 |
| Předmět: |
Male
Erythrocytes Bicarbonate Sodium Clinical Biochemistry Potentiometric titration 030232 urology & nephrology Analytical chemistry chemistry.chemical_element General Medicine 030204 cardiovascular system & hematology Continuous variable Hemoglobins 03 medical and health sciences chemistry.chemical_compound Categorical analysis 0302 clinical medicine chemistry Linear regression Potentiometry Humans Female Hemoglobin Total protein |
| Zdroj: | Clinical Biochemistry. 50:440-443 |
| ISSN: | 0009-9120 |
| DOI: | 10.1016/j.clinbiochem.2016.12.009 |
| Popis: | Objectives Sodium concentration is measured by either indirect (I Na ) or direct potentiometry (D Na ), on chemistry and gas panels, respectively. A spurious difference between these methods (ΔNa = I Na − D Na ) can be confusing to the clinician. For example, variation in serum total protein (TP) is well known to selectively interfere with I Na . Red cells have been suggested to interfere with D Na , but both positive and negative interference have been reported. In this study, the effect of gas panel hemoglobin (Hb) on ΔNa was examined. Methods ΔNa was calculated in 772 pairs of closely-timed chemistry and gas panels (median: 4 min. apart), retrospectively collected from our critical care units, with 1 pair per patient. Hb was treated as a categorical or continuous variable and tested for linear and non-linear effects, with adjustment for 3 known influences on ΔNa—TP, bicarbonate (tCO 2 ), and the chemistry-gas panel glucose difference (ΔGlu). Results Hb ranged from 3.5 to 22.0 g/dL [35–220 g/L]. In categorical analysis, ΔNa increased with Hb, and the effect was essentially linear. By simple regression, ΔNa rose 0.06 ± 0.03[SE] mmol/L per 1 g/dL [10 g/L] increase in Hb (p − 3 ) with TP, tCO 2 , and ΔGlu. Using multiple regression to adjust for the confounders, ΔNa rose 0.15 ± 0.03 mmol/L per 1 g/dL [10 g/L] rise in Hb ( p − 6 ). Conclusions Increasing Hb spuriously decreases D Na and increases ΔNa. A linear correction for this artifact can reduce the discordance between I Na and D Na , promoting their interchangeable use. |
| Databáze: | OpenAIRE |
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