Background: Serum osmolality can be measured (Omeas) or calculated (Ocal). Many formulas for Ocal have been already published, but data regarding the most accurate equation in small babies is not available. Thus, we aim to compare Omeas and Ocal obtained by different formulas in newborns and small children.
Methods: The study included 280 serum samples taken from children, from the first day of life to 2 years (mean age 8.2 ± 7.6 months) treated in the University Children's Hospital in Krakow. The serum osmolality was measured by osmometer and calculated by 8 common formulas.
Results: The mean value of Omeas (2 8 5 .8 ± 5 .1 mOsm/kgH2O) was significantly different as compared to the mean values of Ocal (p< 0.01) for all formulas, except Ocal obtained by the formula: 1.86*(N a + K) +1.15*Glu + Urea + 14. According to Bland-Altman analysis, this formula showed the best performance for estimating osmolality. In children under 3 months of life Passing-Bablok regression indicated both systematic and proportional error for results obtained by each formula compared to the measured values.
Conclusions: To calculate osmolarity in children aged between 3 months and 2 years old the following equation: 1 .86*(N a + K) + 1.1 5*G lu+ U rea+ 14 might be used, whereas serum osmolality in children up to 3 month of life should be measured.
Uvod: Osmolalnost seruma se može meriti (Omeas) ili izračunati ( Ocal). Mnoge formule za Ocal su već objavljene, ali podaci o najtačnijoj jednačini kod malih beba nisu dostupni. Stoga želimo da uporedimo O meas i Ocal dobijene različitim formulama kod novorođenčadi i male dece.
Metode: Studija je obuhvatila 280 uzoraka seruma uzetih od dece, od prvog dana života do 2 godine (srednja starost 8,2 ± 7,6 meseci) lečene u Univerzitetskoj dečjoj bolnici u Krakovu. Osmolalnost seruma je izmerena osmometrom i izračunata po 8 uobičajenih formula.
Rezultati: Srednja vrednost Omeas (285,8± 5,1 mOsm/ kgH2O) se značajno razlikovala u poređenju sa srednjim vrednostima Ocal (p< 0,01) za sve formule, osim Ocal dobijene po formuli: 1,86*(N a + K) + 1 ,1 5* Glu + Urea + 14. Prema Bland-Altman analizi, ova formula je pokazala najbolje performanse za procenu osmolalnosti. Kod dece mlađe od 3 meseca života Passing-Bablokova regresija je pokazala i sistematsku i proporcionalnu grešku za rezultate dobjene svakom formulom u poređenju sa izmerenim vrednostima.
Zaključak: Za izračunavanje osmolarnosti kod dece uzrasta između 3 meseca i 2 godine, mogu se koristiti sledeće jednačine: 1,86*(N a + K) + 1,15*Glu + Urea + 14, dok treba meriti osmolalnost seruma kod dece do 3 meseca života.
Keywords: calculation; children; newborns; osmolality; osmolarity.
2023 Joanna Berska, Jolanta Bugajska, Krystyna Sztefko, published by CEON/CEES.