Total protein > upper reference value of 83 g/L, w

Supplementary Table 1. Sodium results of patient cohort (n=4006)

Total protein (g/L)

Total

<30 30-40 40-50 50-60 60-70 >70*

Number of samples 45 290 1203 1475 732 261 4006

|Na⁺indirect – Na⁺direct| ≤ 4 mmol/L 2

(4%)

43 (15%)

482 (40%)

1095 (74%)

699 (95%)

243 (93%)

2564 (64%)

|Na⁺indirect – Na⁺direct | > 4 mmol/L 43 (96%)

247 (85%)

721 (60%)

380 (26%)

33 (5%)

18 (7%)

1442 (36%)

 hypo → hyponatremia 3 13 28 20 2 3 69

 normo → pseudohyponatremia 0 0 0 0 0 2 2

 hyper → pseudohyponatremia 0 0 0 0 0 1 1

 hypo → pseudonormonatremia 20 111 243 125 10 4 513

499/3013 (17%)

 normo → normonatremia 4 78 304 167 11 5 569

 hyper → pseudonormonatremia 0 0 0 2 2 0 4

 normo → pseudohypernatremia 14 37 123 50 4 3 231

224/3013 (7%)

 hyper → hypernatremia 2 8 23 16 4 0 53

* 36/261: Total protein > upper reference value of 83 g/L, with 7/36 |Na⁺Indirect – Na⁺Direct | > 4 mmol/L Distribution of the sodium results of the total patient cohort (n=4006) categorized by total protein concentration. A further split-up is made between absolute differences (Na⁺_indirect - Na⁺_direct) ≤ or > 4 mmol/L. In the latter group, further information is given about the clinical impact (i.e. hyper  pseudohyponatremia = Na⁺_direct result >145 mmol/L which corresponds with an Na⁺indirect result (falsely) below 135 mmol/L).