Table 1.
Patient characteristics in the development and validation cohorts
| Development cohort | Validation cohort | |||||
|---|---|---|---|---|---|---|
| TPP (n = 39) | HypoK control (n = 502) | P | TPP (n = 11) | non-TPP (n = 36) | P | |
| Sex, male | 39 (100.0%) | 502 (100.0%) | 11 (100.0%) | 36 (100.0%) | ||
| Age, y | 34.7 ± 8.4 | 47.1 ± 10.5 | < .001 | 35.9 ± 7.8 | 52.8 ± 13.1 | < .001 |
| ECG-K + , mEq/L | 2.6 ± 0.6 | 3.0 ± 0.5 | .106 | |||
| Weakness | 39(100.0%) | 50(10.0%) | < .001 | 11(100.0%) | 36(100.0%) | |
| ECG morphology | ||||||
| Heart rate | 95.1 ± 17.5 | 91.5 ± 21.7 | .306 | 100.0 ± 10.1 | 85.3 ± 14.6 | .003 |
| PR interval | 176.0 ± 33.2 | 162.1 ± 37.1 | .025 | 166.1 ± 57.3 | 166.6 ± 40.5 | .674 |
| QRS duration | 101.6 ± 10.8 | 102.3 ± 17.9 | .806 | 96.5 ± 11.1 | 110.2 ± 26.0 | .094 |
| QT interval | 384.3 ± 76.0 | 395.1 ± 55.8 | .257 | 364.6 ± 29.3 | 399.2 ± 47.4 | .023 |
| Correct QT interval | 476.1 ± 81.2 | 480.0 ± 50.4 | .662 | 470.2 ± 43.2 | 471.4 ± 46.0 | 1.000 |
| P waves axes | 65.0 ± 60.6 | 54.8 ± 30.7 | .074 | 51.5 ± 68.6 | 53.1 ± 32.4 | .905 |
| RS waves axes | 57.2 ± 23.3 | 47.5 ± 49.6 | .227 | 47.9 ± 28.7 | 47.4 ± 35.9 | .950 |
| T waves axes | 47.5 ± 79.9 | 42.8 ± 63.5 | .670 | 17.7 ± 50.8 | 49.3 ± 77.3 | .407 |
| Laboratory test | ||||||
| TSH, μIU/mL | 0.0 ± 0.1 | 1.3 ± 1.2 | < .001 | 0.0 ± 0.0 | 1.8 ± 1.4 | .004 |
| Free T4, ng/dL | 2.5 ± 0.6 | 1.0 ± 0.3 | < .001 | 2.7 ± 0.5 | 1.1 ± 0.1 | .003 |
| eGFR, mL/min | 146.2 ± 54.6 | 90.4 ± 59.5 | < .001 | 156.1 ± 43.7 | 91.3 ± 45.6 | < .001 |
| Cr, mg/dL | 0.8 ± 0.6 | 1.7 ± 2.3 | .019 | 0.7 ± 0.2 | 1.6 ± 2.3 | < .001 |
| BUN, mg/dL | 18.0 ± 15.2 | 18.8 ± 15.5 | .748 | 11.7 ± 3.7 | 19.9 ± 16.3 | .117 |
| K+, mEq/L | 2.5 ± 0.6 | 2.8 ± 0.2 | < .001 | 2.5 ± 0.5 | 2.7 ± 0.3 | .027 |
| Na+, mEq/L | 139.2 ± 2.2 | 136.1 ± 5.0 | < .001 | 139.3 ± 1.2 | 137.6 ± 5.0 | .454 |
| Cl–, mEq/L | 106.7 ± 2.3 | 99.4 ± 7.6 | < .001 | 108.0 ± 2.1 | 101.3 ± 7.4 | .005 |
| Ca++, mg/dL | 8.8 ± 0.7 | 8.5 ± 0.8 | .024 | 8.9 ± 0.6 | 8.1 ± 0.9 | .003 |
| Mg++, mg/dL | 1.9 ± 0.3 | 1.9 ± 0.4 | .334 | 2.0 ± 0.2 | 1.8 ± 0.5 | .541 |
Abbreviations: BUN, blood urea nitrogen; Ca++, total calcium; Cl–, chloride; Cr, creatinine; ECG, electrocardiography; ECG-K+, K+ estimated via electrocardiography; eGFR, estimated glomerular filtration rate; Free T4, free thyroxine; HypoK, hypokalemia; K+, potassium; Mg++, magnesium; Na+, sodium; TSH, thyrotropin; TPP, thyrotoxic periodic paralysis.