TABLE 1.
Clinical characteristics of COVID-19 patients with or without hyponatremia at presentation.
| Hyponatremia (n = 14,545) | Normonatremia (n = 36,182) | P-value | |
| Age | 74.3 ± 16.1 | 62.4 ± 22.0 | <0.001a |
| Age older than 65, No. (%) | 10,887 (74.9%) | 17,679 (48.9%) | <0.001b |
| Male, No. (%) | 8,237 (56.6%) | 18,103 (50.0%) | <0.001b |
| Comorbidities | |||
| Diabetes mellitus | 4,968 (34.2%) | 7,184 (19.9%) | <0.001b |
| Hypertension | 7,910 (54.4%) | 13,618 (37.6%) | <0.001b |
| Ischemic heart disease | 2,245 (15.4%) | 3,724 (10.3%) | <0.001b |
| Cerebrovascular accident | 1,826 (12.6%) | 2,847 (7.9%) | <0.001b |
| Cardiac arrhythmia | 2,241 (15.4%) | 3,858 (10.7%) | <0.001b |
| Congestive heart failure | 1,472 (10.1%) | 2,676 (7.4%) | <0.001b |
| Chronic obstructive airway disease | 954 (6.6%) | 1,604 (4.4%) | <0.001b |
| Asthma | 279 (1.9%) | 593 (1.6%) | =0.03b |
| Pneumoconiosis | 201 (1.4%) | 242 (0.7%) | <0.001b |
| Dementia | 1,732 (11.9%) | 3,380 (9.3%) | <0.001b |
| Chronic liver disease | 1,033 (7.1%) | 2,026 (5.6%) | <0.001b |
| Active malignancy | 3,003 (20.6%) | 5,517 (15.2%) | <0.001b |
| Chronic kidney disease (eGFR < 90 ml/min) | 12,004 (82.5%) | 24,145 (66.7%) | <0.001b |
| eGFR 60–90 ml/min (Stage 2) | 7,304 (50.2%) | 16,915 (46.7%) | |
| eGFR 30–59 ml/min (Stage 3) | 2,869 (19.7%) | 4,860 (13.4%) | |
| eGFR 15–29 ml/min (Stage 4) | 915 (6.3%) | 1,435 (4.0%) | |
| eGFR <15 ml/min (Stage 5) | 916 (6.3%) | 934 (2.6%) | |
| Laboratory parameters | |||
| Hemoglobin (g/dL) | 11.9 ± 2.2 | 12.8 ± 2.2 | <0.001a |
| White cell count (109/L) | 8.7 ± 7.0 | 7.0 ± 4.0 | <0.001a |
| Neutrophil (109/L) | 6.5 ± 4.7 | 4.9 ± 3.4 | <0.001a |
| Lymphocyte (109/L) | 1.0 ± 1.9 | 1.3 ± 1.0 | <0.001a |
| Neutrophil to lymphocyte ratio | 9.1 ± 10.2 | 5.6 ± 7.2 | <0.001a |
| Platelet (109/L) | 221 ± 102 | 223 ± 88 | 0.05a |
| Sodium (mmol/L) | 129.9 ± 5.6 | 138.6 ± 2.3 | <0.001a |
| Potassium (mmol/L) | 4.0 ± 0.7 | 3.9 ± 0.5 | <0.001a |
| Urea (mmol/L) | 8.8 ± 8.0 | 6.7 ± 6.1 | <0.001a |
| Creatinine (umol/L) | 144 ± 205 | 103 ± 124 | <0.001a |
| eGFR (by CKD-EPI equation) | 65.2 ± 31.1 | 79.7 ± 31.1 | <0.001a |
| Albumin (g/L) | 32.9 ± 6.4 | 36.8 ± 6.4 | <0.001a |
| C-reactive protein (mg/L) | 6.7 ± 7.1 | 3.7 ± 5.9 | <0.001a |
| Calcium (mmol/L) | 2.16 ± 0.17 | 2.23 ± 0.15 | <0.001a |
| Phosphate (mmol/L) | 1.11 ± 0.49 | 1.09 ± 0.37 | <0.001a |
| Osmolality (mOsm/kg) | 269 ± 22 | 302 ± 33 | <0.001a |
| Thyroid stimulating hormone (mIU/L) | 1.6 ± 3.6 | 1.7 ± 3.8 | 0.5a |
| Creatine kinase (U/L) | 410 ± 1491 | 250 ± 1599 | <0.001a |
| D-dimer (ng/ml) | 1284 ± 1871 | 862 ± 1567 | <0.001a |
| Urine sodium (mmol/L) | 49.0 ± 34.5 | 50.3 ± 40.7 | 0.6a |
| Urine osmolality | 407 ± 165 | 438 ± 196 | 0.01a |
Data are presented as mean ± standard deviation unless specified and compared by Student’s t-testa and chi-square testb. COVID-19, coronavirus disease-2019; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; RT-PCR, reverse transcription polymerase chain reaction; Ct value, cycle threshold value; eGFR, estimated glomerular filtration rate; CKD-EPI, chronic kidney disease epidemiology collaboration.