Table 1.
Baseline characteristics of study participants at DHS-1 in the entire cohort according to serum magnesium quintiles (mg/dL)
| Characteristics | Entire cohort n = 2056 | Q1 ≤1.9 n=460 | Q2 2.0 n=440 | Q3 2.1 n=483 | Q4 2.2 n=403 | Q5 ≥2.3 n=270 | P trend |
|---|---|---|---|---|---|---|---|
| Demographics | |||||||
| Age, years | 44.2±10.0 | 42.9±10.3 | 43.4±9.7 | 43.9±9.6 | 45.1±10.2 | 46.5±9.8 | <0.001 |
| Gender (male), % | 41.9 | 26.5 | 41.6 | 42.2 | 51.6 | 53.7 | <0.001 |
| Race, % | <0.001* | ||||||
| Hispanic | 14.0 | 11.3 | 13.4 | 15.1 | 15.1 | 15.9 | |
| Non-Hispanic black | 48.9 | 65.9 | 53.0 | 45.8 | 37.7 | 35.6 | |
| Non-Hispanic white | 35.1 | 22.0 | 33.2 | 35.2 | 44.9 | 45.6 | |
| BMI, kg/m2 | 30.5±7.5 | 31.8±8.5 | 30.5±7.3 | 30.4±7.8 | 30.0±6.7 | 29.1±6.0 | <0.001 |
| Comorbidities | |||||||
| Prevalent diabetes, % | 9.1 | 18.5 | 8.9 | 5.4 | 7.0 | 3.3 | <0.001 |
| Prevalent hypertension, % | 37.2 | 42.8 | 34.8 | 34.2 | 34.2 | 41.1 | 0.27 |
| SBP, mm Hg | 126.8±17.8 | 127.2±18.0 | 125.9±17.6 | 126.1±17.2 | 127.4±19.2 | 128.1±17.1 | 0.45 |
| DBP, mm Hg | 79.0±9.9 | 79.0±9.6 | 78.9±10.1 | 78.6±9.4 | 79.0±10.7 | 79.9±9.8 | 0.66 |
| Current smoker, % | 25.8 | 27.5 | 28.7 | 25.1 | 23.6 | 23.0 | 0.009* |
| Current alcohol user, % | 71.4 | 66.7 | 72.7 | 72.5 | 74.4 | 71.0 | 0.12* |
| Medications | |||||||
| Diuretics, % | 9.1 | 12.2 | 6.4 | 8.7 | 8.7 | 9.3 | 0.32 |
| ACEI, % | 17.5 | 22.8 | 17.0 | 16.8 | 15.1 | 14.1 | 0.001 |
| ARB, % | 9.5 | 11.1 | 8.6 | 8.5 | 9.4 | 10.4 | 0.73 |
| Dietary supplements, % | 23.7 | 18.7 | 23.0 | 23.4 | 28.5 | 26.7 | 0.001 |
| Laboratory values | |||||||
| Magnesium, mg/dL | 2.1±0.2 | 1.8±0.1 | 2.0±0.0 | 2.1±0.0 | 2.2±0.0 | 2.4±0.1 | |
| eGFR, mL/min/1.73m2 | 99.9±20.7 | 105.5±22.4 | 101.1±20.0 | 98.7±19.8 | 97.7±21.0 | 93.8±17.7 | <0.001 |
| ΔeGFR, mL/min/1.73 m2 per year | −0.7 (−2.4, 0.7) | −1.1 (−3.1,0.5) | −0.8 (−2.5, 0.7) | −0.6 (−2.2, 0.9) | −0.6 (−2.2, 0.6) | −0.5 (−2.0, 1.0) | <0.001 |
| Urine ACR, mg/g | 2.7(1.8, 4.5) | 2.9(1.9, 4.9) | 2.8 (1.8, 4.9) | 2.6 (1.7, 4.6) | 2.7(1.8, 4.1) | 2.5(1.8, 3.9) | 0.009 |
| Albumin, g/dL | 4.0±0.3 | 3.8±0.3 | 4.0±0.3 | 4.0±0.3 | 4.1±0.3 | 4.1±0.3 | <0.001 |
| Glucose, mg/dL | 100.5±37.9 | 113.2±60.6 | 99.9±37.8 | 96.0±23.0 | 96.9±23.1 | 93.2±16.7 | 0.08 |
| Calcium, mg/dL | 9.2±0.4 | 9.2±0.4 | 9.2±0.4 | 9.2±0.4 | 9.3±0.3 | 9.3±0.4 | <0.001 |
| Phosphate, mg/dL | 3.2±0.6 | 3.2±0.6 | 3.2±0.5 | 3.2±0.5 | 3.2±0.6 | 3.2±0.7 | 0.32 |
| Sodium, mEq/L | 137.7±2.4 | 136.9±2.4 | 137.6±2.3 | 137.7±2.3 | 138.2±2.4 | 138.3±2.5 | <0.001 |
| Potassium, mEq/L | 4.3±1.7 | 4.2±1.6 | 4.4±1.4 | 4.3±1.8 | 4.2±2.1 | 4.5±1.6 | <0.001 |
| Bicarbonate, mEq/L | 27.2±2.2 | 26.8±2.2 | 27.1±2.1 | 27.1±2.2 | 27.5±2.1 | 27.7±2.3 | <0.001 |
| iPTH, pg/mL | 37.2(28.3, 49.9) | 35.8 (26.1,49.1) | 38.0 (28.7, 48.6) | 37.2(28.7, 50.2) | 37.1 (29.1, 51.1) | 38.2(29.2, 52.1) | 0.01 |
| Total cholesterol, mg/dL | 180.6±37.8 | 172.9±38.3 | 181.4±36.6 | 181.2±37.1 | 181.3±36.8 | 190.6±38.8 | <0.001 |
| HDL, mg/dL | 50.4±14.6 | 52.1±15.5 | 51.1±14.5 | 50.6±14.5 | 48.1±13.7 | 49.5±14.6 | 0.001 |
| CRP, mg/L | 2.7 (1.1,6.4) | 3.2 (1.0, 8.4) | 2.7 (1.1,6.6) | 2.7 (1.2, 6.7) | 2.2 (0.9, 5.3) | 2.5 (1.1,4.9) | <0.001 |
χ2 Data are presented as mean±SD, median (25th, 75th percentile) or per cent for categorical variables.
eGFR was calculated according to the MDRD study equation. Microalbuminuria was calculated as ACR. Dietary supplements consisted of any combination or single treatment with Mg, calcium, active vitamin D and/or multivitamins. Conversion factors for units: phosphate in mg/dL to mmol/L, ×0.3229; calcium in mg/dL to mmol/L, ×0.2495; cholesterol in mg/dL to mmol/L, ×0.02586; HDL in mg/dL to mmol/L, ×0.0258.
ACEI, ACE inhibitors; ACR, microalbumin/creatinine ratio; ARB, angiotensin II receptor blockers; BMI, body mass index; BP, blood pressure; CRP, C reactive protein; DHS, Dallas Heart Study; eGFR, estimated glomerular filtration rate; HDL, high-density lipoprotein; iPTH, intact parathyroid hormone.