Table 2.
Kidney function, metabolic parameters, and acid-base status before the furosemide/fludrocortisone test
| Characteristics | Normal Response to the Test | Abnormal Response to the Test | P |
|---|---|---|---|
| Number of participants | 12 | 13 | |
| Blood | |||
| eGFR (ml/min per 1.73 m2) | 131 (124–140) | 114 (93–127) | 0.03a |
| Plasma sodium (mEq/L) | 140 (138–141) | 138 (138–140) | 0.22 |
| Plasma potassium (mEq/L) | 3.9 (3.6–4.1) | 4.1 (3.8–4.6) | 0.06 |
| Plasma chloride (mEq/L) | 107 (105–108) | 107 (105–108) | 0.80 |
| Plasma anion gap (mEq/L)b | 14 (12–16) | 13 (13–15) | 0.78 |
| Serum ionized calcium (md/dl)c | 4.93 (4.85–5.00) | 4.97 (4.85–5.17) | 0.45 |
| Plasma phosphate (mg/dl)d | 3.6 (3.1–3.9) | 3.7 (3.3–3.8) | 0.95 |
| Plasma magnesium (mg/dl)e | 1.9 (1.8–2.0) | 1.7 (1.6–2.0) | 0.22 |
| Plasma glucose (mg/dl)f | 89 (76–93) | 86 (80–91) | 0.93 |
| Blood venous pH (UpH) | 7.39 (7.37–7.40) | 7.38 (7.36–7.39) | 0.28 |
| Blood venous pCO2 (mm Hg) | 427 (39–43) | 39 (36–42) | 0.08 |
| Blood venous bicarbonate (mEq/L) | 24 (23–25) | 23 (20–24) | 0.02a |
| Plasma renin (mU/L) | 20 (11–44) | 19 (6–42) | 0.72 |
| Plasma aldosteroneg | 0.11 (0.07–0.16) | 0.13 (0.08–0.23) | 0.53 |
| Plasma osmolality (mOsm/kg water) | 295 (293–296) | 296 (294–301) | 0.32 |
| Urine | |||
| Daily urinary sodium excretion (mEq/d)d | 135 (61–152) | 112 (86–172) | 0.65 |
| Daily urinary potassium excretion (mEq/d)h | 39 (26–45) | 31 (22–42) | 0.38 |
| Daily urinary chloride excretion (mEq/d)h | 127 (73–153) | 103 (74–163) | 0.61 |
| Daily urinary creatinine excretion (mg/kg per day)h,i | 19.2 (14.7–22.6) | 14.7 (13.6–19.2) | 0.14 |
| Daily urinary calcium excretion (mg/d)c | 51 (34–86) | 38 (11–98) | 0.51 |
| Daily urinary phosphate excretion (mg/d)d | 543 (381–651) | 443 (273–521) | 0.27 |
| Daily urinary magnesium excretion (mg/d)e | 59 (43–83) | 57 (60–78) | 0.86 |
| Daily urinary uric acid excretion (mg/d)h,j | 471 (437–622) | 437 (303–588) | 0.31 |
| Fasting urine pH (UpH) | 5.45 (5.26–5.71) | 5.76 (5.52–6.40) | 0.02a |
| Fasting urinary net acid excretion (mEq/min) | 29 (19–36) | 10 (7–26) | 0.02a |
| Fasting urinary NH4+ (mEq/L) | 21 (17–35) | 12 (7–15) | 0.006a |
| Fasting urinary NH4+ (mEq/min) | 23 (14–26) | 10 (7–17) | 0.01a |
| Fasting urinary titratable acid excretion (mEq/min) | 6.9 (5.5–13.2) | 5.0 (0.7–12.5) | 0.17 |
| Daily urinary net acid excretion (mEq/d)h | 38 (32–42) | 259 (14–35) | 0.01a |
| Daily urinary NH4+ excretion (mEq/d)h | 25 (23–32) | 17 (13–22) | <0.001a |
| Daily urinary anion gap (mEq/d)h | 22 (9–32) | 33 (29–39) | 0.04a |
| Urinary protein/creatinine ratio (mg/mmol) | 16 (9–18) | 15 (11–61) | 0.49 |
| Urinary albumin/creatinine ratio (mg/mmol) | 4 (1–4) | 3 (1–35) | 0.79 |
| Daily glycosuriak | 0 (0) | 0 (0) | 0.99 |
| Fasting urine osmolality (mOsm/kg water) | 438 (422–452) | 383 (359–434) | 0.05 |
| Daily urine output (L/d)h | 1.67 (1.42–1.97) | 1.51 (1.10–2.50) | 0.92 |
Data are expressed as n (%), mean (±SD), or median (interquartile range). P values represent the comparison between participants with an abnormal response to the test and the participants with a normal response to the test. All plasma parameters were assessed in fasting conditions, and 24-h urine samples were collected the day before the test. Urinary fasting parameters are based on fasting morning urine collected upon arrival of the patient in the Physiology Department at 8 am after 12 h of strict fasting and correspond to second fasting morning urine. pCO2, partial pressure of carbon dioxide; NH4+, ammonium ions.
P<0.05.
Plasma anion gap=(sodium ions + potassium ions) − (chloride ions − bicarbonate ions). Normal range: 12–20 mEq/L.
To convert calcium concentrations to mmol/L, divide values in mg/dl by 4; to get values in mmol/d, divide values in mg/d by 40.
To convert phosphate concentrations to mmol/L, divide values in mg/dl by 3.1; to get values in mmol/d, divide values in mg/d by 31.
To convert magnesium concentrations to mmol/L, divide values in mg/dl by 2.43; to get values in mmol/d, divide values in mg/d by 24.3.
To convert glucose concentrations to mmol/L, multiply values in mg/dl by 0.055.
Three different assays were used to measure plasma aldosterone concentration during the study so results are reported as the ratio to the upper limit of the normal range.
Data missing for four participants.
To get creatinine values in mmol/kg per day, divide values in mg/kg per day by 113.12.
To get uric acid excretion values in mmol/d, divide values in mg/d by 168.11.
Data missing for eight participants. Glycosuria was defined as >0.3 mmol/d.