Hypochloraemia as a predictor of developing hyponatraemia and poor outcome in acute heart failure patients.

AIMS: Heart failure (HF) is a major public health issue currently affecting more than 23 million patients worldwide. Hyponatraemia has been shown to be a predictor of poor outcome in patients with acute and chronic HF. Therefore, we aimed at finding a marker for early detection of patients at risk for developing hyponatraemia. To this end, the present study investigated the relationship between initial serum chloride and follow-up sodium levels in acute heart failure (AHF) patients. METHODS AND RESULTS: The present study was performed as a prospective, single-centre, observational research with a total of 152 hospitalised AHF patients. Compared to patients with initial normochloraemia, patients with initial hypochloraemia had a statistically significantly higher incidence of hyponatraemia after a 3-month follow-up [P<0.001; odds ratio (OR)=27.08, CI: 4.3-170.7]. A similar finding was obtained upon exclusion of patients with initial hyponatraemia with Fishers test [P=0.034; odds ratio (OR)=15.5, CI:1.7-140.6]. Binary logistic regression revealed a significantly increased in-hospital mortality in the hypochloraemic/normonatriaemic (OR=4.08, CI 1.08-15.43, P=0.039), but not in the hypochloraemic/hyponatraemic, normochloraemic/hyponatraemic or normonatriaemic/normochloraemic patients. Ejection fraction (EF) at admission was significantly higher in hypochloraemic/normonatriaemic, compared to normonatriaemic/normochloraemic patients, but similar to EF in both hypochloraemic/hyponatraemic and normochloraemic/hyponatraemic patients. The N-terminal precursor Brain Natriuretic Peptide (Nt-proBNP) levels at admission were significantly lower in hypochloraemic/normonatriaemic compared to hypochloraemic/hyponatraemic and normonatriaemic/normochloraemic patients, respectively. CONCLUSION: The data show that initial low serum chloride concentration is predictive of developing hyponatraemia and associated with increased in-hospital mortality in AHF patients.

Comparison of digoxin concentration in plastic serum tubes with clot activator and heparinized plasma tubes.

INTRODUCTION: Sample type recommended by the manufacturer for the digoxin Abbott assay is either serum collected in glass tubes or plasma (sodium heparin, lithium heparin, citrate, EDTA or oxalate as anticoagulant) collected in plastic tubes. In our hospital samples are collected in plastic tubes. Our hypothesis was that the serum sample collected in plastic serum tube can be used interchangeably with plasma sample for measurement of digoxin concentration. Our aim was verification of plastic serum tubes for determination of digoxin concentration. MATERIALS AND METHODS: Concentration of digoxin was determined simultaneously in 26 venous blood plasma (plastic Vacuette, LH Lithium heparin) and serum (plastic Vacuette, Z Serum Clot activator; both Greiner Bio-One GmbH, Kremsmünster, Austria) samples, on Abbott AxSYM analyzer using the original Abbott Digoxin III assay (Abbott, Wiesbaden, Germany). Tube comparability was assessed using the Passing Bablok regression and Bland-Altman plot. RESULTS: Serum and plasma digoxin concentrations are comparable. Passing Bablok intercept (0.08 [95% CI = -0.10 to 0.20]) and slope (0.99 [95% CI = 0.92 to 1.11]) showed there is no constant or proportional error. CONCLUSION: Blood samples drawn in plastic serum tubes and plastic plasma tubes can be interchangeably used for determination of digoxin concentration.