Is increased subjective thirst associated with greater interdialytic weight gains, extracellular fluid and dietary sodium intake?

Background: Some previous studies have reported an effect of increasing subjective thirst and interdialytic weight gains (IDWG), and that this may be influenced by nonadherence to dietary sodium restrictions, whereas others reported no such association. As such we wished to review the effect of self-reported thirst on IDWGs and dietary sodium intake.Methods: Dialysis patients were asked to complete visual analogues thirst, distress thermometer (DT) scores and complete a sodium food frequency questionnaire (SFFQ). IDWG and pre and post dialysis volumes were measured with multifrequency bioelectrical impedance.Results: One hundred and eleven patients completed the questionnaires and had bioimpedance measurements: 63% male, mean age 63.8 +/- 16.1 years, 33% diabetic with a median thirst score 3 (0-5) and SFFQ 52.0 +/- 18, and IDWG 2.1 +/- 1.3%. Thirst was associated with DT (r= 0.28, p= 0.004) and negatively with age (r= -0.31, p< 0.001), but not SFFQ, IDWG, extracellular water, or dialysate sodium, or dialysate to plasma gradient. Patients with higher thirst scores were younger (58.0 +/- 15.2 vs. 69.4 +/- 15.0 years, p< 0.001) with higher DT scores (5 [2-7] vs. 2 [0-5], p< 0.001). On multivariate logistic analysis, only age was associated with self-reported thirst (odds ratio 0.95, 95% confidence limits 0.92-0.98, p< 0.001).Conclusion: We found that subjective thirst was greater for younger patients and those who reported higher levels of distress, but no association with IDWGs, dietary sodium intake, or dialysate sodium. However, most of our patients followed the dietary advice, as evidenced by the low SFFQ scores and % IDWGs. Whether thirst increases distress or distress increases subjective thirst remains to be determined.