Endocrine Abstracts

Introduction: Onset of hyperkalemia has previously been reported during the administration of hypertonic resuscitation solutions. Since the hypertonic saline infusion test has recently been validated for the diagnosis of diabetes insipidus, we aimed to investigate the course of plasma potassium levels during the test.

Material and Methods: Data of 144 patients undergoing osmotic stimulation with hypertonic saline infusion at 11 tertiary medical centres in Germany, Switzerland and Brazil from July 2013 to June 2017 were analyzed. Patients received a 250 ml bolus of 3% NaCl solution, followed by 0.15 ml/min/kg body weight continuously infused targeting a plasma sodium level of 150 mmol/l. Blood samples and clinical data were collected every 30 minutes. The primary outcome of this secondary analysis was percentage of patients developing hyperkalemia.

Results: Of the 144 patients, 9.7% (n =14) developed hyperkalemia of >5 mmol/l, 2% (n = 3) >5.5 mmol/l and 0.7% (n = 1) > 6 mmol/l. The majority of the affected patients were diagnosed with primary polydipsia (86% >5 mmol/l and 100% in the other 2 groups). Hyperkalemia was transient and not clinical symptomatic in all patients. Onset of hyperkalemia was related with duration of the infusion test, showing a peak after 120 minutes. A plasma sodium <146 mmol/l at 30-minute test duration was associated with development of hyperkalemia >5 mmol/l (OR 5.5, 95% CI 1.6–25.4, P = 0.01). No association was found with plasma chloride or pH levels.

Conclusion: Patients with primary polydipsia are at risk to develop hyperkalemia while undergoing hypertonic saline infusion test, although its incidence is low. Particular attention should be paid if test duration exceeds 90-minutes and in patients with a plasma sodium <146 mmol/l after 30 minutes.