Endocrine Abstracts

Introduction: Hyponatremia is the most common electrolyte disorder and it affects approximately 5% of adults and 35% of hospitalized patients. Diagnostic and/or therapeutic challenge is given. It is defined by a serum sodium concentration of less than 136 mmol/l. Symptoms of hyponatremia range from mild and nonspecific to severe and life-threatening. Hyponatremia is classified as mild, moderate and severe and may be acute or chronic. Mortality and morbidity are significantly increased in patients with hyponatremia.

Material and Methods: About 46.700 medical records between Augusts 2012 and 2022 were screened in an outpatient endocrine department. In 136 cases hyponatremia was found with an overall prevalence of 0.3%. Due to missing data, 40 patients had to be excluded from statistical analysis. Patients were analyzed with respect to age, sex, BMI, pre-existing conditions, medication, type and degree of hyponatremia and random finding of hyponatremia. Symptoms, therapy and serum sodium levels before and after treatment were assessed. To evaluate the prevalence of hyponatremia in the outpatient setting and identify specific risk factors.

Results: Females (79.2%) were more affected than males. Afflicted patients had a mean age of 71 years. With respect to severity, 19.7 % of patients had mild, 43.9% moderate and 36.4% severe hyponatremia. 97% of patients complained symptoms like nausea, vomiting, fatigue and dizziness. 59.1% of patients were diagnosed with SIADH with 6.1% also having a post op SIADH. In 25.8% cases the origin could not be clarified in the course of the disease. Hypervolemic or hypovolemic hyponatremia was found in 9% of the patients. Regarding known risk factors such as diuretic use, previous cardiological disease or nephrological preconditions we found no notable differences compared to patients without hyponatremia. Although women are more likely to develop hyponatremia, gender did not seem to play a role in the severity of the disease. The presence of incidental finding probably had an influence on the degree of hyponatremia. Conventional treatment (drinking restriction, adaptation of the medication schedule, modification of diuretics and/or tolvaptan therapy) led to a meaningful improvement in 74% of patients.

Conclusion: The number of outpatient cases was noticeably lower than the average number of hospitalized patients. However, in almost 25% of the affected patients, the origin could not be found. Guidelines and therapies used in the hospital also showed a noticeable improvement in this patient group. We hypothesize, that quick treatment may reduce the mortality and morbidity of outpatients.