HYPONATREMIA: CLASSIFICATION AND DIAGNOSIS NOAH CARPENTER, MD Dr. Noah Carpenter is a Thoracic and Peripheral Vascular Surgeon. He completed a Bachelor of Science in chemistry and medical school and training at the University of Manitoba. Dr. Carpenter completed surgical residency and fellowship at the University of Edmonton and Affiliated Hospitals in Edmonton, Alberta, and an additional Adult Cardiovascular and Thoracic Surgery fellowship at the University of Edinburgh, Scotland. He has specialized in microsurgical techniques, vascular endoscopy, laser and laparoscopic surgery in Brandon, Manitoba and Vancouver, British Columbia, Canada and in Colorado, Texas, and California. Dr. Carpenter has an Honorary Doctorate of Law from the University of Calgary, and was appointed a Citizen Ambassador to China, and has served as a member of the Native Physicians Association of Canada, the Canadian College of Health Service Executives, the Science Institute of the Northwest Territories, the Canada Science Council, and the International Society of Endovascular Surgeons, among others. He has been an inspiration to youth, motivating them to understand the importance of achieving higher education. ABSTRACT Hyponatremia is the most common disorder of body fluid and electrolyte balance, which can lead to a wide range of clinical symptoms that can be severe or even fatal. Many different conditions can lead to hyponatremia, imposing on health clinicians a high need to recognize the signs and symptoms, and to administer immediate treatment according to the latest medical research and guidelines. 1 NurseCe4Less.com Policy Statement This activity has been planned and implemented in accordance with the policies of NurseCe4Less.com and the continuing nursing education requirements of the American Nurses Credentialing Center's Commission on Accreditation for registered nurses. Continuing Education Credit Designation This educational activity is credited for 2.5 hours at completion of the activity. Statement of Learning Need The degree of severity and causes of hyponatremia are often underestimated by health clinicians. Clinicians need to know how to recognize hyponatremia and to distinguish it from false hyponatremia. The conditions that can lead to hyponatremia, how to recognize the conditions, and the proper administration of treatment are important clinical considerations. The latest research and guidelines for recognition and treatment of hyponatremia are key to planning a patient’s course of care. Course Purpose To provide health clinicians with knowledge of the conditions that can lead to hyponatremia, of how to recognize such conditions, and of the proper treatment. Target Audience Advanced Practice Registered Nurses, Registered Nurses, and other Interdisciplinary Health Team Members. Disclosures Noah Carpenter, MD, William Cook, PhD, Douglas Lawrence, MA, Susan DePasquale, MSN, FPMHNP-BC – all have no disclosures. There is no commercial support. 2 NurseCe4Less.com Self-Assessment of Knowledge Pre-Test: 1. Hyponatremia is generally defined as a a. high or low blood sodium level. b. high calcium concentration. c. low blood sodium level or serum sodium concentration. d. low potassium level. 2. ___________ hyponatremia is defined as a biochemical finding of a serum sodium concentration <120 mmol/l. a. Severe b. Moderate c. Pseudo d. Mild 3. ______________ comprise the majority of patients who are diagnosed with hyponatremia. a. Males b. Elderly patients c. Adolescents d. Hospitalized patients 4. Acute hyponatremia exists when the condition is documented for a period of a. a week. b. 72 hours. c. at least 48 hours. d. less than 48 hours. 5. Hyponatremia is classified as _____________ if a person’s body fluid volume is low. a. asymptomatic b. euvolemic c. hypervolemic d. hypovolemic 3 NurseCe4Less.com Introduction Hyponatremia is the most frequent electrolyte disorder encountered by health clinicians. In hospitalized patients, the most common electrolyte disorder is hyponatremia, and the incidence of hyponatremia is significant. It can lead to symptoms that can range from mild to severe, or even fatal. The severity and causes of hyponatremia are often underestimated by health clinicians. The conditions that can lead to hyponatremia, how to recognize the conditions, and the proper administration of treatment are discussed in the following sections. The latest research and guidelines for recognition and treatment of hyponatremia are also raised. Definition and Etiology of Hyponatremia Hyponatremia is the most common electrolyte disorder in hospitalized patients associated with increased mortality and morbidity. It is generally defined as a low blood sodium level or serum sodium concentration < 136 mmol/l.1 Mild hyponatremia is defined as a serum sodium concentration between 130 to 134 mEq/L, moderate hyponatremia is defined as a serum sodium concentration between 120 to 129 mEq/L mmol/l, and severe hyponatremia is defined as a serum sodium concentration of < 120 mEq/L.2 The prevalence of hyponatremia is reportedly as high as 30% depending on the criteria for its diagnosis.3 The clinical setting and the patient population are relevant to hyponatremia prevalence, and the condition correlates with significant morbidity and mortality and will vary depending upon the disease states and medical conditions occurring when hyponatremia is diagnosed. Serum sodium levels that are significantly low or fluctuating can lead to serious outcomes, even death.3 Complications of hyponatremia are preventable if the condition is diagnosed early and appropriately treated. The cause of hyponatremia is important to diagnose correctly. If the etiology is not correctly understood the treatment may lead to worse clinical outcomes. There are multiple causes for decreased serum sodium levels. In patients with a diagnosis of the syndrome of inappropriate antidiuretic 4 NurseCe4Less.com hormone (SIADH) secretion and co-occurring gastrointestinal symptoms, i.e., nausea and vomiting, volume replacement may be a necessary priority of treatment. Clinicians should always keep in mind that the indiscriminate use of large volumes of intravenous normal saline could lead to worsened serum sodium levels in cases of elevated vasopressin levels.3 The incidence of hyponatremia depends in large part on the patient population. Clinical symptoms vary from asymptomatic to seizures and coma. It is important to determine the prevalence of this condition since multiple new drugs exist and there are clinical determinants leading to hyponatremia.3 Moderate-to-severe hyponatremia, in particular with rapid onset, corresponds with significant morbidity and mortality. There are many underlying disease states and multiple causes associated with hyponatremia.3 Individuals who have sodium levels that shift suddenly or are severely hyponatremic must be treated immediately to avoid serious health outcomes and death. Treatment outcomes depends on whether or not the affected person has co-occurring health issues, and the severity of clinical symptoms. A hyponatremic person may be asymptomatic or show severe symptoms, including seizures and coma.3 Medical professionals will need to determine the underlying cause of hyponatremia, such as a clinical condition or medication- induced etiology. In hospitalized patients the prevalence of hyponatremia has reportedly reached as high as 30% based upon diagnostic criteria, patient population and clinical setting.3 However, in some studies hyponatremia is not found to be as high in hospitalized patients as in earlier reports, which is believed to be due to improved surveillance through laboratory testing of patients on diuretics or drugs known to cause hyponatremia, i.e., those that act on the central nervous system (CNS).3 The elderly, those individuals 65 or greater years of age, comprise the majority of patients who are diagnosed with hyponatremia. Elderly who are prescribed diuretic therapy are at higher risk of becoming hyponatremic.3 However, in younger patients a finding of end stage renal disease (ESRD) was 5 NurseCe4Less.com the primary underlying condition related to the development of hyponatremia. In both elderly and young individuals, hyponatremia is typically a secondary condition.3 Diuretic medication is a well-known cause of hyponatremia therefore patient education of the signs and symptoms of low sodium levels and vigilant monitoring of blood sodium levels, patient fluid intake and conditions that could lead to electrolyte disturbances, such as vomiting and diarrhea, is essential to avoid complications related to hyponatremia.3 Hyponatremia occurs more frequently in females than males.4 People who are depressed and prescribed antidepressant medication, selective serotonin reuptake inhibitors (SSRIs) have been identified with hyponatremia.4 As noted previously, there are multiple factors that can lead to hyponatremia, such as excessive fluid intake.4 Clinicians need to be cautious when diagnosing the cause of hyponatremia and when selecting recommended treatment to prevent a worse complication related to hyponatremia. Classification of Hyponatremia A classification system of hyponatremia should be consistent and helpful for both differential diagnosis and treatment. Classification of hyponatremia is according to various factors, and clinicians should recognize that each classification has advantages and disadvantages depending on clinical settings and situations. Clinicians should also bear in mind that differential diagnosis of hyponatremia can be