Final answer:
Hyponatremia occurs when sodium levels fall below 135 mEq/L and can be caused by excessive sweating, vomiting, diarrhea, diuretics, diabetes, acidosis, and fluid imbalances due to conditions like congestive heart failure.
Step-by-step explanation:
Regarding the question which statement is true about hyponatremia:
Hyponatremia occurs when sodium levels in the blood drop below 135 mEq/L. It is typically associated with excess water in the body, which dilutes the sodium concentration. While inadequate sodium intake can contribute to hyponatremia, it is not commonly caused by this alone. On the contrary, conditions such as excessive sweating, vomiting, or diarrhea can lead to an abnormal loss of sodium. Additionally, the use of diuretics, and certain medical conditions like diabetes and acidosis (metabolic acidosis or diabetic ketoacidosis) can also contribute to the loss. A relative decrease in blood sodium can happen due to imbalances in fluid compartments or from water retention related to conditions like edema or congestive heart failure. This swelling of cells, especially red blood cells and neurons, caused by the dilution of extracellular fluid (ECF), can lead to severe health issues, including brain damage.