HYPONATREMIA

Is a condition when Sodium (Na) levels is less than 135 milliequivalents of solute per litre (meq/L).

Remember that Na is the must abundant electrolyte in the extracellular fluids. It is a good indicator for the body water balance.

"Water Follows Sodium"

This helps you to understands when there is changes in shift due to inadequate amount of sodium. The other key point to remember about sodium is;

"The Kidney is responsible for the excreting the sodium from the body"

So, any changes in kidneys are going to affect your Na balance. So, here is a case;

We have someone who have a very fatigue look, and overall body appearance in terms of hydration were very depending on - if we talking about a depletional or dilutional hypernatremia. There's a confusion, and we also see a sense of noxious, not hungry and sometimes vomiting, which again when you think about what happens about fluids during vomiting is a problems. There's also muscle cramps, weakness, and changes in blood pressure - which again depends on depletional or dilutional, which may end up being increased or decreased.

Dilutional hyponatremia

There is excess of water in the systems. You have a dilutional low sodium level. So, so much water in ratio of to the sodium that produces the dilutional hyponatremia. The situation here would be a high BP, weight gain, typically a bounding, rapid pulse and a high urine specificity gravity.

Depletionl Hyponatremia

This is often seen with hypobulimia - in other words, there is so much fluids loss, that it have been occurs in corresponding with sodium loss. The patient have a low BP, dry skin, and  a low urine specificity gravity. So, they really excreting a lot of fluids - eg vomiting.

So, two different causes that produce the same imbalance of hyponatremia