Osmolality

Every question here, with the answer

1. A client with poorly controlled diabetes has a very high blood glucose level. Which change should the nurse expect in the client's cells?

   1. Water moves into the cells and they swell.
   2. The cells gain sodium and burst.
   3. There is no net movement of water.
   4. Water moves out of the cells and they shrink.

   Answer: Water moves out of the cells and they shrink.

   High blood glucose raises solute concentration and makes the blood hypertonic compared with the cytoplasm, so water moves out of the cells and they shrink. Swelling happens with hypotonicity, and no net movement happens only with isotonicity.

2. A nurse is assessing a client with a high serum osmolality. Which findings should the nurse watch for? Select all that apply.

   1. Decreasing level of consciousness
   2. Hair loss
   3. Seizures
   4. Increased appetite
   5. Irritability

   Answer: Decreasing level of consciousness, Seizures, Irritability

   Hyperosmolality can cause neurologic signs such as irritability, seizures and, in severe cases, coma, as well as cardiovascular impairment. Appetite and hair changes are not described.

3. A client drank a very large amount of water in a short time and now has a low serum osmolality. What should the nurse understand about this state?

   1. It can cause neurologic signs and even coma if not corrected.
   2. It causes the cells to shrink.
   3. It only affects the urine, not the blood.
   4. It is harmless because the kidneys always correct it.

   Answer: It can cause neurologic signs and even coma if not corrected.

   Excessive water intake is a cause of hypoosmolality, which can cause neurologic signs and even coma if not corrected. It lowers solute concentration, so cells swell rather than shrink.

4. Which factors can cause hypoosmolality? Select all that apply.

   1. Excessive water intake
   2. Certain drugs
   3. Hormonal dysregulation of water balance
   4. Dehydration
   5. Disorders affecting the kidneys

   Answer: Excessive water intake, Certain drugs, Hormonal dysregulation of water balance, Disorders affecting the kidneys

   Hypoosmolality can be caused by excessive water intake, certain drugs, kidney disorders and hormonal dysregulation of water balance. Dehydration raises solute concentration and is a cause of hyperosmolality.

5. A student asks the nurse what an isotonic solution does to a cell. Which answer is correct?

   1. It causes no net movement of water into or out of the cell.
   2. It pulls water out of the cell.
   3. It pushes water into the cell.
   4. It raises the solute concentration inside the cell.

   Answer: It causes no net movement of water into or out of the cell.

   An isotonic solution has the same tonicity as the cytoplasm, so solutes are balanced and there is no net movement of water. Water leaves the cell with a hypertonic solution and enters it with a hypotonic one.

6. Which statement about osmolality and tonicity is accurate?

   1. Tonicity describes the ability of a solution to make a cell gain or lose water.
   2. Tonicity is measured only in urine.
   3. Osmolality is measured per liter of solvent.
   4. They are two names for the same measurement.

   Answer: Tonicity describes the ability of a solution to make a cell gain or lose water.

   Osmolality and tonicity are related but not the same: tonicity is the ability of a solution to make a cell gain or lose water, relative to the cytoplasm. Osmolality is per kilogram of solvent; per liter is osmolarity.