Hypernatremia

Question 1

Q: What is hypernatremia?

Answer 1

A: A condition characterized by a higher than normal concentration of sodium in the blood, above 145 milliequivalents per liter.

Question 2

Q: What does hypernatremia actually indicate about water levels in the body?

Answer 2

A: It indicates too little water in the extracellular compartment.

Question 3

Q: How is total body water distributed in the body?

Answer 3

A: It is distributed in the intracellular compartment (inside the cells) and the extracellular compartment (outside the cells).

Question 4

Q: What is the normal osmolality range for both intracellular and extracellular compartments?

Answer 4

A: Normally between 275 and 290 milliosmoles per kilogram.

Question 5

Q: How can serum osmolality be calculated?

Answer 5

A: Using the formula: 2 × [Na+] + [glucose]/18 + BUN/2.8.

Question 6

Q: What are some solutes that can’t freely cross cell membranes and generate osmotic pressure?

Answer 6

A: Sodium and glucose.

Question 7

Q: What typically causes hypernatremia?

Answer 7

A: Either gaining more sodium than water or losing more water than sodium.

Question 8

Q: What can cause sodium gain leading to hypernatremia?

Answer 8

A: Iatrogenic overload (e.g., hypertonic saline or sodium bicarbonate solutions) or salt poisoning.

Question 9

Q: What are the common clinical sources of unreplaced water losses leading to hypernatremia?

Answer 9

A: Skin, gastrointestinal, and urinary losses.

Question 10

Q: How does the body usually compensate for high blood osmolality?

Answer 10

A: Through thirst (regulated by the hypothalamus) and secretion of antidiuretic hormone (ADH) by the pituitary.

Question 11

Q: What are some groups more at risk of developing hypernatremia due to lack of access to water?

Answer 11

A: Infants, individuals in the ICU, and the elderly in nursing homes.

Question 12

Q: What neurological symptoms can acute hypernatremia cause?

Answer 12

A: Lethargy, weakness, altered mental status, irritability, seizures, and coma.

Question 13

Q: What condition can result from both abolished thirst and decreased ADH secretion?

Answer 13

A: Adipsic diabetes insipidus.

Question 14

Q: What urine osmolality value suggests kidneys are retaining more water in response to high serum sodium?

Answer 14

A: Higher than 600 milliosmoles per kilogram.

Question 15

Q: What condition can result from both abolished thirst and decreased ADH secretion?

Answer 15

A: Adipsic diabetes insipidus.

Question 16

Q: What urine osmolality value suggests kidneys are retaining more water in response to high serum sodium?

Answer 16

A: Higher than 600 milliosmoles per kilogram.

Question 17

Q: What does a urine osmolality less than 300 milliosmoles per kilogram suggest?

Answer 17

A: Diabetes insipidus.

Question 18

Q: How do you differentiate between central and nephrogenic diabetes insipidus?

Answer 18

A: By administering exogenous ADH and observing urine osmolality response.

Question 19

Q: What formula is used to estimate the total water deficit for treating hypernatremia?

Answer 19

A: Total body water × [(serum sodium / 140) - 1].

Question 20

Q: How should sodium be corrected to avoid the risk of cerebral edema?

Answer 20

A: By a maximum of 10 milliequivalents per liter per day.

Question 21

Q: What treatment is recommended for individuals with central diabetes insipidus?

Answer 21

A: Lifelong treatment with desmopressin.

Question 22

Q: How can urine output be controlled in individuals with nephrogenic diabetes insipidus?

Answer 22

A: With a low-salt, low-protein diet, and diuretics like hydrochlorothiazide or amiloride.

Question 23

Q: What are the summary points for hypernatremia diagnosis and treatment?

Answer 23

A: Sodium concentration >145 mEq/L, determine cause based on volume status and urine osmolality, treat with 5% dextrose or water, and correct sodium gradually.