Hypernatremia Flashcards
Q: What is hypernatremia?
A: A condition characterized by a higher than normal concentration of sodium in the blood, above 145 milliequivalents per liter.
Q: What does hypernatremia actually indicate about water levels in the body?
A: It indicates too little water in the extracellular compartment.
Q: How is total body water distributed in the body?
A: It is distributed in the intracellular compartment (inside the cells) and the extracellular compartment (outside the cells).
Q: What is the normal osmolality range for both intracellular and extracellular compartments?
A: Normally between 275 and 290 milliosmoles per kilogram.
Q: How can serum osmolality be calculated?
A: Using the formula: 2 × [Na+] + [glucose]/18 + BUN/2.8.
Q: What are some solutes that can’t freely cross cell membranes and generate osmotic pressure?
A: Sodium and glucose.
Q: What typically causes hypernatremia?
A: Either gaining more sodium than water or losing more water than sodium.
Q: What can cause sodium gain leading to hypernatremia?
A: Iatrogenic overload (e.g., hypertonic saline or sodium bicarbonate solutions) or salt poisoning.
Q: What are the common clinical sources of unreplaced water losses leading to hypernatremia?
A: Skin, gastrointestinal, and urinary losses.
Q: How does the body usually compensate for high blood osmolality?
A: Through thirst (regulated by the hypothalamus) and secretion of antidiuretic hormone (ADH) by the pituitary.
Q: What are some groups more at risk of developing hypernatremia due to lack of access to water?
A: Infants, individuals in the ICU, and the elderly in nursing homes.
Q: What neurological symptoms can acute hypernatremia cause?
A: Lethargy, weakness, altered mental status, irritability, seizures, and coma.
Q: What condition can result from both abolished thirst and decreased ADH secretion?
A: Adipsic diabetes insipidus.
Q: What urine osmolality value suggests kidneys are retaining more water in response to high serum sodium?
A: Higher than 600 milliosmoles per kilogram.
Q: What condition can result from both abolished thirst and decreased ADH secretion?
A: Adipsic diabetes insipidus.
Q: What urine osmolality value suggests kidneys are retaining more water in response to high serum sodium?
A: Higher than 600 milliosmoles per kilogram.
Q: What does a urine osmolality less than 300 milliosmoles per kilogram suggest?
A: Diabetes insipidus.
Q: How do you differentiate between central and nephrogenic diabetes insipidus?
A: By administering exogenous ADH and observing urine osmolality response.
Q: What formula is used to estimate the total water deficit for treating hypernatremia?
A: Total body water × [(serum sodium / 140) - 1].
Q: How should sodium be corrected to avoid the risk of cerebral edema?
A: By a maximum of 10 milliequivalents per liter per day.
Q: What treatment is recommended for individuals with central diabetes insipidus?
A: Lifelong treatment with desmopressin.
Q: How can urine output be controlled in individuals with nephrogenic diabetes insipidus?
A: With a low-salt, low-protein diet, and diuretics like hydrochlorothiazide or amiloride.
Q: What are the summary points for hypernatremia diagnosis and treatment?
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.
