[IEMR10-11]Problems in Neuroendocrinology and Electrolytes Flashcards
Autoimmune polyglandular disorder(APS) type 2 is characterized by what multi-organ involvement?(2 points)
Adrenal insufficiency and autoimmune thyroid disease
APS type 3 is characterized by what multi-organ involvement?
An autoimmune thyroid disease without adrenal insufficiency
A definite diagnosis of isolated ACTH deficiency requires what?
Low or absent ACTH upon CRH challenge
CASE - A healthy 24-year-old woman was involved in an automobile accident, and sustained a fracture of her jaw, multiple facial bone fractures, and a brief loss of consciousness. In the emergency department, and IV infusion of 5% dextrose in 0.45% normal saline at 125 mL/hr was started. Twelve hours after admission to the hospital, she is awake and alert, but has difficulty talking and swallowing becuase of her injuries, and she complained of extreme thirst. Her urine output was 500-600 mL/hr. Laboratory studies showed a serum sdoium concentration of 156 mEq/L with a plasma osmolality of 320 mOsm/kg. Her urine osmolality ws 65 mOsm/Kg. What is the most likely diagnosis?
This is likely DIABETES INSIPIDUS (lack of ADH or lack of ADH actions). DI occurs in two forms - central and nephrogenic. Central DI is caused by damage to the hypothalamus, the posterior pituitary, or the connection between them - usually from surgery, tumor, infection, or (as in this case) head injury.
Whatever the cause of central DI, the lesion disrupts the release of ADH – without ADH the body is unable to reabsorb solute-free water in the distal tubule and collecting duct.
Nephrogenic DI, on the other hand, usually occurs as a result of an inherited defect but can also occur as a side effect of drugs (such as lithium or amphotericin B), or in association with polycystic kidney disease.
CASE - A healthy 24-year-old woman was involved in an automobile accident, and sustained a fracture of her jaw, multiple facial bone fractures, and a brief loss of consciousness. In the emergency department, and IV infusion of 5% dextrose in 0.45% normal saline at 125 mL/hr was started. Twelve hours after admission to the hospital, she is awake and alert, but has difficulty talking and swallowing because of her injuries, and she complained of extreme thirst. Her urine output was 500-600 mL/hr. Laboratory studies showed a serum sodium concentration of 156 mEq/L with a plasma osmolality of 320 mOsm/kg. Her urine osmolality ws 65 mOsm/Kg.
What is the usual osmoregulatory response to hypernatremia?
Normal response to hypernatremia is renal water conservation (via ADH) and sensation of thirst. But, this patient is poyuric (not oligouric) reflecting a defect in the kidneys’ ability appropriately concentrate the urine. She is complaining of thirst so this is not the issue.
CASE - A healthy 24-year-old woman was involved in an automobile accident, and sustained a fracture of her jaw, multiple facial bone fractures, and a brief loss of consciousness. In the emergency department, and IV infusion of 5% dextrose in 0.45% normal saline at 125 mL/hr was started. Twelve hours after admission to the hospital, she is awake and alert, but has difficulty talking and swallowing because of her injuries, and she complained of extreme thirst. Her urine output was 500-600 mL/hr. Laboratory studies showed a serum sodium concentration of 156 mEq/L with a plasma osmolality of 320 mOsm/kg. Her urine osmolality ws 65 mOsm/Kg.
What other conditions should be included in a differential diagnosis for polyuria?
Polyuria can be due to a number of conditions - excessive water intake (primary polydipsia with secondary polyuria - psychogenic polydipsia) or excessive renal water loss (remember that whenever the kidney loses solute there will be poyuria). Urine osmolarilty is used to distinguish betwee excessive intake and excessive water loss.
Water diuresis, as in DI, is defined by a urine osmolaity less than 150 mOsm/kg.
Osmotic diuresis, as in diuretic-induced polyuria or the polyuria of hyperglycemia or hypercalcemia, is defined by a urine ismolality > 300 mOsm/Kg.
CASE - A healthy 24-year-old woman was involved in an automobile accident, and sustained a fracture of her jaw, multiple facial bone fractures, and a brief loss of consciousness. In the emergency department, and IV infusion of 5% dextrose in 0.45% normal saline at 125 mL/hr was started. Twelve hours after admission to the hospital, she is awake and alert, but has difficulty talking and swallowing because of her injuries, and she complained of extreme thirst. Her urine output was 500-600 mL/hr. Laboratory studies showed a serum sodium concentration of 156 mEq/L with a plasma osmolality of 320 mOsm/kg. Her urine osmolality ws 65 mOsm/Kg. What type of IV fluids is most appropriate for this patient?
The major deficit is a free-water deficit, so you need to replace wiht electrolyte-free water (as in 5% dextrose in water) until adequate water intake can be achieved by mouth. Giving sodium-containing fluids would only exacerbate the polyuria by superimposing a solute diuresis on the existing water diuresis.
CASE - A healthy 24-year-old woman was involved in an automobile accident, and sustained a fracture of her jaw, multiple facial bone fractures, and a brief loss of consciousness. In the emergency department, and IV infusion of 5% dextrose in 0.45% normal saline at 125 mL/hr was started. Twelve hours after admission to the hospital, she is awake and alert, but has difficulty talking and swallowing because of her injuries, and she complained of extreme thirst. Her urine output was 500-600 mL/hr. Laboratory studies showed a serum sodium concentration of 156 mEq/L with a plasma osmolality of 320 mOsm/kg. Her urine osmolality ws 65 mOsm/Kg.
What other treatment will this patient probably need besides a replace of fluids?
Replace the missing hormone - Desmospressin. There may be recovrey of ADH function as the patietn recovers from the trauma, so a short-acting form should be used and the patient monitored.
CASE - A 37-year-old man with a history of chronic hepatitis C presents to the emergency department with complaints of abdominal swelling, fatigue, easy bruising, yellow eyes, and pruritis. On examination, the patient has abdominal ascites, spider angiomas, and numerous bruises on the skin, icteric sclera, and peripheral edema. Laboratory tests reveal slightly elevated liver function tests, prolonged clotting, hypoalbuminemia, hyperbilirubinemia, elevated ammonia, and hypokalemia. He is diagnosed with cirrhossis of the liver and admitted to the hospital for further workup. What is the normal effect of decreased plasma volume on sodium balance?
Normal effect would be to increase sodium reabsorption.
CASE - A 37-year-old man with a history of chronic hepatitis C presents to the emergency department with complaints of abdominal swelling, fatigue, easy bruising, yellow eyes, and pruritis. On examination, the patient has abdominal ascites, spider angiomas, and numerous bruises on the skin, icteric sclera, and peripheral edema. Laboratory tests reveal slightly elevated liver function tests, prolonged clotting, hypoalbuminemia, hyperbilirubinemia, elevated ammonia, and hypokalemia. He is diagnosed with cirrhossis of the liver and admitted to the hospital for further workup. Why does this patient have significant edema and continued sodium reabsorption?
Low albumin and hypoproteinemia results in a decreaed colloid pressure in blood so fluid escapes to the interstital areas outside of the blood vessels. This is a case of excess retained fluid in conjunction wiht low arterial volume - which increases renin-angiotensin-aldosterone and sodium reabsorption.
CASE - A 37-year-old man with a history of chronic hepatitis C presents to the emergency department with complaints of abdominal swelling, fatigue, easy bruising, yellow eyes, and pruritis. On examination, the patient has abdominal ascites, spider angiomas, and numerous bruises on the skin, icteric sclera, and peripheral edema. Laboratory tests reveal slightly elevated liver function tests, prolonged clotting, hypoalbuminemia, hyperbilirubinemia, elevated ammonia, and hypokalemia. He is diagnosed with cirrhossis of the liver and admitted to the hospital for further workup. In what part of the kidney is the majority of sodium reabsorbed?
proximal tubule
CASE - A 44-year-old woman presents to her gynecologist with complaints of not having had a period for the last 8 months. She reports a negative pregnancy test at home. Upon further questioning, she reports a daily headache, changes in vision, and a milky discharge from the breast. She has no known medical problems and is taking no medications. On examination, she is noted to have galactorrhea and diminished peripheral vsion bilaterally. The remainder of her examination is normal. A pregnancy test is repeated and is negatve. A TSH level is drawn and is normal. Her prolactin level is elevated significantly.
What is most likely?
Secondary amenorrhea with changes in vision, suggest a pituitary tumor producing prolactin.
CASE - A 44-year-old woman presents to her gynecologist with complaints of not having had a period for the last 8 months. She reports a negative pregnancy test at home. Upon further questioning, she reports a daily headache, changes in vision, and a milky discharge from the breast. She has no known medical problems and is taking no medications. On examination, she is noted to have galactorrhea and diminished peripheral vision bilaterally. The remainder of her examination is normal. A pregnancy test is repeated and is negatve. A TSH level is drawn and is normal. Her prolactin level is elevated significantly. How does hyperprolactinemia cause amenorrhea?(2 points)
Elevated prolactin inhibits pulsatile GnRH secretion and There may be a mass effect
CASE - A 44-year-old woman presents to her gynecologist with complaints of not having had a period for the last 8 months. She reports a negative pregnancy test at home. Upon further questioning, she reports a daily headache, changes in vision, and a milky discharge from the breast. She has no known medical problems and is taking no medications. On examination, she is noted to have galactorrhea and diminished peripheral vsion bilaterally. The remainder of her examination is normal. A pregnancy test is repeated and is negatve. A TSH level is drawn and is normal. Her prolactin level is elevated significantly. Why do you check thyroid function in patients with hyperprolactinemia?
Hypothyroidism can result in increased TRH, which can stimulate prolactin secretion.
CASE - A 44-year-old woman presents to her gynecologist with complaints of not having had a period for the last 8 months. She reports a negative pregnancy test at home. Upon further questioning, she reports a daily headache, changes in vision, and a milky discharge from the breast. She has no known medical problems and is taking no medications. On examination, she is noted to have galactorrhea and diminished peripheral vsion bilaterally. The remainder of her examination is normal. A pregnancy test is repeated and is negatve. A TSH level is drawn and is normal. Her prolactin level is elevated significantly. How do you treat this patient?
Dopamine agonist (cabergoline is better tolerated) and surgery if needed, radiotherapy last.
