Kidney-ADH dx and electrolytes

Question 1

What type of urine and blood osmolality do you see with SIADH?

Answer 1

urine osmolality>blood osmolality

crazy conc’n urine, dilute blood.

Question 2

What is SIADH a common cause of?

Answer 2

hyponatremia

b/c body compensates by decreasing aldosterone secretion

Question 3

What can be the result of the hyponatremia seen in SIADH? How should this be corrected?

Answer 3

cerebral edema and seizures
correct slowly b/c low–>high the pons will die.
Central pontine myelinolysis (demyelination syndrome)–>locked in syndrome.

Question 4

What are some common causes of SIADH?

Answer 4

LUNG AND BRAIN
Ectopic ADH via small cell lung cancer
pulmonary dx
CNS disorders/head trauma
DRugs--cyclophosphamide

Question 5

What is the treatment for SIADH?

Answer 5

fluid restriction
IV hypertonic saline
conivaptan
tovaptan
demeclocycline (ADH antagonist)

Question 6

What are some causes of central diabetes insipidus?

Answer 6

lack of ADH release from hypothalamus
pituitary tumor
autoimmune
trauma
surgery
ischemic encephalopathy
idiopathic

Question 7

What are some causes of nephrogenic diabetes insipidus?

Answer 7

kidney resistant to ADH
hereditary or secondary to hypercalcemia
lithium use
demeclocycline use (ADH antagonist)

Question 8

How do you diagnose central DI v. nephrogenic DI?

Answer 8

see dilute urine and conc’n blood.
do water deprivation test. and still see dilute urine (2-3 hrs)
give vasopressin analog. Works-central. Doesn’t work-nephrogenic

Question 9

What is the treatment for central DI?

Answer 9

desmopressin

Question 10

What is the treatment for nephrogenic DI?

Answer 10

HCTZ (thiazide diuretics cause dehydration and prompt PCT to absorb more water)
Indomethacin (decreases GFR via afferent arteriole constriction)
Amiloride (inhibits the CT sodium channels that take up Lithium and allow it to inhibit ADH receptors).

Question 11

Causes of hyperkalemia?

Answer 11

DO LABS
Digoxin
hyperosmolarity
lysis of cells
acidosis
beta blocker
high blood Sugar (insulin insensitivity)

**also ACE inhibitors, potassium sparing diuretics

Question 12

What can cause hypokalemia?

Answer 12

Insulin (when correcting hyperkalemia give w/ IV dextrose)
beta agonist (albuterol)
alkalosis (bicarb)
cell creation

thiazide and loop diuretics

Question 13

What happens when sodium gets too low or too high?

Answer 13

CNS effects stupor, coma. Seizures w/ hyponatremia.

Question 14

What are 6 causes of hypernatremia?

Answer 14

6Ds
diuretics
dehydration
Diabetes Insipidus
docs (iatrogenic)
diarrhea
dx of kidney

Question 15

What do you see with hypokalemia?

Answer 15

flattened t waves
u waves
muscle spasm
arrhythmias: increased QT interval, torsades de point

Question 16

What do you see with hyperkalemia?

Answer 16

tented (peaked) t waves. Arrhythmias, Wide QRS like vtach.

muscle weakness

Question 17

When potassium is low, what might else be low?

Answer 17

magnesium!

Question 18

Symptoms of low Ca++?

Answer 18

tetany: check Trosseau and Chvostek
seizures
QT prolongation

Question 19

Symptoms of high Ca++?

Answer 19

Stones (renal)
Bones (pain)
Groans (abdominal pain)
Thrones (increase in urinary frequency)
psychiatric overtones (delirium, altered mental status)

Question 20

Low Magnesium causes what?

Answer 20

tetany
torsades de point
hypokalemia

Question 21

High magnesium causes what? When might you see this ?

Answer 21

decreased deep tendon reflexes
lethargy
bradycardia
hypotension
cardiac arrest
hypocalcemia
**Mg given to moms in premature labor to stop contractions. Go too high see diminished reflexes.