Fluid And Electrolyte Disturbances Flashcards
Dopamine
Natriuretic effect
Aldosterone
Activates Na Cl reabsorption within aldosterone-sensitive distal nephron
Mannitol
Filtered by glomeruli
Not reabsorbed in proximal tubule
Causes osmotic diuresis
Acetazolamide
Inhibit proximal tubular Na Cl absorption via inhibition of carbonic anhydrase
Trimethoprim and pentamidine
Inhibit distal tubular Na reabsorption through amiloride sensitive ENaC channel
Daily fecal fluid loss
100-200 ml/day
Insensible losses
500-650 ml/day
Hypovolemia and
Hypochlormeic alkalosis due to vomitting diarrhea or diuretics
What is the expected urine na?
> 20
Renal causes of hyponat
Expected Urine Na?
> 20
Inhibits renal concentrating activity, thiazides or loop diuretics?
Loop (blunts countercurrent mechanism)
Cerebral salt wasting
Hypovolemic hyponat
UNa > 20 (inappropriate natriuresis)
Assoc w: SAH TBI Craniotomy Encephalitis Meningitis
Hypervolemic hyponat with Urine Na > 20
Acute or chronic renal failure
Primary vs secondary AI in terms of volume status and Na levels?
Primary- hypovolemic hyponat
Secondary- euvolemic hyponat
Most common cause of euvolemic hyponat?
SIADH
Other causes euvolemic hyponat?
Glucocorticoid deficiency Hypothyroidism Stress Drugs SIADH
Class of drugs which most commonly cause SIADH
SSRIs
Most common malignancy assoc w SIADH
Small cell lung Ca
Symptomatic hyponat at levels..
<125
Overly rapid Na correction
> 8-10 in 24 hrs
> 18 in 48 hrs
ODS presentation
Paraparesis / quadriparesis Dysphagia Dysarthria Diplopia Locked in syndrome LOC
AVP agonist
Desmopressin
Most common manifestation of hypernatremia
Altered mental status
Correction of acute hypernat
Rate of 1mM/hr
Nephrogenic vs central DI in response to DDAVP
Nephrogenic - less than 50% increase in Urine osmolality pr <150 mOsm/kg from baseline
Nephrogenic DI causes
Genetic mutations
Hypercalcemia
Hypokalemia
Drugs (lithiumn ifosfamide, antiviral agents)
Major K channels that mediate its secretion
ROMK - mediate bulk of K secretion
Flow sensitive big Potassium (BK) channel
Increase in distal delivery of Na and distal flow rate: effect on K?
Enhance K secretion —> hypokalemia
Decrease distal delivery of Na, effect on K?
Blunts ability to excrete K —> hyperkalemia
Aldosterone effects on K
Increases activity of ENaC—> K secretion —> hypoK
Possible treatment for TTP
Propanolol 3mg/kg
Urine calcium in hiazide diuretics vs loop diuretics
HYPERcalciuria in LOOP diuretics
HYPOcalciuria in THIAZIDE diuretics
Liddle syndrome
Autosomal dominant Gain in function mutation in ENaC Severe hypertension + hypokalemia Unresponsive to spironolactone Sensitive to amiloride
Hypokalemic alkalosis
Loss of function of TALH
Bartter’s
Hypokalemic alkalosis Loss of function of DCT segments Chondro calcinosis (abnormal deposition of CPPD in joints) Hypomagnesemia Marked hypocalciuria
Gittleman’s syndrome
ECG changes with K <2.7 mmol/L
Broad flat T waves
ST depression
QT prolongation
Same clinical manif with Liddle’s syndrome but
Responds to spironolactone
SAME (syndrome of apparent mineralocorticoid excess)
Reduction of serum K by 2.0 mM results in loss of ____ mmol of total K stores
400-800 mmol
ECG changes in hyperkalemia
Tall peaked T waves - 5.5-6.5
Loss of p waves 6.5-7.5
Widened qrs 7.0-8.0
Sine wave pattern > 8.0
Effect of hypercalcemia in px taking digoxin
Potentiates cardiac toxicity of digoxin
Effect of Calcium gluc
Effect starts in 1-3 mins,
Lasts 30-60 mins
May repeat if no ECGchanges (hyperkalemia)
Glucose insulin solution
Effect begins 10-20 mins
Peaks 30-60 mins
Lasts 4-6 hrs
If cbg > 200-250 , hold D5W
Beta blockers for hyperkalemia
Albuterol 10-20 mg Inhaled over 10 mins Effect starts at 30 mins Peak at 90 mins Lasts for 2-6 hrs
