Renal Flashcards
Exam 3
~____% of total body weight is water
60
- varies w/ gender, age, body fat %
- ↑Muscle=↑Water
Intracellular fluid makes up ___ of TBW, while extracellular fluid makes up ___
2/3
1/3
Extracellular fluid includes ______ and ______. What are their respective amounts?
ISF - 3/4
Plasma - 1/4
Osmolar homeostasis is mainly mediated by osmolality-sensors in the?
anterior hypothalamus
Osmolar homeostasis does what 3 things?
- Stimulate thirst
- Cause Pituitary Release of Vasopressin (ADH)
- Cardiac atria releases ANP→act on kidney to ↓Na+/H20 reabsorption
Volume homeostasis is mediated by?
juxtaglomerular apparatus - sense changes in volume
What is the response to dec volume by volume homeostasis?
↓Vol @ JGA triggers Renin-Angiotensinogen-Aldosterone system (RAAS)→Na+/H20 reabsorption
What are the normal values of sodium? What is too low/high for surgery?
135-145 mEq/L
- ≤125 or ≥ 155, want correction prior to elective case
What are the 3 potential underlying causes of hypo/hypernatremia?
- Hypovolemic
- Euvolemic
- Hypervolemic
___% of hospitalized pts are hyponatremia. What are the causes?
15%
- over fluid-resuscitation
- ↑endog vasopressin → inc H2O reabsorption
Hyponatremia d/t hypovolemia causes and differentiation
- Renal losses (urine Na > 20) - diuretic excess, mineralocorticoid deficiency, salt-losing nephritis, renal tubular acidosis, metabolic alkalosis, ketonuria, osmotic diuresis
- Extrarenal losses (urine Na < 20) - vomiting, diarrhea, 3rd space losses, burns, pancreatitis, muscle trauma
Hyponatremia d/t euvolemia causes and differentiation
- Salt-restricted diet (urine Na < 20)
- Other (urine Na > 20) - glucocorticoid deficiency, hypothyroidism, high sympathetic drive, drugs, SIADH
Hyponatremia d/t hypervolemia causes and differentiation
- Avid Na reabsorption (urine Na < 20) - nephrotic syndrome, cardiac failure, cirrhosis
- Renal loses (urine Na > 20) - acute or chronic renal failure
Hyponatremia d/t hypervolemia S/S
peripheral edema, rales, ascites
Neuro S/S of hyponatremia
start with HA and confusion
- N/V, fatigue, muscle cramps
The most severe consequences of hyponatremia include? What is the serum Na level?
Seizures, coma, and death
< 120 mEq/L
What is the tx for hyponatremia?
- Treat underlying cause (look at volume status), electrolyte drinks, NS, diuretics
- Hypertonic/3% NaCl: 80ml/hr over 15h (max 1.5 mEq/L/hr, check Na+ q4h while replacing)
Rapid correction of hyponatremia occurs at what rate and can cause what syndrome?
Rapid correction >6 mEq/L in 24 h)
Osmotic Demyelination Syndrome (often permanent neuro damage)
What is the treatment for hyponatremic seizures?
3-5ml/kg of 3% over 20 min, until seizures resolve
What are the common causes of hypernatremia?
- Excessive evaporation
- Poor oral intake (very young, very old, altered mental status)
- Overcorrection of hyponatremia
- Diabetes insipidus - loss of dilute urine
- GI losses
- Excessive sodium bicarb (treating acidosis)
Hypernatremia d/t hypovolemia causes and differentiation
- Renal salt and water loss (urine Na > 20) - osmotic or loop diuretics, postrenal obstruction, intrinsic renal disease, profound glycosuria
- Extrarenal salt and water loss (urine Na < 20) - diarrhea, GI fistulas, burns, sweating
Hypernatremia d/t hypovolemia s/s
Dec skin turgor, flat neck veins, dry mucous membranes, orthostatic hypotension, tachycardia, oliguria
Hypernatremia d/t euvolemia causes and differentiation
Urine Na variable
- renal water loss: DI (central, nephrogenic, or gestational)
- extrarenal water loss: insensible losses (respiratory tract, skin)
Hypernatremia d/t hypervolemia causes and differentiation
Urine Na > 20 - sodium gains
- hyperaldosteronism, Cushing’s, hypertonic dialysis, IV sodium bicarb, NaCl tablets, hyperalimentation, hypertonic saline enemas, salt water drowning