renal-exam 1-sodium homeostasis

135-145 mEq/L, >90% of the osmolality of the ECF

serum osmolality >285, excessive nonsodium effective osmoles, excess glucose, treatment: treat underlying cause

serum osmolality 280-285, more of a lab artifact and pretty much a non-issue today because of improved laboratory methods of measuring serum sodium

serum osmolality <280, can be hyper, iso and hypovolemic

P osm=2 * (Na) + glu/18 + BUN/2.8

serum sodium <135 mEq/L

n&V, anorexia, lethargy, HA, muscle cramps

restlessness, disorie, agitation, psychosis, depressed deep tendon reflexes (DTR), Cheyne-stokes respiration, seizures, coma, respiratory depresion, permanent brain damage, death

measured serum osmolality-calculated osmolality>15 indicates presence of excess hyperosmolar compounds-may be due to hyperglycemia, for every 100 mg/dl increase in blood sugar>normal, serum sodum decreases 1.7 mEq/L, admin of hyperosmolar solution (mannitol, glycerin), toxicity/poisoning (ethanol, methanol, ethylene glycol)

posm<280, loss of sodium and water but sodium >>water loss

postural hypotension, HR > or equal 100bpm, SBP <100 mmHg

>20mEq/L(most common cause) thiazide diuretics(decreased sodium reabsorption), sodium losing renal diseases (nephritis, salt wasting nephropathy), addison's disease (lack of aldosterone)

1. hemodynamically unstable 2. CNS symptoms present 3. rate of sodium replacement

restore intravascular volume 1st (NS or LR 200-300mL/hr, faster if need more volume

restore ECF volume deficit=ECF norm-ECF current(use ABW even if >130%), kg * 0.2, give NS or LR at 100-150 mL/hr for L needed

restore sodium deficit, endpoint 120-125 mEq/L or until symptoms abadate, use CBW or ABW

<48 hours, NaCl infusion or 3%, calculate change in serum sodium=mEq Na/L in replacement IV-serum Na/(TBW +1), 1. replace with 0.9 plus or minus loop diuretic 2. replace with 3%(potential for error is higher), (513mEq/L plus or minus loop, MUST use infusion pump to deliver no faster than 1-2 mL/kg/hr inititially for first 1-3 hours(100-150mL/hr) 3. check serum sodium q 2-4 hours titrate infusion to raise serum sodium no faster than 2 mEq/L/hr

>48 hours, 1. estimate volume of NaCl infusion req to restore sodium deficit using normal saline,2. replace 1/2 over 1st 24 hours and remainder over next 24-72 hours 3. check serum sodium q 4-6 hours initially, titrate infu to raise serum sodium no faster than 0.5mEq/L/hr

no more than 8-12 mEq/L/day

normal total body sodium and a small increase in total body water, ALWAYS an imbalance of water intake and excretion due to 1.altered thirst 2. inappropriate ADH secretion, 3. defective renal diluting mechanisms

severe hypothyroidism, GC deficiency, psychogenic water drinking(>20L/d), SIADH

Uosm>>100mOsm, UNa>>20 mEq/L(very concentrated urine)

cancer(secrete ADH), CNS disorders or insults, pulmonary, major surgery, pain, decreased solute intake

nicotine, opiates, cyclophosphamide, vinc/vinblastine, phenothiazines, tricyclics, MAOI, carbamazepine, NSAIDs, desmopressin, oxytocin, ecstacy, SSRIs

fluid restrict to 1-1.5 L/d plus or minus furosemide (20 mg q 4-6 hours) 1. correct with 3%(need to use), endpoint 120-125mEq/L, must use infusion pump to deliver NFT 1-2cc/kg/hr initially, monitor Na, VS, sx, and fluid status q 2-4 hours in first 24 hou, titrate to raise NFT 1-2 mEq/L/hr in first 24 hours and then decrease over remaining 24 hours

AVP receptor antagonsits (aquaretics)-contra in hypovolemia, conivaptan or tolvaptan

fluid restrict 1-1.5 L/day plus or minus demeclocycline 300 mg qid-blocks effects of ADH in collecting ducts, onset 3-6 days(long) or plus or minus increase solute ingestion and increase free water excretion by increasing salt intake (2-3 gm over usual + lasix) or urea 30gm/d

increased total body water and sodium but water>>sodium

CHF, syndromes assoc with decreased plasma alb (cirrhosis, nephritic syndrome, malnutrition), chronic renal failure(renin-angio system), pregnancy(increased blood volume)

correct underlying cause, fluid restrict, saline restrict(<2.4g/d), loop diuretics (increase free H20 excretion)

>145 mEq/L, always hypertonic-reflects a water deficit relative to sodium, classify according to volume status

thirst, fever, NV, Gi cramping, lethargy

only if acute increase in serum sodium, altered mental status, irritability, restless, muscle spasm, hyperreflexia, spaticity, seizures, coma, death

slow correction is mandatory as rapid lowering may result in cerebral edema, seizures, permanent neurological sequelae and death can occur

TBW loss

diuretics, glycosuria, acute/chronic renal failure

adrenal, GI losses, repiratory losses, skin losses

1. hemodynamically unstable, yes replace intravascular (200-300mL/hr with NS or LR, if not 2. replace TBW deficit

TBW deficit(L)=Current TBW x [(na/140)-1], use CBW or ABW, replace with , use D5W(0 mEq/L) or 0.45(77mEq/L), or oral water, double check with change in serum sodium=mEq Na/L in replacement IV-serum Na conc/TBW +1

1/2 over first 24 hours, remainder over next 24-72 hours, monitor Na, fluid status, sx q 2-4 hours x 1st 24 hours

<24 hours-serum sodium should decrease NFT 1mEq/L/hr

>24 hours, serum sodium should decrease NFT 0.5 mEq/L/hr

Na<145 mEq/L, replace ongoing water loss

clinically euvolemic, total body sodium normal; small volume of pure water loss

central diabetes insipidus(insufficient amt of ADH),nephrogenic diabetes insipidus(kidneys don't respond to ADH), drugs(demeclocycline, lithium, phenytoin, clozapine), high insensible loss(skin and respiratory), Iatrogenic(insufficeient fluid intake)

calc water deficit and correct with free water, treat underlying cause

desmopressin (DDAVP), aqueous vasopression (ADH), chlorpropamide(increase kidney's response to ADH), clofibrate(increase ADH release), carbamazepine(increase response to ADH), HCTZ(increase sodium excretion), indomethacin(inhibits PG in kidneys(increase ADH effect)

increased total body sodium>>increased total body water

iatrogenic, MC excess(primary aldosteronism, cushing's syndrome, congenital adrenal hyperplasia, admin of GC or MCs)

d/c offending hypertonic agent, diuretics(loops and thiazides), hemodialysis(with acute renal failure)