Sodium disorder exam 2

normal Na values

135-145 mEq/L

vasopressin key in _________

water balance

hyponatremia values

mild: 125-130

moderate: 115-125

severe: <115

serum osmolality equation

2Na + glucose/18 + BUN/2.8

hypERtonic hypOnatremia osmolality

lab serum osmolality: high

equation: high or low

>290 mOsm/kg

hypERTONIC hypOnatremia causes

hyperglycemia

mannitol: draws water out

hyperglycemia Na correction

corrected/actual Na = measured Na + 1.6[(glucose - 100)/100]

hypOTONIC hypOnatremia

Na loss and water retention compensation for volume loss

working kidney releases free water to try and keep Na conc high

step 1: find volume status

step 2: renal function

hypOVOLemic hypOnatremia renal loss

uNa > 20 mEq/L

causes:

main: thiazides: waste Na more than water

mineralocorticoid deficiency

salt-wasting nephropathy

hypOVOLemic hypOnatremia extrarenal loss

uNa < 20 mEq/L

causes:

vomiting

diarrhea/fistula

pancreatitis

bowel obstruction

burns/open wounds

excessive sweating

EUVOLemic hypOnatremia

uNa < 20 mEq/L

uOsm < 100 mOsm/L

causes

main: low solute intake

primary polydipsia: peeing too much dilute pee

EUVOLemic hypOnatremia

uNa > 20 mEq/L

uOsm > 100 mOsm/L

causes

main: SIADH: water intake more than kidney activity

hypothyroid

glucocorticoid deficiency

hypERVOLemia hypOnatremia

uNa > 20 mEq/L

causes

acute kidney injury

chronic kidney disease

hypERVOLemia hypOnatremia

uNa < 20 mEq/L

causes

cirrhosis

nephrotic syndrome

HF

fluid overload

treatment hypOVOLemia hypOnatremia asymptomatic

treat underlying cause

maintenance fluids

replace ongoing losses

additional isotonic fluids for rehydration (often is bc of severe dehydration

treatment hypOVOLemia hypOnatremia symptomatic

isotonic fliud bolus (NS preferred over LR)

NOT treatment hypOVOLemia hypOnatremia symptomatic

3% hypertonic saline

arginine vasopressin receptor antagonist (VRA): gets rid of too much water

treatment hypERVOLemic hyponatremia

fluid restriction: lower maintenance fluid -> treats hyponatremia

loop diuretics & Na restriction: gets rid of water -> treats water overload

treat underlying disorder

NOT treatment hypERVOLemic hyponatremia

no Na treatment -> more Na holds onto more water; could lead to seizure

thiazide diuretics: more Na loss than water loss -> worsen hyponatremia

SIADH non-med etiologies

infections: meningitis, respiratory

post-op surgery: stress, low Na fluids

stressful states: hypotension, pain, brain trauma, stress

cancer

SIADH med etiologies inc ADH release

amitriptyline

nortriptyline

haloperidol

SIADH med etiologies inc sensitivity ADH

can happen even after discontinuation of therapy

most common: carbamazepine, oxcarbazepine

desmopressin: bed wetting, vasopressin

SIADH med etiologies mixed/uncertain mech

most common: citalopram, sertraline

cyclophosphamide

treatment SIADH

stop offending agent/choice alternative

fluid restriction: 50-75% of maintenance

2nd line: vasopressin antagonist

EUVOLemic hypOnatremia leads to

inc TBW

hyponatremic encephalopathy

so little Na cells cant function and will never function again

permanent neurologic impairment

treat symptomatic or serum Na <115 mEq/L EUVOLemic hypOnatremia

sodium replacement

(for seizure)

principles to treat hypOnatremia

determine chronic vs acute

determine severity

symptomatic vs asymptomatic

hypOnatremia Na replacement goal

safe Na: 120-130

do NOT inc Na > 1-2 mEq/L/hr

0.5 mEq/L/hr inc if chronic

no more than 12 mEq/L/24 hrs

rapid inc or dec in Na causes

central pontine myelinolysis: irreversible neurologic injury

calc Na deficit

(8 to 10) x TBW

divide answer by body weight to find rate

hypertonic saline 3%

good for seizures 513 mEq/L

peds: 4mL/kg -> inc Na by 1mEq/L

men: 100mL -> inc Na by 1.5

women: 100mL -> inc Na by 2

ONLY CENTRAL LINE

conivaptan/Vaprisol IV

vasopressin antagonist

competitively binds to V2 -> inhibits ADH-dependent water reabsorption

2nd line acute

EUVOlemic and hypERVOLemic hypONa

avoid with CYP3A4 inhibitors and p-glycoprotein

adverse effects: dry mouth, hepatotoxicty, hypERnatremia, DI, hypotension, hypERnatremia

tolvaptan/Jynarque, Samsca PO

vasopressin antagonist

competitively binds to V2 -> inhibits ADH-dependent water reabsorption

chronic management

chronic EUVOLemia, hypERVOLemia

avoid with CYP3A4 inhibitors and p-glycoprotein

adverse effects: dry mouth, thirst, hepatotoxicity, hypERnatremia

demeclocycline

non-selective AVP receptor antagonist

tetracycline-like antibiotic

2nd line

chronic treatment of SIADH when fluid restriction does work

300mg bid-qid

adverse events: liver disease, renal dysfunction

contraindicated: < 8 years old -> stains teeth

chronic hypOnatremia causes

low solute intake

neonatal diuretic use

chronic SIADH after fluid restriction/vasopressin antagonists

chronic hypOnatremia treatment adults

replace with enteral Na

NaCl, Na citrate

1g NaCl = 17.1 mEq

pinch = 6.5 mEq

chronic hypOnatremia treatment peds

1-2 mEq/kg/day in divided doses

hypERnatremia causes

mild-moderate: 145-160

severe: >160

excessive Na

water deficit

combo of water and Na deficit

hypERnatremia mech of defense

concentrate urine

thirst

inc ADH

hypERnatremia signs and symptoms

hyperosmolar symptoms: water moves from ICF to ECF

brain cell shrinkage, hemorrhages, cerebral contraction

thirst, dry mucus membranes

mild-moderate: lethargy, weakness, confusion, irritability

severe: twitching, seizures, coma

hypOVOLemic hypERnatremia causes

loss of water >> Na

signs of fluid depletion

dehydration

loop diuretics

severe diarrhea in peds

hypOVOLemic hypERnatremia

treat hypovolemia first

hemodynamically unstable: LR isotonic to inc ECF space

hemodynamically stable: asymptomatic -> free water replacement D5W, D5W 1/4 NS

calc free water deficit

serum Na < 160: usual TBW x [(serum Na/140) - 1]

serum Na > 160: usual TBW x [(serum Na/145) - 1]

replace over 2-3 days

correct free water too fast leads to

osmotic pontine demyelination syndrome

hypERVOLemic hypERnatremia causes

hypertonic saline

Na bicarb solutions

mineralocorticoid excess

hyperaldosteronism

hypERVOLemic hypERnatremia treatment

eliminate Na sources

thiazide diuretic

free water replacement with loop

EUVOLemic hypERnatremia causes

dec TBW

central diabetes insipidus

nephrogenic diabetes insipidus

dec ADH secretion/response

inc urine output

central DI causes

dec ADH secretion

idiopathic

CNS: brain trauma meningitis

familial causes

nephrogenic DI causes

kidneys do not respond to ADH

electrolyte changes: hypercalcemia, hypokalemia

familial causes

meds: LITHIUM, cidofovir, amphotericin B, demeclocycline, foscarnet, conivaptan, tolvaptan

DI treatment

1st line: symptomatic: correct free water deficit; head injury -> vasopressin at low dose to hit V2

central DI treatment 2nd line

A) DDVAP

B) carbamazepine

C) indomethacin

nephrogenic DI treatment 2nd line

A) hydrochlorothiazide

B) DDVAP

C) indomethacin, amiloride: lithium

DI monitoring

Na correction: < 12 mEq/L/day (0.5 mEq/L/hr)

urine output