Disorders of Na and Water- Heemer

What is the normal Serum Osmolality in the body?

What is the normal Serum Osmolality in the body?

275-290 mOsm/kg

Def of hypovolemia

loss of Na and water exceeding intake

Signs/Symptoms of Hypovolemia

• lower plasma vol

• hypotension, tachycardia

• thirsty, fatigue, weak, cramps, dizzy

• diminished skin turgor

• altered mental status

Causes of hypovolemia (low volume):

Think: anything that would cause us to lose fluid

Outside the renal system:

• GI Issues

  • vomiting, diarrhea, ng suctioning

• Skin/respiratory

  • sweat, burns

• Hemorrhage (blood loss)

Renal System:

• diuretics

• hypoaldosteronism

• osmotic diuresis, salt wasting nephropathies

Would you expect a person with hypovolemia to have high or low BUN/SCr ratio?

HIGH (normal is 10:1, in hypovol it’s 20:1 or higher)

How is mild and severe hypovolemia treated?

mild- fluids like gatorade/pedialyte

severe- IV NS!!!!!!!!!!!!!!!!!!!!!!!!!!!

How does edema develop?

• can’t excrete sodium

• decrease in BV even though normal ECF

• Increased cap/venous pressure

• altering starling forces

What medication can be used to treat edema?

diuretics

What is the treatment for life-threatening pulmonary edema?

IV Diuretics

In order to treat edema, we also need to treat the _____________ _______________ and restrict ________ in the diet.

In order to treat edema, we also need to treat the underlying cause and restrict Na in the diet.

Generic names of the 4 loop diuretics:

1. Furosemide

2. Bumetanide

3. Torsemide

4. Ethacrynic Acid

What is the most potent diuretic?

Loop

MOA of Loop diuretics:

inhibit NKCC transporter in loop of henle

Contraindications of loop diuretics:

• sulfonamide allergy (except ethacrynic)

• anuria (can’t pee)

• liver coma

• low electrolytes

ADRs of Loop Diuretics:

• low Na, K, Cl, Ca

• Hyperuricemia, Hyperglycemia

• Ototoxicity

How do we overcome diuretic resistance?

• combine diuretics (loop+thiazide)

• increase dose

Name 3 thiazide and 3 thiazide-like diuretics:

Thiazide:

• Chlorothiazide

• Hydrochlorothiazide

• Methyclothiazide

Thiazide-Like:

• Chlorthalidone

• Indapamide

• Metolazone

MOA of Thiazide Diuretics:

inhibit Na/Cl symporter in distal tubule

Contraindications of Thiazide Diuretics:

• sulfonamide allergy

• anuria

• pregnant

ADRs of Thiazide Diuretics:

• low Na, K, Cl

• increased Ca

  • (different than loop)

• Hyperuricemia, hyperglycemia

Hyponatremia Risk Factors:

• age

• nursing home pts

• exercise induced

  • marathon runners

Below _____ mEq/L is considered hyponatremia.

135

Acute Symptomatic Hyponatremia results from an _____________ in neuron volume and cerebral ___________.

results from an increase in neuron volume and cerebral edema.

Symptoms of mild, moderate, and severe acute symptomatic hyponatremia:

(idk how important this is to know)

mild- HA, nausea

moderate- HA, lethargy, disoriented

severe- coma, seizure, respiratory arrest

treatment of acute symptomatic hyponatremia:

NS or 3% saline (be careful)

Improper therapy/ Rapid correction of the hypotonic state of the brain can cause:

osmotic demyelination

Can I use NS to correct low osmolarity/hypotonic state in the brain?

YES

Can I use 3% saline to correct low osmolarity/hypotonic state in the brain?

NO- OSMOTIC DEMYLENIATION

DO NOT raise serum Na more than ____ mEq/L wihtin 24 hours.

12

To determine whether or not you have isotonic, hypotonic, or hypertonic hyponatremia, you must calculate what?

DON’T HAVE TO MEMORIZE THE EQUATION JUST BE ABLE TO RECOGNIZE!!!!!!!!!!!!

serum osmolarity

Isotonic Hyponatremia is called _______________. It’s uncommon, but usually caused by what?

• called pseudohyponatremia

• caused by:

  • hyperlipidemia, hyperproteinemia

  • (treat what’s causing this)

Hypertonic Hyponatremia causes:

Think: something is causing water to be pulled out of the cells= causes low Na conc

Causes:

• hyperglycemia

• osmotic diuretics

For hypotonic hyponatremia what is the 1st thing to determine?

fluid status (hypovolemic, hypervolemic, euvolemic)

Causes of hypovolemic hypotonic hyponatremia:

• transient hypernatremia

  • marathon runners

  • think: we running lots and losing fluids, so we release lots of ADH, but then we done running and drink tons of water= causes hyponatremia

• causes outside renal system:

  • diarrhea, sweating

• renal system causes

  • diuretics

  • adrenal insufficiency

hypovolemic hypotonic hyponatremia treatments:

• NS

• when volume restored= switch to 0.45% NS

MOST COMMON CAUSE OF euvolemic hypotonic hyponatremia:

SIADH

Causes of SIADH:

• tumors

• CNS disorders

• pulmonary disorders

• drugs

Other causes of Euvolemic Hypotonic Hyponatremia:

• renal/adrenal insufficiency

• hypothyroidism

• polydipsia

• low sodium diet

What happens to water and Na in the following conditions:

• euvolemic hypotonic hyponatremia

• hypovolemic hypotonic hyponatremia

• hypervolemic hypotonic hyponatremia

• euvolemic hypotonic hyponatremia

  • normal Na

  • high water

• hypovolemic hypotonic hyponatremia

  • low Na

  • low water

• hypervolemic hypotonic hyponatremia

  • high Na

  • high water

SIADH treatment

• restrict water

• treat underlying cause

• increase solute uptake

• Meds: Demeclocycline, Vaptans

What % NaCl is usually used in patients with Euvolemic Hypotonic Hyponatremia?

3% NaCl

Demeclocycline inhibits the action of

ADH

Causes of Hypervolemic Hypotonic Hyponatremia:

• CHF

• cirrhosis

• nephrotic syndrome

What should be restricted for a patient with Hypervolemic Hypotonic Hyponatremia?

• salt and water

Treatment for Hypervolemic Hypotonic Hyponatremia caused by CHF:

• digoxin

• ACE Inhibitors

• ARBs

Treatment of symptomatic patients for Hypervolemic Hypotonic Hyponatremia:

• 3% NaCl

• fluid restriction

• loop diuretics

What are the names of the 2 ADH antagonists approved for treatment of euvolemic or hypervolemic hyponatremia pts?

1. Conivaptan

2. Tolvaptan

Conivaptan:

• MOA

• ROA

MOA- antagonizes ADH receptors

ROA- IV

Conivaptan:

• CIs

• Cautions

• ADRs

CI:

• hypovolemic hyponatremia (pretty obvious)

• hypersensitivity

• using a CYP 34A inhibitors

Cautions:

• anything that’s gonna deal w/ low volumes (hypotension, hypovolemia, etc.)

• heart failure, renal/liver impairment

ADRs:

• hypotension, fever, low K

Tolvaptan:

• MOA

• ROA

MOA- antagonizes ADH receptors

ROA- oral

Tolvaptan:

• CIs

• Cautions

• ADRs

CI

• NOT for pts. that need IMMEDIATE TREATMENT

• hypovolemic hyponatremia

• hypersensitivity

• anuria

Cautions

• don’t use w/ 3% NaCl

• monitor Na, K, and vol status

• use of CYP 3A inhibitors/inducers

• cirrhosis patients

ADRs

• common: thirsty, constipated, hyperglycemia, anorexia, polyuria

• serious: DVT, V-fib, DIC, CVA, PE, rhabdomyolysis

FDA warning and boxed warning for Tolvaptan

FDA Warning:

• can cause liver damage

• not used longer than 30 days

Boxed:

• only start/resume therapy in hospital where Na levels can be closely monitored

Drug Interactions of Tolvaptan:

• CYP 3A inhibitors/inducers

• P-gp inducers

• digoxin

Great Summary Slide:

Rapid correction of a hypertonic state/high osmolarity of the brain can cause:

cerebral edema

Hypernatremia is caused by a ____________ in neuronal cell volume.

decrease

Treatment of hypovolemic hypernatremia:

• 0.9% NS

• once volume restored—>0.45%NS, or D5W

Treatment of Hypervolemic/Euvolemic Hypernatremia:

• hyperglycemia induced diuresis

• postobstructive diuresis

• hyperglycemia induced diuresis

  • insulin

  • 0.9% NS

• postobstructive diuresis

  • infuse hypotonic fluids

    • 0.45% NaCl

What happens to ADH in a patient with Diabetes Insipidus?

• low ADH output or

• decreased response to ADH

Central Diabetes Insipidus treatment:

Desmopressin

• PO or Nasal

• NASAL recommended

Nephrogenic Diabetes Insipidus treatment:

• stop drugs that contribute to the condition

• correct high calcium and low potassium

• restrict sodium

• thiazide diuretic

• indomethacin

Treatment of sodium overload:

• loop diuretics

  • increase sodium excretion

• IV D5W