Flashcards in Sodium Deck (76):
What is the total body water for males?
What is the total body water for females?
What is the ratio of water found in the intracellular fluid?
What is the ratio of water found in the extracellular fluid?
What dictates the ECF volume?
The net gain/loss of Na
Describe the ECF when fluid loss is isotonic?
If fluid/blood loss is isotonic- the osmolality of the fluid is unchanges
-no change in ICF volume
Describe the ECF when fluid loss is hypotonic?
If fluid/blood loss is hypotonic- increases plasma osmolarity
-shifts ICF to ECF
What conditions commonly cause hyponatremia?
-Low total Na
-Hypovolemic patients (dehydrated patients)
-Elevated BUN:Cr ratio
Characteristics of Renal Sodium Loss (2)
- High urinary Na excretion
- High urinary osmolality (concentration)
What commonly causes renal Na loss?
This renal sodium loss is less common and its also called salt wasting nephritis
Renal Tubular Disease
What is typically associated with low urine Na excretion?
Decreased Na intake is commonly seen in patients with...
-Extremely poor diets (anorexia/alcoholics)
-Hospital patients that are on hypotonic IV fluids for a long time
Patients with hyponatremia commonly present with...
-Low Na urine excretion
-High urine osmolality (concentrated)
How do people classify hyponatremia?
What are some factors that you need to know before classifying a patient with hyponatremia?
What is another phrase for hyponatremia with high plasma osmolality
If a patient has elevated ECF osmolality, where does the water shift?
From ICF to ECF
If the fluid shifts from inside the cell to outside the cell, what would this do to the Na concentration?
Dilute the Na concentration
What is the most common cause of hypertonic hyponatremia?
Describe hyperglycemias effect on hyponatremia?
-Osmotic diuresis (increase in urine rate) causes renal Na and water loss
-can further raise plasma osmolality (conc.)
If a patient has hyponatremia due to hyperglycemia, how do you treat?
Treat the hyperglycemia first
-Don't give saline (causes the fluid to leave the ICF)
What is another name for hyponatremia with normal plasma osmolality?
What causes Pseudohyponatremia?
-Hyperproteinemia (multiple myeloma)
What % of plasma is water?
What is the remained 7% of plasma made of?
How does hyperlipidemia and hyperproteinemia cause Pseudohyponatremia?
-The water content of a given volume of plasma is decreased
(the solids have pretty much displaced the water in the plasma)
-Causes plasma sodium to be falsely low
Is treatment required for Pseudohyponatremia?
What is another name for hyponatremia with low plasma osmolality?
Is the volume of the ECF in excess/deficient in hypotonic hyponatremia?
What are a patients urine Na levels if they have renal failure?
Urine Na is greater than 20 meq/L (the kidneys are failing so the volume levels stay high)
What are a patients urine Na levels if they have CHF or hepatic cirrhosis?
Urine Na is less than 20 meq/L (they have increased venous pressure and this results in edema state)
If a patient has edema, where is the edema fluid moving?
From plasma to the interstitial fluid
What does the lose of plasma fluid result in?
Increase in the secretion of ADH and aldosterone
What effect does ADH and aldosterone have?
Causes an increase in the total body water and that exceeds the rise in sodium
What are treatment options for patients with hypotonic hyponatremia with ECF volume excess?
-Judicious sodium (limit sodium to 1-3 grams/day)
-Fluid Restriction (1-1.5 liters/day)
- water intake must be less than urine output
What are some signs of hypotonic hyponatremia with decreased ECF volume?
-Signs of dehydration because total sodium is depleted disproportionally to water losses
What are 2 causes of hypotonic hyponatremia with decreased ECF volume?
-Extra Renal Losses
What are examples of renal losses?
What effect does diuretic therapy have?
Pulls of volume and Na
What effect does adrenal insufficiency have?
-Inability to retain Na and water
What effect do ACE inhibitors have?
-Inability to retain salt and water
What are examples of extra renal losses?
What are clinical signs of hypotonic hyponatremia with hypovolemia?
Usually notice the depletion of water before the hyponatremia
What is treatment for hypotonic hyponatremia with hypovolemia?
-Reexpansion of ECF
-Use isotonic saline and correct any underlying disorders
What causes hypotonic hyponatremia with normal ECF volume?
-Syndrome of inappropriate anti-diuretic hormone
What patients express primary polydipsia?
-Due to excess water intake
Describe urine sodium and urine concentration in primary polydipsia
-Urine sodium is less than 20 meq/L
-Urine osmolality is less than 100 mOsm/kg
What is the treatment for primary polydipsia?
-Monitor plasma Na levels
-Don't want to increase Na too quickly
This is the most common cause of hyponatremia and is the diagnosis of exclusion
Syndrome of inappropriate anti-diuretic hormone
What causes the fluid and electrolyte balance in SIADH?
-Inability to excrete dilute urine
-Water retention in the body
-Low Sodium levels
-Often caused by Small Cell Lung cancer which secretes excess ADH
What are characteristics of SIADH?
-Low Na and osmolarity
-Adequate urine sodium excretion with high urine osmolality
-No evidence of dehydration
What diseases/disorders is SIADH commonly seen in?
What are 2 clinical signs of hyponatremia?
-Observed sodium concentrations are less than 120 meq/L
-Rate of fall in Na is rapid
What are initial symptoms of hyponatremia?
What are progressive symptoms of hyponatremia?
When is treatment of hyponatremia urgent?
-If Na is less than 110 meq/L or the patient is symptomatic
Asymptomatic patients should not exceed over _____ per hour
.5 meq/L per hour
Severe patients should not exceed over ______ per hour
1-1.5 meq/L per hour
Patients should never exceed _____ per day
12 meq/L per day
What is the major cause of hypernatremia?
Lack of free water access
What patients commonly present with hypoernatremia?
-Patients that have neurological problems that don't have thirst signals
The loss of volume leads to _______ BUN:Cr levels?
Elevated (because the kidneys aren't getting perfused and they cant filter)
The loss of volume leads to ______ urine osmolality?
High (because it is more concentrated)
_______ is the best indicator for following volume status
What are the 2 types of Diabetes Insipitus?
Describe ADH in central DI
-ADH is absent
Do your thirst signals remain in central DI?
Yes they do man
What are 2 S and S for central DI?
Central DI is associated with...
What is the treatment for Central DI?
-dDAVP (artificial ADH)
-Stimulates water and Na uptake
How do you confirm Central DI diagnosis?
-If the patient can concentrate the urine after receiving dDAVP
Describe ADH in nephrogenic DI?
-Kidneys are resistant to ADH (so they don't retain Na and water)
What are characteristics/ S&S for nephrogenic DI?
-Patients excrete large volumes of really dilute urine
-Low Na in urine
-Patients still have thirst signals
-If they are unable to get water they will become dehydrated quickly
What people tend to present with nephrogenic DI?
-3rd trimester pregnant patients