11.3: {Na] Flashcards
What is blood [Na] equal to?
Total body Na / Total body water
What does water excess w/o change in body Na Cause?
Hyponatremia
How does body respond to increased water intake?
- [Na] drops
- Decrease thirst and ADH release
- Increased renal excretion and decreased thirst normalize
Other names of ADH?
- AVP
- Vasopressin
ADH action?
- Produced by hypothalamus stored in post. pit.
- Acts on distal tubule increase H20 resorption
- Leads to increase urine []
- Causes constriction as well
Definition of concentrated urine?
- Urine osmolality > plasma
- Plasma osmolality usually 300
How is ADH regulated?
- Increased osmolality increased ADH release
- Larger decrease in V. or P. leads to release
- P and V can overcome osmolality
ADH more sensitive to osmolality or P and V?
- Osmolality
% of body weight that is salt water?
60%
What is SIADH?
- Syndrome of Inappropriate ADH
- Increase body water with normal [Na]
- Tumor producing ADH
What is a water pill?
- Diuretic
- Tells body to get rid of salt and water
What can cause hyponatremia?
- SIADH
- Diuretic use with water intake
- Increased TBW and smaller increases in Na
Why is hyponatremia solely from fluid ingestion rare?
Body can create extremely dilute urine by using close to no ADH
What is hyponatremia usually due to?
- Impaired renal water excretion
1. Impaired dilution due to excess ADH
2. Intrarenal factors - Might be ingesting high volume and low solute: beer drinks syndrome, but this is rare
Can body produce pure water?
- No, some Na must be secreted with water
- 50 is lowest body can go
- If you have high water intake and low osmolar intake
- You will pee out all your osmoles
Intrarenal factors leading to hyponatremia?
- Renal failure (decreased GFR)
- Diuretics preventing resorption in distal tubule to create free water
- Solute avidity in prox tubule (CHF) must be able to deliver solute to distal
3 types of hyponatremia? And want it says about TBNa?
- Hypovolemic: decreased TBNa
- Euvolemic: Normal TBNa
- Hypervolemic: Increased TBNa
Signs of hypovolemia?
- Flat neck veins
- Orthostatic Hypotension
- Decreased skin turgor
Causes of Euvolemic hyponatremia?
- SIADH
- Hypothyroidism
- Beer drinkers
- Psychogenic polydypsia
- Normal body Na but too much water
When is edema seen?
Hypervolemic hyponatremia
What causes hypervolemic?
- CHF
- Liver Cirrhosis
- Renal failure
What causes hypovolemic?
- Renal Na loss
- Diuretics
- Diarrhea / vomiting
- Addison’s disease
What does low Urine Na indicate?
- Extrarenal loss of Na
- Or edematous disorder
What does salt avid kidneys mean?
- Like to resorb salt
- Seen in CHF
What does normal urine Na suggest?
- Renal loss of Na
- Or excess ADH
What is hypernatremia?
Increased [Na] with a decrease in TBW relative to Na
Pathogenesis of Hypernatremia?
- In impaired water intake, kidneys can only concentrate urine to a fixed extent of 1200 to minimize water loss
- However there is still insensible water loss that will lead to HYPERnatremia
- This is why we can live without water, if you aren’t peeing it off, you are evaporating it off
3 types of hypernatremia?
- HYPOvolemic: decrease TBNa
- EUVOlemic: decrease TBW, static TBNa
- HYPERvolemic: Increase TBNa
Causes of hypo hypernatremia?
- Renal / extrarenal loss w/ inadequate H2O intake
2. Osmotic Diuresis
Causes of Euvo hyperNa?
- Central diabetes insipidus: trauma / tumor
- Nephrogenic diabetes insipidus: drugs, genetic, HyperCa
- Decreased thirst / water intake
Causes of HYPER hyperNa?
- Hypertonic fluids
- Mineralocorticoid excess
- Salt poisoning / sea water
Treatment of Causes of hypo hypernatremia?
- Hypotonic fluids to repair volume depletion
Treatment Causes of Euvo hyperNa?
- Water administration
2. ADH in central diabetes insipidus
Treatment of HYPER hyperNa?
- Water + ADH to remove excess Na
* **Care to not exceed .5m eq /L/Hr to not shift water into brain leading to brain edema
How to treat acute hyponatremia?
- This is what will be seen in marathon runners
- Inject hypertonic saline
What excludes beer drinkers syndrome or Polydipsia?
Urine osmolality > plasma
How do you treat SIADH?
VAPTANs
Difference between dehydration and volume depletion?
Dehydration: water deficit
Volume depletion: Salt and water deficit
How do you treat hypovolemic hyponatremia?
- Saline
How do you treat hypervolemic hyponatremia?
Diuretics and fluid restriction
How do you treat euvolemic?
Mild asymptomatic: no treatment needed
Severe (
Symptoms of symptomatic euvolemic?
- Confusion
- Seizures
- Coma
