Na+ Disorders (lec 2) Flashcards
ECF Cationº?
Anionº?
Na+
Cl-
ICF Cationº?
Anionº?
K+
PO4-
TBW composition?
2/3 ICF
1/3 ECF: 3/4 ISF, 1/4 plasma
Osmolality is?
[solute] of a fluid
What osmotically active substances are used to calculate osmolality?
Na+
Glu
BUN (blood urea nitrogen)
Isotonic (proportional H2O/solute) Δ in ECF Fluid results in?
size of ECF compartment Δs but no fluid moves b/w ECF/ICF
*Δ confined to ECF
Isotonic ↓ in ECF results in?
e.g. dehydration
↓ size of ECF compartment
no fluid movement
Isotonic ↑ in ECF results in?
e.g. IV
↑ size of ECF compartment
no fluid movement
Hyponatrimic Δ (Na+ deficit) in ECF results in?
movement of fluid from ECF into ICF compartment,
cell swells
*Δ effects ICF
Hypernatremic Δ (Na+ excess) in ECF results in?
movmt of fluid from ICF into ECF compartment,
cell shrinks
*Δ effects ICF
Possible Volume status of pt? (3)
Euvolemic (normal)
Hypervolemic (overload)
Hypovolemic (dehydration)
Hypovolemia presentation?
↑ thirst ↓ sweat ↓ urine output, ↑ concentration Dry skin CNS depression Weak, mm cramps Ortho hypoTN Ortho ↑ pulse
Anasarca is?
total body edema
Hypervolemia presentation?
Edema SOB Orthopnea/nocturnal HTN Tachycardia JVD Crackles
Hypovol caused by?
fluid loss
fluid sequestration
GI bleed
Hypervol caused by?
renal Na+ retention
heart, liver, renal dx
Intravascular Volume is?
fluid volume in bv
effective circulating vol
Intravascular Vol important why?
homeostasis mechanisms respond to intravasc vol, not total extracellular vol
\\\ dx w/ low intravas vol but high extracell vol keep stim salt/H2O retention
(HF, liver F)
Body responds to hypovol how?
Thirst
ADH (anti-di hormone)
Body responds to a change in osmolarity that causes hypovolemia how?
CNS stim:
ADH release -> H2O retention
Angio II stim -> thirst
Body responds to↓ circulating H2O vol how?
Baro stim:
ADH release -> H2O retention
Angio II stim -> thirst
Body responds to Need for Salt Retention how?
Renin-Angio system
Renin-Angio System
increases circulating blood vol how? (slide 28)
↓ in circulating blood vol -> ↓ renal perfusion -> stims juxtaglomerular cells -> renin released -> angiotensinogen to angio I (vasoconstrictor) -> convert to angio II -> aldosterone released -> ↑ Na+ retention -> ↑ circ blood vol
Release of Aldosterone affects Na+ how?
K+ how?
↑ Na+ retention
↑ K+ excretion
Almost all Na+ located where in body?
ECF
Hypernatremia results from what level of Na+?
> 145
HyperNa+ caused by? (3)
low diet H2O
high diet salt
large H2O loss
(Too little H2O relative to Na+)
HyperNa+ signs/sxs due to?
brain shrinkage
HyperNa+ signs/sxs ?
thrist (1st sign) altered mental state weakness neuromm irritability focal neuro defects seizure, coma
Methods of water loss that result in hyperNa+?
GI: Diarrhea
Skin: Excess sweating, burn
Renal: hyperglycemia in DM (obligate ↑ urine output to manage ↑ glucose)
Drugs: diuretics, lithium
Hypovolemia need for ↑ blood volume affects osmotic needs how?
Need for ↑ blood volume overrides osmotic needs of body
Normal response to hyperNa+?
Thrist
concentrate urine to ↓ more H2O loss
Homeostatic Order of importance in body?
Volume, pH, electrolytes
Diabetes Insipidus is?
Caused by?
collecting ducts impermeable to H2O
Central: impaired ADH secretion
Nephrogenic: kidney doesn’t respond to ADH
D Insipidus results in?
dilute urine even though serum Na+ is high
should be concentrated
Nephrogenic D Insipidus etiology?
Tx?
genetic or acquired (result of dxs)
Thiazide diuretics
Amiloride (K+ sparing diuretic)
HyperNa+ tx?
hospitalize severe
stop H2O loss
replace H2O*
*slowly if been several days or will cause rapid swelling of brain
HypoNa+ results from what level of Na+?
< 135
Danger zone < 125
HypoNa+ sxs?
weak, lethargic
N/V
mm cramps, seizure, coma
HypoNa+ is most common what?
electrolyte abnormality in hospitalized pts
Pseudohyponatremia is?
Hyper- glu, protein, lipids cause water movement from ICF into ECF
ECS Solutes are diluted so Na+ registers as low but total body Na+ is actually not low
(HypoNa+ from hyperosmolar state)
HypoNa+/Hypervol caused by?
fluid overload from:
CHF
renal dx
cirrhosis
HypoNa+/Hypervol signs?
edema
JVD
(P) dilutional anemia
HypoNa+/Euvol caused by?
Hyperthyroidism
SIADH
Diuretics
Adrenal insufficiency
SIADH (synd of inappr ADH secretion) due to?
impaired renal free water excretion (due to high ADH release)
*most common cause of HypoNa+/Euvol
SIADH caused by?
neuropsych dx
malignancy
pulmonary dx
drugs (TCA, carbamazepine, anti-neoplastic, narcotics)
SIADH characteristics? (3)
low serum osmolarity,
high concentrated urine,
high ADH (vasopressin) levels,
normal renal, adrenal, thyroid fxn
HypoNa+/Hypovol caused by?
Renal: diuretics, osmotic diuresis, addisons
Nonrenal: V, diarr, pancreatitis, peritonitis
HypoNa+/Hypovol characteristics?
dehydration:
dry mmemb, poor turgor
ortho BP/pulse Δs
HypoNa+ tx?
Hospitalize
Tx cause
vasopressin (ADH) anatgonists
Hyper- or euvolemic: restrict fluids
Hypovol: replace fluids w/ isotonic saline
Chronic HypoNa+ tx?
Demeclocycline to induce Nephrogenic DM Insipidus