Fluids, Electrolytes, Acid-Base Disorders, and Nutrition Support
ECF volume
status
Hypervolemic
Euvolemic
Hypovolemic
Physiologic
Findings
Edema, large positive
fluid balance, pulmonary
infiltrates without pneu-
monia, enlarged heart,
increased PCWP, EDVI
No evidence of fluid overload or
dehydration, fluid equilibrium,
normal hemodynamics
Poor skin turgor, dry mucous
membranes, decreased urine
output, concentrated urine,
tachycardia, increased BUN/SCr
ratio
Urine Osm
(mOsm/kg)
> 100
< 100
> 100
> 450
Urine Na
(mEq/L)
< 20
>20
< 20
> 20
< 20
>20
Potential
etiologies
CHF,
Cirrhosis
with
ascites,
Nephrotic
syndrome
Renal
failure
Psychogenic
polydipsia,
Excessive
hypotonic fluid
intake,
Beer potomania
SIADH,a
Cortisol
deficiency,
Hypothyroidism,
Drug-induced
Extra-renal
losses (e.g.,
GI fluid
losses), Third
space losses
Diuretics,
Adrenal
insufficiency,
Cerebral
salt wasting,
Thiazide
diuretics,
Salt wasting
nephropathy
Central nervous system (CNS) disorders – Trauma, stroke, infection, brain tumors
Malignancy – Small cell carcinoma of the lung, pancreatic carcinoma, lymphoma, Hodgkin disease, sarcoma
Pulmonary infection, respiratory failure with positive pressure ventilation
Endocrine disorders – Pituitary tumor, hypothyroidism, adrenal insufficiency
Stress response (surgery, trauma, thermal injury, sepsis, pain)
Drugs
BUN=blood urea nitrogen; CHF = congestive heart failure; EDVI = end-diastolic volume index; GI = gastrointestinal; PCWP = pulmonary capillary wedge pressure;
SIADH = syndrome of inappropriate antidiurestic hormone.
Mechanism
Examples
Increased hypothalamic production
of ADH
Amitriptyline, imipramine
Thioridazine, trifluoperazine
Haloperidol
Carbamazepine, oxcarbazepine, valproic acid
Vincristine, vinblastine, cisplatin, carboplatin, ifosfamide, methotrexate
Nicotine
Bromocriptine
Monamine oxidase inhibitors
Increased sensitivity to or
exogenous administration of ADH
DDAVP, desmopressin
Lamotrigine