ADH Flashcards
Antidiuretic Hormone
Too high: SADH
Too Low: Diabetes Insipidus
SIADH
Symptom of inappropriate Antidiuretic Hormone
-An abnormal production or sustained secretion of ADH
SIADH is characterized by
- Fluid retention
- Serum hypoosmolality and hyponatremia (dilutional)
- Concentrated urine
SIADH Etiology
Malignant Tumors
-small cell carcinoma of lung
Central Nervous System Disorders
-head trauma, stroke, brain tumors
Drug Therapy
-morphine, SSRIs, chemo
Other conditions
-Hypothyroidism, infection
SIADH: Pathogenesis
- Increased ADH
- Increased water reabsorption in renal tubules (w/o Na+)
- Increased intravascular fluid volume
- Dilutional hyponatremia and decreased serum osmolality
SIADH Osmolality
Serum Osmolality: LOW
Urine Osmolality + Specific gravity: HIGH
Serum Sodium: LOW
Urine Output: LOW
Weight: GAIN
**patient is retaining pure water without salt
Clinical Manifestations of SIADH depend on
Severity and rate of onset of hyponatremia
Sx of Hyponatremia
Dyspnea, Fatigue
Neuro: confusion, lethargy, muscle twitching, convulsions, dulled sensorium
GI: impaired taste, anorexia, vomiting, cramps
Severe Symptoms of Hyponatremia occur at
<100-115 mEq/L (135-145)
Possible irreversible neurologic damage
Water intoxication
Sodium levels outside of cell become so low that water enters cell to follow salt, causing cell to burst.
Brain cell swelling is lethal
Pharmacotherapy for SIADH
NOT the first line of treatment.
What is treatment for SIADH?
Directed at the underlying cause (discontinue offending medication)
-Hypertonic saline used sometimes
Chronic SIADH drug
Demeclocycline (Declomycin)
-ex) lung cancer
Demeclocycline: class
Tetracycline broad-spectrum antibiotic
Demeclocycline: USE
Antibiotic therapy
Treatment of SIADH
Demeclocycline: MOA
Interferes w/renal response to ADH
Demeclocycline: AE
Photosensitivity
Teeth staining
Nephrotoxic
Diabetes Insipidus (DI)
A deficiency of ADH or a decreased renal response to ADH
DI is characterized by
Excessive loss of water in urine
2 forms of Diabetes Insipidus
- Neurogenic (Central)
- lesion in brain - Nephrogenic
- kidneys don’t respond
Neurogenic DI Cause (not injuries)
Hypothalamus or pituitary gland damage
Neurogenic DI associated disorders
Stoke
TBI
Brain surgery
Cerebral Infections
Neurogenic DI: Onset
Sudden (following injury)
Is Neurogenic DI permanent?
Usually YES
Nephrogenic DI: Cause
Renal Origin
Loss of kidney function
Often drug-related (lithium)
Associated disorders of Nephrogenic DI
CKD
Onset of nephrogenic DI
Slow
Course: Progressive
DI: pathogenesis
- Decreased ADH
- Decreased water reabsorption in renal tubules
- Decreased intravascular fluid volume
4a. Increased serum osmolality (hypernatremia)
AND
4b. Excessive urine output
Diabetes Insipidus: Osmolality
Serum osmolality: HIGH
Urine Osmolality and specific gravity: LOW
Serum sodium: HIGH
Urine Output; HIGH
Weight: LOSS
DI Symptoms
-Polyuria
-Polydipsia
-Dehydration
-Others based on severity
(electrolyte imbalances)
(hypovolemic shock: Death)
Neurogenic DI Pharmacotherapy
Synthetic ADH replacement
Nephrogenic DI
Thiazide diuretics
-seems strange but has paradoxical effect of decreasing polyuria and increases urine osmolality
(No one knows why)
Desmopressin (DDAVP): MOA
Synthetic ADH replacement therapy
-Antidiuretic effects
Desmopressin (DDAVP): Route
Nasal Spray (Burns), PO, IV, SQ
Desmopressin (DDAVP): AE
Small doses: none
Nasal spray: irritation
Large doses:
- hyponatremia (dilutional from Inc ADH)
- water intoxication (retaining water)
DI Acronym: D-I-L-U-T-E
Dry I&O, Daily weight Low specific gravity Urinates lots Treat: vasopressin (desmopressin) rEhydrate
