Renal Labs Part 2 Flashcards
What is the primary circulating cation? (extracellular cation)
Na
What is the normal range for sodium?
136-145 mEq/L
How does sodium indicate free body water?
When free water is increased, Na is diluted and Na levels decrease.
When free water is decreased, Na is concentrated and levels increase.
What ion is a major contributor to plasma osmolality?
Na
What is a normal serum osmolality?
280-295mOsm/kg H2O
What hormone regulates body water and osmolality?
Antidiuretic hormone
What stimulates ADH?
Increased osmolality
Hypovolemia
Thirst
By what mechanism does ADH cause the body to hold onto water?
Increases the permeability in the collecting tubule allowing more water to be reabsorbed
Name a few conditions that would cause increased serum osmolality.
Hypernatremia Hyperglycemia Ketosis Dehydration Diabetes insipidus
Name 2 conditions that would cause decreased serum osmolality.
Overhydration
SIADH
Common cause of SIADH?
Iatrogenic causes
Diabetes insipidus is caused by?
Inadequate amount of ADH present
Symptoms of diabetes insipidus
Increased thirst, polyuria, dilute urine
What test evaluates the ability of the kidney to concentrate urine?
Urine osmolality
Name 2 conditions that would increase urine osmolality?
SIADH
CHF
Name 2 causes of decreased urine osmolality?
Diabetes insipidus
Excess fluid intake
What is more worrisome, hyponatremia or hypernatremia?
Hyponatremia
Serum sodium below ____ is hyponatremia?
136
What are the two types of hyponatremia?
Sodium depletion
Dilutional
Symptoms of hyponatremia typically are not seen until serum sodium below ____
120
Symptoms of hyponatremia?
lethargy, nausea, muscle cramps, and the bad one: cerebral edema
Serum sodium above ____ is hypernatremia.
145
Causes of hypernatremia?
Impaired thirst (dementia, stroke), water loss without sodium loss (burns), and dehydration
Treatment for hypernatremia?
Rehydration
What test distinguishes between renal and nonrenal causes of hyponatremia?
Urine sodium
What are the three categories of hyponatremia?
Isotonic hyponatremia
Hypotonic hyponatremia
Hypertonic hyponatremia
Causes of isotonic hyponatremia?
Hyperproteinemia
Hyperlipidemia
Causes of hypertonic hyponatremia?
Hyperglycemia
Contrast agents
Hypotonic hyponatremia is further categorized into what 3 categories?
Hypovolemic hypotonic hyponatremia
Euvolemic hypotonic hyponatremia
Hypervolemic hypotonic hyponatremia
Causes of hypervolemic hypotonic hyponatremia?
Edema
CHF
Advanced renal failure
liver disease
Causes of euvolemic hypotonic hyponatremia?
SAIDH
Postop hyponatremia
Hypovolemic hypotonic hyponatremia can be caused by?
Dehydration, nausea, vomiting (U Na < 10)
Renal salt loss (U Na >20)
What is the primary intracellular cation?
Potassium (K)
Normal range for K?
3.5-5.5
Potassium plays an important role in_____ function
Cardiac muscle
Symptoms of hypokalemia?
Malaise, skeletal muscle weakness, arrythmias
EKG findings in hypokalemia?
Flattened or inverted T waves
Causes of hypokalemia?
Diuretic usage Burns Glucose administration Licorice ingestion Aldosterone excess (enhances K excretion)
Causes of hyperkalemia?
Renal failure
Acidosis
ACEIs
Hemolysis
Symptoms of hyperkalemia?
Arrhythmias, cardiac arrest, numbness, tingling, weakness
EKG findings in hyperkalemia?
Peaked T waves
Most abundant extracellular ion?
Chloride
Normal range of chloride?
96-106
Conditions that would increase chloride levels?
Dehydration
Metabolic acidosis
Conditions that would decrease chloride levels?
Overhydration
SIADH
Vomiting
What is the primary buffer system of the body?
Carbonic acid/bicarbonate system
Carbonic acid is regulated by?
The lungs
Bicarbonate is regulated by?
The kidneys
