BMP Flashcards
When do you order a BMP?
- Hospital Admission
- Fluid Status in Doubt
- Pt on a medication that effects electrolytes (i.e. diuretics)
Components of the BMP
- Na+
- K+
- Cl-
- HCO3-
- BUN
- Cr
- Ca2+
- Glucose
This is the most common electrolyte disorder counting for 5% of hospitalized elderly patients.
Hyponatremia
Common Cause of Hyponatremia
Excess Fluid Build Up
Symptoms of Hyponatremia
- Headache
- Lethargy
- Confusion
- Seizure
Depends on the rapidity of onset
Classification of Hyponatremia
- Calculate Serum Osmolality
- Measure Urine Osmolality to eliminate pyschogenic polydipsia
- Assessment of ECF Volume
How do you calculate serum osmolality?
Osmolality = 2(Na+) + (Glucose/18) + (BUN/2.8)
Normal Range of Serum Osmolality of Sodium
285-295
What is the most common type of Hyponatremia?
Low Osmolality Hyponatremia
What are the causes of hyponatremia with high extracellular volume?
- Heart Failure
- Renal Failure
- Liver Failure/Cirrhosis
What are the causes of hyponatremia with normal extracellular volume?
- SIADH
- Hypothyroidism
- Adrenal Insufficiency
What are the causes of hyponatremia with low extracellular volume?
- Vomiting
- Renal Sodium Wasting (Intrinsic vs. Extrinsic/Diuretics)
Goals of Therapy for Hyponatremic Patient
- Restrict H2O intake or Promote H2O loss
- Replace Sodium if needed (rare)
- Correct the underlying cause
How is Hyponatremia Treated?
Passively
- For heart, kidney, liver failure, the hyponatremia is usually mild and fluid restriction of approx. 1200 cc of fluid per day is all that is needed.
- Diuretics can be used with caution for faster response or if fluid restriction can’t be adhered to.
How is Severe Hyponatremia Treated?
Actively
- Coma: Sz related to Hyponatremia
- Can give Saline to Correct
- Need to remember not to correct too quickly
- Rate of correction should be 0.5 mmol per hour (no more than 12 mmol in a day)
What is the condition precipitated by correcting hyponatremia too quickly?
Central Pontine Myelinolysis
*Manifests by confusion, paralysis, CN deficits (Locked-In Syndrome)
Condition where there is excess Anti-Diuretic Hormone causing Hyponatremia
SIADH
Syndrome of Inappropriate Anti-Diuretic Hormone Release
Function of ADH
Promotes Water Retention in the Renal Tubules
Hyponatremia is defined by what level of Sodium?
< 135
Hypernatremia is defined by what level of Sodium?
> 145
Cause of Hypernatremia
- Not enough water in
OR - Too much water out
*Extremely rare to raise sodium by giving too much sodium
Causes of “Not Enough Water In” Based Hypernatremia
Impaired Thirst
- Can be caused by Tumor or Stroke in Hypothalamus (Osmolality Center)
- No access to water (Common)
Causes of “Too Much Water Out” Based Hypernatremia
- Dehydration from Heat, Burns, Diarrhea
- Renal Water Loss from Diabetes Insipidus
- Essentially the opposite of SIADH
- Water not absorbed in distal tubule and is wasted in excess sodium
Symptoms of Hypernatremia
- Thirst
- Hypotension
- Muscle Weakness, Irritability
- Confusion
- Coma, Sz
Total Body Water Per Body Weight in Men?
In Women?
60% of Weight Men
50% of Weight Women
What is the treatment of Hypernatremia?
Calculate a Water Deficit and Replace over 24 Hours
How do you Calculate Water Deficit in Men?
WD = [(Plasma Na+ - 140) x TBW] / 140
This is primarily an intracellular cation and can increase when there is lysis of the cells.
Potassium