BMP highlights Flashcards
2) List the tests in a BMP (know these)
3) What is the test that’s freq. included?
1) Sodium, potassium, chloride, bicarb(onate), BUN, creatinine, glucose
2) Calcium
Doubling of serum creatinine suggests ___% reduction in GFR
50%
Urea formed in the liver as a metabolic byproduct; BUN is excreted by the kidneys
Normal range of HCO3: _________ mEq/L
(know this)
22-26
Urine concentration of an electrolyte is helpful when compared to serum levels
Gold-standard – 24-hour urine collection to monitor electrolyte excretion
Fractional excretion (FE) of an electrolyte is more convenient
Low fractional excretion indicates ________
High fractional excretion indicates ________
Osmolality of all solutes (electrolytes and others) in plasma is 280-295 mmol/kg
slide 12 chart
slide 12 chart
Sodium:
1) The main __________ cation
Main determinant of extracellular __________ (affects fluid shifts)
1) extracellular
2) osmolality
_____________ is the most common electrolyte abnormality
Hyponatremia
sodium chart slide 16
slide 20
slide 21
Clinical manifestations and treatment depend on how far Na+ is outside of the normal range (severity) and the acuity of onset*
Hypo/hypernatremia: Differentiate between acute and chronic
Acute <48 hrs vs. chronic ≥48 hrs
*Same concept applies to electrolyte disorders in general
Hypernatremia
Acute and severe symptoms with Na+ >160:
What are the initial labs for hyponatremia?
Initial labs should include:
Serum and urine electrolytes
Serum and urine osmolality
What are the initial labs for hypernatremia?
Serum sodium
Urine volume flow rate (oliguric or nonoliguric)
Urine osmolality
Hyponatremia: Serum osmolality low most of the time
Urine osmolality usually high
What are the categories of hyponatremia? List causes of each
slide 25
Pseudohyponatremia (normal serum osmolality
Severe hypertriglyceridemia or hypergammaglobulinemia throws off sodium reading
Increase sodium by _____ for every 100mg/dL rise in plasma glucose above normal (100 mg/dL)
1.6
What is the most common hyponatremia? How can you break that down further?
Hypotonic (hypo-osmolar) hyponatremia
slide 27
urine osm <100, dilute urine)*
List Hyponatremia: Etiologies (con.)Hypotonic – ADH Independent
Primary (Psychogenic) polydipsia
“Beer potomania”
“Tea and toast diet”
Renal impairment
Patients with advanced renal impairment from AKI or CKD (GFR <_____) can cause hyponatremia
15
slide 28
_________________ causes are the most common category of hypotonic hyponatremias (urine osm >100, concentrated urine)
ADH dependent
ADH Dependent causes involve what?
This is the appropriate response to what?
failure to suppress ADH
hypovolemia or reduced effective arterial volume
Categorized by pt volume status
Hyponatremia: Etiologies (con.)Hypotonic – ADH Dependent - Hypervolemic
Usually occurs in the setting of edematous states (cirrhosis, heart failure, rarely nephrotic syndrome)
Because of RAAS activation and increased aldosterone, urine sodium is low
Hyponatremia: Etiologies (con.)Hypotonic – ADH Dependent - Hypervolemic
Give 3 examplesof causes
SIADH is a cause of what?
32
slides 32 + 33 3 causes
34 bold
Hyponatremia: What two things should the lab consider? Why?
1) Serum and urine electrolytes (specifically Na+)
2) Serum and urine osmolality
-Urine osmolality is used as a surrogate for ADH activity
Factors affecting serum K+ concentration include what?
1) Aldosterone
2) Sodium reabsorption
3) Acid-base balance
Hypokalemia:
1) Mild/mod clinical features?
2) Severe?
1) Mild/moderate: K+ 3.0-3.4
usually asymptomatic
2) Severe: K+ <2.5-3.0
Muscle weakness (including constipation from effects on GI smooth muscle), arrhythmias
Hypokalemia
Features of underlying cause
E.g. nephrogenic DI affects concentrating ability of urine: polyuria and polydipsia
Hypokalemia: Etiologies
Assessing urine potassium can help distinguish _________ from ___________ causes of hypokalemia
renal from non-renal
47
47
Evaluate for acid-base disorders
49
Hyperkalemia: Etiologies
Increased K+ intake=
Increased net K+ release from cells
Reduced urinary K+ excretion
Medications
) Increased net K+ release from cells
slide 51
slide 51
Impaired renal elimination of K+
52 bold
53 bold chart
58
Usually measuring total serum calcium is sufficient because changes in total mirror those in ionized fraction
Exceptions (total calcium is low but ionized may be normal) include: hypoalbuminemia, certain acid-base disorders
When serum albumin is <4 g/dL, serum Ca2+ is reduced by ~0.8 mg/dL* for every 1 g/dL of albumin below normal (4)
If albumin is low, total calcium is expected to be low measure both when evaluating calcium
(Albumin is part of the CMP)
58
Usually measuring total serum calcium is sufficient because changes in total mirror those in ionized fraction
Exceptions (total calcium is low but ionized may be normal) include: hypoalbuminemia, certain acid-base disorders
When serum albumin is <4 g/dL, serum Ca2+ is reduced by ~0.8 mg/dL* for every 1 g/dL of albumin below normal (4)
If albumin is low, total calcium is expected to be low measure both when evaluating calcium
(Albumin is part of the CMP)
Calcium Homeostasis Depends on _________ and ___________ (1,25-dihydroxyvitamin D), as well as negative feedback loops triggered by calcium
PTH and calcitriol
Calcium & Phosphorus are usually __________ related in the body
inversely
What is the hallmark of hypocalcemia?
important
Tetany
Chvostek sign, Trousseau sign
Hypocalcemia
Hypocalcemia: Etiologies
Bold list slide 63
other bold slide 63
starred
Confirm it is true hypocalcemia: e.g., low total serum calcium and low ionized calcium
Most helpful lab to determine etiology is PTH
Serum phosphate usually high in hypoparathyroidism or advanced CKD and low in vitamin D deficiency
Serum magnesium often low; may also measure vitamin D levels, renal function (creatinine)
starred chart 64
starred chart 64
starred chart 64
Hypercalcemia: Clinical Manifestations
May affect GI, kidney, and neurologic function
66
1) Asymptomatic, mild hypercalcemia: usually primary hyperparathyroidism
2 )Symptomatic, severe hypercalcemia: usually malignancy-associated hypercalcemia
67
Elevated serum total and ionized calcium
May have hypophosphatemia
Serum PTH levels: used to determine if hypercalcemia is PTH-mediated or not
High: primary hyperparathyroidism is the most likely cause
Low: eval for non-PTH-mediated cause (malignancy, Vit. D intoxication, etc.)
Both hypo- and hypermagnesemia can decrease PTH secretion/action and provoke ___________
hypocalcemia
69
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69
69
69
70 vitamin D deficiency, hyperparathyroidism
Hypophosphatemia:
70
