L3: CMP and Electrolytes Flashcards
1
Q
Draw the fishbone for CMP.
A
Top row: Na+ | Cl- | BUN
Bottom row: K+ | HCO3- | creatinine
Fish tail: Glucose
2
Q
What are the 2 pancreatic hormones that regulate glucose? When are they released?
A
- Insulin: released in response to high blood glucose
2. Glucagon: released in response to low blood glucose
3
Q
Name 4 functions of the kidney.
A
- Excrete metabolic wastes and substances
- Regulate BP, volume, and electrolyte balances
- Maintain acid-base balance
- Secrete hormones
4
Q
What is BUN? What does it measure?
A
- Urea is a byproduct of liver metabolism and is excreted by the kidneys
- BUN INDIRECTLY measures metabolic function of LIVER and excretory function of KIDNEY
5
Q
How does severe primary liver disease affect BUN?
A
Decreases BUN
Secondarily decreases urea synthesis
6
Q
How does primary renal disease affect BUN?
A
Increases BUN
Secondarily reduces urea excretion
7
Q
Dehydration will cause ____ BUN levels.
A
Increased (causes BUN to become concentrated)
8
Q
Overhydration will cause ____ BUN levels.
A
Decreased (dilutes BUN)
9
Q
Upper GI bleed (UGIB) will cause _____ BUN levels. Why?
A
Increased
Blood overloads gut with protein
10
Q
Low protein diets will cause _____ BUN levels.
A
Decreased
11
Q
High protein diets will cause _____ BUN levels.
A
Increased
12
Q
List 6 causes of hyperglycemia.
A
- Diabetes
- Gestational diabetes
- IV Dextrose infusion
- Drugs (steroids, etc.)
- Stress (trauma, illness, infection, burnes, surgery, etc.)
- Endocrine disorders (Cushing’s, Acromegaly)
13
Q
List 3 causes of hypoglycemia.
A
- Drugs (insulin)
- Starvation
- Endocrine disorders (Addison’s, Hypopituitarism)
14
Q
Name endocrine disorders that would cause hyperglycemia and hypoglycemia (2 each)
A
Hyper: Cushing’s, Acromegaly
Hypo: Addison’s Disease, Hypopituitarism
15
Q
Creatinine is excreted entirely by _____, and therefore is a _____.
A
The kidneys
Measurement of kidney function
16
Q
Creatinine levels are an approximation of ____.
A
GFR
17
Q
Describe the relationship between creatinine and GFR.
A
Inverse relationship
Ex: Doubling of Cr suggests 50% reduction in GFR
18
Q
What are some factors that can cause a misleading creatinine level?
A
Serum levels influenced by:
- Muscle mass
- Protein intake
- Certain drugs
- Unstable, critically ill patients
19
Q
A patient with AKI or chronic kidney disease will show _____ levels of Cr.
A
Increased
20
Q
A debilitated patient will show _____ levels of Cr.
A
Decreased
21
Q
A patient with Myasthenia Gravis or Muscular Dystrophy will show _____ levels of Cr.
A
Decreased
22
Q
A patient with rhabdomyolysis will have _____ levels of Cr.
A
Increased
23
Q
A dehydrated patient will show _____ levels of Cr.
A
Increased
24
Q
What is the BUN/Cr ratio most helpful for determining?
A
Cause of AKI
25
What is a normal BUN/Cr ratio?
~10-20/1 (BUN = 10, Cr = 1)
26
A patient with a prerenal AKI will have a BUN/Cr ratio of:
>20:1
27
A patient with an intrinsic AKI will have a BUN/Cr ratio of:
~10:1
28
A patient with a postrenal AKI will have a BUN/Cr ratio of:
Variable ratio
29
A prerenal AKI is due to an issue with _____. List 3 causes of this disease.
Perfusion
Causes:
- Hypovolemia
- CHF (kidneys not being perfused well due to ineffective pump)
- Change in vascular resistance (stenosis of renal artery)
30
An intrinsic AKI is due to an issue with _____. List 3 causes of this disease.
Filtration
Causes:
- Acute tubular necrosis (IV contrast)*
- Prerenal AKI
- Postrenal AKI
31
A postrenal AKI is due to an issue with _____. List 4 causes of this disease.
Excretion
Causes:
- Ureteral stones
- Bladder outlet obstruction (like bladder cancer)
- BPH
- Urethral stricture
32
Measurement of Cl levels in a CMP is useful for:
eval of electrolyte and acid-base disturbances
33
Hypochloremia and hyperchloremia rarely occur alone. What are these changes usually accompanied by?
Shifts in Na2+ and bicarbonate
34
CO2 levels are an indirect measurement of _____.
Bicarbonate (HCO3)
35
An acid-base disturbance will causes retention or excretion of ____.
Bicarbonate (HCO3)
36
What is the "equation" for total protein?
Total protein = Albumin + Globulin
37
List 6 conditions that fractionated total protein is used to diagnose, evaluate, and monitor.
- Liver disease
- Edematous states
- Protein-losing conditions
- Nutrition status
- Immune disorders
- Cancer
38
Where is albumin synthesized and what does an albumin measurement reflect?
Synthesized in the liver
| Reflects synthetic liver function
39
What is the function of albumin in the body?
- Maintains osmotic pressure (keeps fluid in the vascular space)
- Transports hormones, enzymes, and drugs
40
A dehydrated patient will show _____ albumin levels.
Increased
41
Where is globulin synthesized and what is its function in the body?
Synthesized in bone marrow and lymph tissue
| Globulin is building block for antibodies, acute-phase reactants, and transport
42
When albumin levels are low, what typically happens to globulin levels and why?
Globulin levels will be elevated to maintain normal total protein levels
43
List 6 causes of hypoalbuminemia.
- Liver disease
- Protein-losing enteropathies (Crohn's or celiac disease)
- Protein-losing nephropathies (nephrotic syndrome)
- Burns
- Malnutrition/malabsorption
- Inflammatory diseases
44
Why can a patient with an inflammatory disease present with low albumin levels?
Inflammatory disease causes globulins to increase so albumin levels decrease
45
A patient presents with normal total protein with low albumin and normal/increased globulin. Name 2 possible conditions that would cause this.
- Chronic liver disease
| - Collagen vascular disease (Lupus)
46
A patient presents with an increased total protein with increased globulin fraction. Name a condition that might cause this.
Multiple Myeloma (remember M-spike and Bence-Jones proteins in urine)
47
What labs would you expect to see (in regards to fractionation of total protein) in a patient with chronic liver disease?
Normal total protein with low albumin and normal/increased globulin
48
What labs would you expect to see (in regards to fractionation of total protein) in a patient with multiple myeloma?
Increased total protein with increased globulin fraction
49
Name the 4 liver tests in a CMP. Which 2 are transaminases?
AST *transaminase
ALT *transaminase
ALP
BILI
50
What do the liver test detect?
Injury/disease of the hepatobiliary system
51
Which 2 liver tests will be affected when there is injury to the hepatocytes? (Hepatocellular pattern)
AST and ALT
52
Which 2 liver tests will be affected when there is injury to the bile ducts and/or bile flow?
ALP and total Bili
53
Aspartate Aminotransferase (AST) is an enzyme found where? What happens to AST levels when there is injury/disease affecting these tissues?
Found in liver, cardiac muscle, skeletal muscle, kidney, and brain
Injury/disease = Increased AST into bloodstream
54
Alanine Aminotransferase (ALT) is an enzyme found predominantly where? What happens to ALT levels when there is injury/disease affecting this tissue?
Liver (found in lesser quantities in kidneys, cardiac muscle, skeletal muscle
Injury/disease = Increased ALT into bloodstream
55
Alkaline Phosphatase (ALP) is an enzyme found predominantly where? What is it excreted into?
Liver, biliary tract, and bone
Excreted into bile
56
What happens to ALP levels when there is an obstruction of bile flow?
ALP increases
57
What is the "equation" for total bilirubin (Bili)?
Total Bili = Unconjugated (indirect) + Conjugated (direct)
58
What are the 4 steps of bilirubin traveling from the spleen to your poop (idk what this process is called lmao). Indicate if it is conjugated or unconjugated at each step.
1. Hemolysis (unconjugated)
2. Uptake (unconjugated bound to albumin)
3. Conjugation (conjugated)
4. Excretion (conjugated from biliary ducts into duodenum)
59
Jaundice is caused by:
Abnormally high levels of bilirubin (can be caused by defect at any stage)
60
Generally, AST and ALT > ALP reflects what kind of process?
Hepatocellular
***Serum bili may also be elevated!
(see slide 42 for DDx of elevated AST and ALT - too many)
61
Generally, AST and ALT < ALP reflects what kind of process?
Cholestatic
***Serum bili may also be elevated!
(see slide 43 for DDx of elevated ALP)
62
A patient presents with an isolated elevated ALP (all other tests normal). What should this raise suspicion for? What is the most common cause?
Raises suspicion for extrahepatic cause
| -BONE is the most frequent extrahepatic source of ALP!
63
What test can we use to distinguish between liver and bone isolated ALP levels?
ALP isoenzymes
64
What are 3 causes of hyperbilirubinemia from UNCONJUGATED bilirubin?
- Hemolysis
- HF (impaired hepatic bilirubin uptake)
- Gilbert syndrome (impaired bilirubin conjugation)
65
What are 4 causes of hyperbilirubinemia from CONJUGATED bilirubin?
- Hepatitis
- Drugs/toxins
- Liver infiltration (TB)
- Biliary obstruction
66
What roles does Ca2+ play in the body?
- Neurotransmission
- Cardiac function
- Muscle contraction
- Blood clotting
67
There is an inverse relationship between calcium and _____.
Phosphorus
68
What percentage of calcium exists in bone?
99%
69
What is the distribution of ECF calcium?
Ionized (FREE): 50%
Complexed: 10%
Protein-bound (albumin): 40%
70
Which form of calcium is physiologically active and unaffected by serum albumin levels?
Ionized calcium
71
Which liver test is most specific to the liver?
ALT (more specific than AST)
72
What form of calcium is the most accurate measurement of serum calcium?
Ionized calcium
73
In regards to protein-bound Ca2+, when serum albumin is low then:
calcium level will also be low
| albumin and calcium should be measured simultaneously
74
What is complex calcium often chelated with?
Citrate (prevents clotting)
75
What is the equation for corrected Ca?
Corrected Ca = Total serum Ca + 0.8 x (4.0 - serum albumin)
76
What 5 things influence renal physiology?
- PTH
- Calcitonin
- Vitamin D
- GI
- Kidneys
77
State what happens to the parathyroid gland, bones, gut, and kidney when Ca2+ levels are low.
PTgland: Releases PTH which causes:
Bones: release Ca2+
Kidneys: Increase Ca2+ uptake and activate Vit D
Gut: Vit D + PTH cause increased Ca2+ uptake
78
State what happens to the thyroid gland, bones, gut, and kidney when Ca2+ levels are high.
Thyroid gland: Releases calcitonin which causes:
Bones: Ca2+ deposition
Kidneys: reduced Ca2+ uptake
Gut: reduced Ca2+ uptake in intestines
79
What are the 2 primary causes of hypercalcemia? (90% of cases)
Hyperparathyroidism (most common) and malignancy
80
Why does hyperparathyroidism cause hypercalcemia?
Bone resorption (Ca released from bone into blood)
81
Describe what happens neurologically/MSK with hypercalcemia.
DECREASED neuromuscular excitability:
- Muscle weakness
- Loss of muscle tone
- Lethargy
- Stupor
- Coma
82
Describe the cardiovascular effects of hypercalcemia.
-EKG abnormalities (SHORTENING OF QT INTERVAL)
83
Describe the renal effects of hypercalcemia.
- Polyuria,
- Polydipsia
- NEPHROLITHIASIS (kidney stones made of Ca)
84
Describe the GI effects of hypercalcemia.
- Anorexia
- N/V
- CONSTIPATION
85
What is the most common cause of hypocalcemia?
Hypoalbuminemia
86
List 5 other causes of hypocalcemia (aside from hypoalbuminemia)
- Hypomagnesemia (Mg def. inhibits PTH and Ca is not mobilized)
- Hypoparathyroidism
- Parathyroidectomy
- Renal failure
- Intestinal malabsorption/Vit D def.
87
What is a positive Chvostek's sign and Trousseau's sign indicative of?
Hypocalcemia
88
Describe what happens neurologically/MSK with hypocalcemia.
INCREASED neuromuscular excitability (tetany)
- Paresthesias (peri-oral, extremities)
- Hyperactive reflexes; caropedal spasms
- Chvostek's sign
- Trousseau's sign
89
Describe the cardiovascular effects of hypocalcemia.
- PROLONGED QT interval
| - Arrhythmia
90
What are some symptoms of tetany (related to hypocalcemia)?
- Paresthesias: Numbness and tingling of lips, fingers, or toes
- Contractions of hands and feet (carpopedal spasms)
91
What is Chvostek's sign?
- Tapping facial nerve against the bone just anterior to the ear
- Positive sign: contraction of facial muscles
92
What is Trousseau's sign?
- Occluding brachial artery for 3 minutes with BP cuff
| - Positive sign: Induced carpal spasms
93
What is the management for hypocalcemia?
Mild: Oral Ca +/- Vit. D. supplementation
Severe/Sx: IV Ca gluconate
-Correct hypomagnesia if low
94
Where is dietary phosphorus absorbed? What is the most important regulator of serum phosphate levels?
Absorbed in small intestine
| Regulated by kidney
95
There is an inverse relationship between phosphorus and _____.
Calcium
96
List 4 causes of hyperphosphatemia.
- Renal failure
- Hypoparathyroidism
- Hypocalcemia
- Exogenous phosphorus
97
List 5 causes of hypophosphatemia.
- Malnutrition/malabsorption
- Hyperparathyroidism
- Chronic alcoholism
- Severe vomiting/diarrhea
- Cellular shift (electrolytes driven into cells too quickly; seen with insulin and refeeding syndrome)
98
What is the clinical presentation of hypophosphatemia?
Severe levels = <1.0 mg/dL
- Muscle weakness
- Rhabdomyolysis
- Seizures
99
What is the management for hyperphsphatemia?
- Treat underlying cause
- Exogenous phosphorus restrictions
- Dietary phosphate binders
- Dialysis
100
What is the management for hypophosphatemia?
- Treat underlying cause
| - Phosphate repletion regimens as appropriate
101
Mg is intimately tied to:
Ca and K
102
How does hypomagnesemia lead to hypocalcemia?
Inhibits PTH activity
103
How does hypomagnesemia lead to hypokalemia?
Impairs ability of kidney to conserve K
104
List 2 causes of hypermagnesemia.
- Renal insufficiency (not properly excreted)
| - Large Mg load (ingestion of Mg containing meds)
105
List 4 causes of hypomagnesemia.
- Malnutrition/malabsorption
- Severe diarrhea
- Alcoholism
- Cellular shift
106
What are the symptoms of hypermagnesemia?
Decreased DTRs, bradycardia, hypotension
107
What are the symptoms hypomagnesemia?
Neuromuscular excitability (tetany), cardiac arrhythmias (torsades de pointes)
108
How do you manage hypermagnesemia?
- Cessation of magnesium-containing meds
- Isotonic fluids + loop diuretics
- Dialysis
- IV calcium
109
How do you manage hypomagnesemia?
- Asymptomatic: oral Mg
- Symptomatic: IV Mg
* Correct Ca and K deficiences as well
