CMP Flashcards
What is in a basic metabolic panel
- glucose
- BUN
- creatinine
- BUN/creatinine ratio
- Na
- K
- Cl
- CO2
A comprehensive metabolic panel includes the BMP plus
- total protein
- albumin
- Ca
- alk phos
- ALT
- AST
- total bilirubin
shorthand fishbone diagram
What does the Blood Urea Nitrogen (BUN) lab value signify
- Urea formed in liver -> byproduct of protein metabolism
- deposited in blood and transported to kidney (excretion)
- directly related to liver and kidney function
critical value for BUN
BUN > 100 mg/dl
azotemia
retention of nitrogenous waste
- will see an increase in BUN and creatinine
how can renal disease impact BUN levels
- renal disease -> inadequate urea excretion
- inadequate urea excretion = increased BUN concentration
- *unilateral kidney disease -> compensation
- may not see rise in BUN
how can excess protein intake effect BUN
increase BUN
how can hydration status affect BUN levels
- dehydration = increased BUN
- overhydration = decreased BUN
what BUN levels are expected in combined liver and renal disease
- WNL
- kidneys are not excreting as much but liver is not making as much
How is creatinine formed
- catabolic product on creatine phosphate (used in skeletal muscle contraction)
- daily production and levels related to muscle mass
explain how creatinine levels vary diurnal and postprandial
- Lowest point: 7 am
- Peak point: 7 pm
- eating a high protein meal will cause increase
critical value of creatinine
> 4 mg/dL
creatinine is a marker for which organ’s function
- directly proportional to renal function
- excreted entirely by kidneys
- approximation of GFR
what does elevated creatinine serum concentration mean
- serum concentration tends to rise later -> suggests chronicity of renal disease
serum creatinine levels are influenced by what
- muscle mass and protein intake
- more muscle mass -> elevated creatinine
what is the function of BUN/Cr ratio
- measurement of kidney and liver function
- increased ratio = decrease in the flow of blood to the kidneys
what are some conditions that can cause increased BUN/Cr ratio
- renal hypoperfusion
- GI bleed
- high protein diet
- sepsis/hypermetabolic state
- drugs
what are some conditions that can cause decreased BUN/Cr ratio
- malnutrition
- low protein diet
- ketoacidosis
- drugs
a serum creatinine increase greater than over baseline indicates an acute kidney injury
- > or = 0.5 mg/dL
- >50% over baseline
signs of acute kidney injury
- rapid deterioration of GFR
- decrease in urine output
- accumulation of nitrogenous wastes
- urea and Cr (azotemia)
an elevated BUN/Cr ratio greater than (20:1) is associated with what
- Prerenal Azotemia
- causing reduced renal perfusion
- Azotemia is an elevation of blood urea nitrogen (BUN) and serum creatinine levels.
what are some causes of Prerenal Azotemia
- reduced renal perfusion
- hypovolemia
- shock
- burns
- dehydration
- CHF (low CO)
- MI
- excessive protein ingestion
- sepsis
treatment of Prerenal Azotemia
- restore intravascular volume
- fluids
- reduce or d/c diuretics
- monitor BUN/Cr
an elevated BUN/Cr ratio (10:1) is associated with what
Intrinsic renal azotemia
list some causes of Intrinsic renal azotemia
- acute tubular necrosis: most common cause
- nephrotoxins
- NSAIDS, aminoglycosides
- Glomerulonephritis
Name some causes of Postrenal Azotemia
- BUN/Cr ratio variable
- causes: obstruction to urine flow
- ureter and renal pelvis: blood clot, stones
- bladder
- malignancy
- urethral stricture
function of Chloride
- extracellular anion
- maintains electrical neutrality
- water moves with sodium and chloride
- buffer to assist in acid-base balance
- as CO2+ and H+ rise -> Cl- shifts into cells
critical value of Chloride
- < 80 mEq/L
- > 115 mEq/L
will you often see changes in chloride levels on its own?
- no
- usually part of Na or bicarbonate shifts
- part of anion gap calculation
- (Na+ -(HCO3- + Cl-))
what proteins make up Total protein? Function of total protein
- Total protein = albumin + globulin + prealbumin
- most significant component contributing to osmotic pressure in vascular space
- keeps fluid in vascular space
what is albumin formed? what is its half-life
- formed in liver
- half-life 12-18 days
albumin makes up what percentage of total protein
60%
name some conditions that can decrease albumin levels
- burns
- malnourished
- liver diseae
- third spacing : lost into extravascular space
why is prealbumin measured
-
early indicator of nutritional status
- distinct maker for protein synthesis
- 3 day half life
- synthesis increases within 48 hours of appropriate nutritional support
Acute-phase proteins
class of proteins whose plasma concentrations increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation.
Ex:
- prealbumin: negative
- CRP: positive
Where are globulins formed? Function?
- mostly made in bone marrow and lymph tissue
- building blocks for
- Antibodies
- transport
what are the three groups of globulins
- alpha
- beta
- gamma
- gammaglobulins = immunoglobulins
normal albulin/globulin ratio? What does a lower ratio indicate?
- normally exceeds 1.0
- lesser ratios indicate albumin level affected
function of serum protein electrophoresis
- separates serum components based on electrical charge
- ex: multiple myeloma
- SPEP demonstrates: M-spike (spike in beta or gamma globulin)
What does total calcium measure?
- Total Ca = free (ionized) + protein bound
- measure albumin simultaneously
- absorbed through GI tract (influenced by vit D)
- stored in bone
- excreted by kidney
it is important to monitor total calcium in patients with
- renal failure
- hyperparathyroidism
- malignancies
critical value of total calcium
- < 6.0 mg/dl
- > 13 mg/dl
describe calcium distribution in the body
- 99% bone
- 0.8-1.0% in cells
- 0.1-0.2% in ECF
- 40% is protein bound (albumin)
serum calcium is dependent on what two things
- parathyroid hormone
- secretion -> increase in serum Ca
- vitamin D
serum calcium elevated x 3 is associated with what three conditions
- Hyperparathyroidism
- most common: increased GI absorption, descreased excretion, increased bone reabsorption
- Malignancy: 2nd most common
- tumor metastasis to bone causing Ca reabsorption into blood
- chronic renal failure
- excessive vit D
- granulomatous infections
causes of hypercalcemia: CHIMPANZEES
- Calcium supplementation
- Hyperparathyroidism
- Iatrogenic
- Multiple myeloma, medication
- Parathyroid hyperplasia or adenoma
- Alcohol
- Neoplasm
- Zollinger Ellison syndrome
- Excessive Vit D
- Excessive Vit A
- Sarcoidosis
clinical presentation
- muscle weakness, loss of muscle tone, lethargy, coma
- HTN, EKG abnormalities (short QT interval)
- polyuria, increased thirst, kidney stones
- anorexia, N/V, constipation
hypercalcemia
what are some conditions associated with hypocalcemia
- hypoalbuminemia
-
large blood transfusion
- citrate addictives -> bind free calcium
-
intestinal malabsorption
- vit D deficiency
- renal failure: excessive loss of Ca
- alkalosis: protein binding to Ca
- acute pancreatitis: saponification of fat (fatty acid binds to Ca)
-
hypomagnesemia
- magnesium defiency inhibits PTH
what equation can be used to determine actual total Ca levels when albumin levels are high or low
- = measured total calcium + 0.8 (4.0 - serum albumin)
clinical presentation
- (increased excitability): paresthesia, muscle cramps
- hyperactive reflexes
- positive Chvostek and Trousseau signs
- tetany
- hypotension, EKG changes (prolonged QT interval); arrhythmias
hypocalcemia
CATS go numb”- Convulsions, Arrhythmias, Tetany and numbness/parasthesias in hands, feet, around mouth and lips
what is tetany
- lowered threshold for muscular excitability
- involuntary sustained contractions
- contractions of hands and feet -> carpopedal spasms
Chvostek’s sign
- tapping facial nerve against bone just in front of ear results in contraction of facial muscles
- tetany
Trousseau’s sign
- occluding brachial artery for 3 minutes with BP cuff induces carpal spasms
- tetany
treatment for severe (symptomatic) hypocalcemia
- 100-300 mg elemental calcium
- calcium chloride or D5W
treatment for mild hypocalcemia
- oral calcium + vit D
- calcium carbonate (tums) = no vit D
- calcium citrate = contains Vit D
function of magnesium
- bound to ATP
- organs and neuromuscular tissue depend on Mg
- intimately tied to potassium and calcium to maintain neutral intracellular charge
magnesium is present in what types of food
- green veggies
- grains
- nuts
- meats
- seafood
- *25-65% is absorbed
how is magnesium regulated by the kidneys
- Mg reabsorption decreased if
- serum level of Mg is elevated
- serum level of Ca is elevated
- Mg reabsorption decreased by loop diuretics
Name some conditions that commonly cause increased levels of magnesium
- renal insufficiency
- addison’s disease
- hypothyroidism
- ingestion of Mg-containing compoungs
- antacids, laxatives
clinical presentation
- hyperactive reflexes, paresthesias, muscle weakness and tremors, tetany with + chvostek and + trousseau signs
- prolonged PR and QT intervals
- widening of QRS
Hypomagnesemia
- neuromuscular effects (similar to hypocalcemia)
- **clinically, more common and significant than hypermagnesemia
treatment of hypomagnesemia
- oral replacement
- magnesium oxide (400 mg tabs)
- use cation in patients with renal disease
- IV replacement
- magnesium sulfate infusion followed by additional infusion over 3-7 days
- follow blood levels and DTR’s
how does low Mg+ affect calcium and potassium levels
- hypomagnesemia -> hypocalcemia
- low PTH levels
- impairs ability of kidney to conserve K+
clinical presentation
- hyporeflexia
- muscle weakness; respiratory paralysis
- confusion
- hypotension
- cardiac arrhythmias
hypermagnesemia
phosphate levels are determined by
- calcium metabolism
- Phosphorous is combined with calcium in skeleton
- PTH
- renal excretion
- intestinal absorption (small bowel)
what is the critical value of phosphate (inorganic phosphate is measured)
< 1 mg/dL
what effect does antacids have on phosphate absorption
- dietary phosphate is absorbed in small intestine and decreased with antacids (opposite of Ca)
relationship between phosphate and calcium
- INVERSE
- PTH decreases phosphate reabsorption by the kidneys
what can cause phosphate elevation
- treatment of DKA
- alcohol withdrawal
- hypoparathyroidism
alkaline phosphate has the highest concentrations where in the body
- liver
- in kupffer cells
- biliary tract epithelium
- excreted in bile
- bone
causes of elevated alkaline phosphatase
- extrahepatic and intrahepatic obstructive biliary disease and cirrhosis
- new bone growth : high in adolescents
- osteoblastic metastatic tumors
where is alanine aminotransferase (ALT) found in body?
- predominately in liver
- injury/disease to liver -> release of ALT
AST:ALT ratio < 1 indicates what
- < 1 indicates viral hepatitis
- > 1 indicates hepatocellular disease other than viral hepatitis
- **less accurate if AST exceeds 10 x normal value
AST is released by liver with hepatocellular injury. elevation occurs how long after cell injury
- elevation occurs 8 hrs after injury
- peak: 24-36 hours
AST levels 20 x normal value indicates
acute hepatitis
AST levels 10 x normal indicates
- acute extrahepatic obstruction (i.e. gallstones)
how is biliruben formed
- breakdown of RBC
- hemoglobin released from RBC and broken down into heme and globulin
- heme transformed into biliruben
critical value of total biliruben
- total = unconjugated (indirect) + conjugated (direct)
- critical value= > 12 mg/dL
differentiate between indirect and direct biliruben
- indirect = unconjugated
- normally makes up 70-85% of total bili
- heme -> biliruben
- direct = conjugated
- indirect bili is conjugated in liver
- excreted from liver into hepatic ducts, common bile duct, and bowel
a total serum bili exceeding what value will present with jaundice
2.5 mg/dl
what conditions would lead to elevated levels of unconjugated and conjugated biliruben
- elevated unconjugated
- hepatocellular dysfunction (hepatitis, RBC hemolysis)
- elevated conjugated
- extrahepatic obstruction (gallstones, tumor)
cause of physiologic jaundice of newborn
- newborn liver is immature
- not enough conjugating enzymes
- high circulating blood level of unconjugated bili
- can pass blood-brain barrier -> brain
- encephalopathy (kernicterus)
critical value of unconjugated bili
>15 mg/dL
